chemistry fundamentals Flashcards
(485 cards)
1
Q
What unit of volume is used for laboratory work? Why?
A
Litres, because, the cubic meter, the SI unit for volume is too large for most lab work
2
Q
1 L = ? cubic meter
A
1000
3
Q
Define Molarity
A
Moles of solute per litre of solution
4
Q
1mL = 1 cm3, True or False?
A
True
5
Q
Litre is used to express the volume of solids? T/F
A
False, litre is used to express the volumes of liquid and gases
6
Q
Define Angstrom?
A
Angstrom is a unit of length equals to 10^-10m. The atomic radii and bond lengths are typically around 1 to 3 A
7
Q
Define Density? What are its SI units?
A
It is mass per volume. m/V. The SI Units of Density is kilogram per cubic meter (kg/m^3)
8
Q
What is density most often expressed in?
A
Grams per cubic centimeter
9
Q
What is the density of water?
A
1 g/cm3
10
Q
Define Molecule
A
When two or more atoms form a covalent bond they create a molecule
11
Q
How do we know the identity of a compound and the number of its atoms?
A
Using the molecular formula
12
Q
Are molecular formula and empirical formula the same thing?
A
No, to get the empirical formula divide all subscripts by a common factor. Empirical formula is a reduced form of the molecular formula
13
Q
What is the formula for ammonium?
A
NH 4 +
14
Q
Identify H3O+
A
Hydronium
15
Q
Formula for acetate?
A
CH3CO2-
16
Q
IDENTIFY HCO3-
A
bicarbonate
17
Q
FORMULA FOR CYANIDE
A
CN-
18
Q
IDENTIFY OH-
A
HYDROXIDE
19
Q
FORMULA FOR NITRATE
A
NO 3 -
20
Q
FORMULA FOR NITRIDE
A
NO2-
21
Q
IDENTIFY CL04-
A
PERCHLORATE
22
Q
FORMULA FOR CARBONATE
A
CO3 2-
23
Q
IDENTIFY SO4 2-
A
SULFATE
24
Q
IDENTIFY SO4 2-
A
SULFATE
25
IDENTIFY SO3 2-
SULFITE
26
FORMULA FOR PHOSPHATE
PO 4 2-
27
Define formula weight? What is the unit?
Sum of all the atomic weights of all the atom in the molecule. The unit is atomic mass unit (amu). It says weight but it really is mass
28
Define one amu?
is equal to exactly 1/12 the mass of an atom of carbon -12
29
What is mole?
it is a particular number of things. One mole contains 6.02 x 10 ^23 entities (Avogadro's number)
30
What is Avogadro's number denoted by?
N A in the subscript or N 0 in the subscript
31
What is the link between atomic mass unit and grams?
Avogadro's number
32
What is the formula to calculate number of moles?
mass in grams/ molecular weight
33
What formula is preferred to calculate percent mass composition?
Empirical formula
34
What expresses the concentration of a solution in terms of moles of solute per volume?
Molarity
35
[ ] = concentration? T/F
True
36
What is Mole fraction?
Fraction of moles of a given substance relative to the total moles in the solution
37
When is it more useful to use mole fraction over molarity?
Mole fraction is used when more than one solute is present in a solution and is often used in gases
38
What is the Law of conservation of mass?
the amount of mass does not change in a chemical reaction
39
Define stoichiometry co-efficients?
they tell us in what proportions the reactants react and products are formed
40
The stoichiometric co-efficients are used to give the ratios by mass. T/F
False, they give ratios of the number of molecules or moles
41
What is a limiting reagent?
Whatever reactant runs out first to limit the production of a product is called limiting reagent
42
Is limiting reagent a reactant that is present in the smallest amount? T/F
No, Limiting reagent is the reactant that is consumed first and not necessarily the reactant that's initially present in the smallest amount.
43
A product can be a limiting reagent? T/F
False, only the reactants are limiting reagent.
44
What are the four states used in chemical formula?
Solid, liquid, gas and aqueous
45
Define catalyst.
A substance that increases the rate of reaction without being consumed
46
What does the oxidation state of an atom indicate?
Atom's oxidation state or number indicates how the atom's ownership of its valence electrons changes when it forms a compound.
47
What results in a positive vs negative oxidation state?
Giving up the ownership of valence electrons results in positive oxidation and accepting ownership of valence electrons results in a negative oxidation state.
48
What is the oxidation state of any element in its standard state?
0
49
What is the rule for oxidation state of an atom in a molecule/ion?
The sum of the oxidation state of the atoms in a neutral molecule must always be 0. For ions, the sum of the oxidation states of the atoms must always equal to the ion's charge
50
What is the oxidation state of Group 1 and Group 2 metals?
+1 for Group 1 and +2 for group 2
51
Oxidative state of Flourine?
-1
52
What are the rules for oxidation state of hydrogen
+1 when bonded to something that is more electronegative than carbon, -1 when bonded to something less electronegative than carbon and 0 when it is bonded to carbon
53
What is the oxidative state of oxygen and atoms that belong to the oxygen family?
-2
54
What oxidative state do halogens have?
-1
55
When does O2 not have a oxidative state of -2?
In peroxides, oxygen is in a -1 oxidative state.
56
What is the pneumonic for the order of electronegativity?
FONClBrISCH (Fawn-cull-brish), most to least
57
In FONClBrISCH, identify the oxidative states of H.
Anything before C is +1 for H, anything that is not here is -1 for H.
58
A metal will never assume a negative oxidation state? T/F
True
59
What is an atom? What are some parts of the atom?
The smallest unit of any element is called an atom. All atoms contain a nucleus and outside the nucleus, there are electrons.
60
What is inside a nucleus?
Protons and nuetrons
61
What are nucleons?
Protons and neutrons are collectively known as nucleons
62
Charge of protons
+1
63
Charge of nucleus
0
64
charge of electrons
-1
65
How are electrons held inside an atom?
Through the electrostatic attraction of positively charged nucleus
66
every neutral atom has equal charge of electrons outside the atom and protons inside the atom? T/F
True
67
What is atomic number (Z)?
The number of protons in a nucleus of an atom
68
Are protons represented by a subscript or a superscript?
Subscript
69
What is the mass of protons and neutrons?
1.66 x 10 ^-27
70
What is the mass of an electron?
0.05 % mass of the protons or the neutrons
71
What contributes to all the mass of an atom
Nucleus
72
How do you find the mass number of an atom? (A)
# of protons + # of neutrons
73
What are isotopes?
Two atoms of same element differ in their number of neutrons. (Protons stay the same)
74
What is an atomic weight of an element?
weighted average of all the masses of its naturally occurring isotopes
75
Define ions, anions, cations?
When a neutral atom gains or loses electrons, it becomes charged and the resulting atom is called an ion. A negatively charged atom is called anions. A positively charged atom is called cation.
76
Charge of an atom when it gains an electron
-1
77
Charge of an atom when it loses an electron
+1
78
How are neutrons and protons held together?
by strong nuclear force
79
Electrical force is stronger than nuclear force? T/F
False, nuclear force is stronger than electrical force between charged particles.
80
What is the limitation of the nuclear force?
It only works over extremely short distances
81
What is a radioactive nuclie?
An unstable nuclie
82
Define radioactive decay?
unstable nuclei undergo a transformation to make them more stable, altering the number and ratio of protons and neutrons or lowering their energy,
83
Difference between a parent nucleus versus the daughter?
The nucleus that undergoes the radioactive decay is known as the parent and the resulting more stable nucleus is known as the daughter
84
3 types of radioactive decay?
Alpha, Beta and gamma
85
Define alpha decay
When a large nucleus wants to become more stable by reducing the number of proton and neutrons by emitting an alpha particle.
86
What is the symbol for an alpha particle and what does it consist of?
α (4 superscript and 2 subscript). It consists of 2 protons and 2 neutrons
87
What atom is the alpha particle similar to?
Helium
88
Alpha decay reduces the parent's atomic number by ---- and mass number by ----
2 and 4
89
What particles cant travel very far and can be stopped by human skin and piece of paper?
Alpha Particles
90
What is beta decay?
Beta decay involved conversion of neutrons into protons or vice versa through the action of the weak nuclear force.
91
3 types of beta decay?
β− decay, β+ decay and electron capture
92
What type of particles can be stopped by aluminium foil and a centimetre of glass and plastic
Beta particles
93
Explain β− decay
β− decay is when an unstable nucleus contains too many neutrons, it may convert those into a proton and an electron which is ejected. As a result the atomic number of the daughter nucleus is 1 greater than the parent and the mass stays the same. (coverts into proton and electron, -ve and +ve = neutral,)
94
Explain β+ decay.
When an unstable nucleus contains too few neutrons, it converts a proton into a neutron and a positron is ejected. The atomic number of the daughter nucleus is one less than the parent nucleus but the mass stays the same. (protons gets converted into neutron that is neural, the leftover positive charge is emitted in a form of a positron)
95
Difference between an electron and positron?
Positron is antiparticle of electron. It is identical to an electron but has a positive charge.
96
What is the most common type of Beta decay?
β- decay.
97
Explain electron capture
An unstable nucleus increases its number of neutrons by capturing an electron from the closest shell (n=1) which is then used in the conversion of protons into neutrons ( -ve charge from electrons and +ve from protons = neutral neurones). The atomic number is reduced by 1 and mass stays the same.
98
Explain gamma decay
After the nucleus has undergone alpha or beta decay, it is in an excited state of energy. It can relax to its ground state by emitting energy in the form of one or more photons of electromagnetic radiation. This radiation changes neither the atomic number nor the mass number
99
What are the characteristics of gamma photons?
They have very high frequency and energy . They do not have mass or charge so they can penetrate most matter effectively.
100
Order in terms of least to highest degree of penetration, beta, alpha and gamma
Alpha < beta < gamma
101
True or False, alpha, beta and gamma decay change the identity of the nucleus
False, gamma doesn't change the identity. Gamma decay is simply the expulsion of energy
102
Define half-life
Time it takes for one-half of some sample of the substance of decay.
103
True or False. Shorter the half life, the faster the decay?
True
104
What is nuclear binding energy?
The energy that was released when individual protons and nucleus were bound together by strong force to form a nucleus. This is the same energy that would require to break a nucleus into nucleons.
105
What is the relationship between the binding energy and stability?
direct
106
Explain mass defect?
When nucleons bind together to form a nucleus, some mass is converted into energy, so the mass of the nucleus when you combine all the nucleons is less than the sum of individual nucleon masses. The difference is called mass defect
107
Mass defect and nuclear binding energy are different, True or false
True, but they are equivalent through Einstein's equation for mass energy equivalence E = mc 2
108
What is the characteristic of a mass defect of a stable nucleus
It is always positive
109
How would you convert kg to joules?
Multiply by 9 x 10 ^16
110
Formula for nuclear binding energy?
E = mc2
111
In a nuclear domain, energy is expressed in volts?
Electronvolts, 1 ev = 1.6 10 ^ -29
112
What is c?
Speed of light (3.0 x 10^8)
113
Formula for nuclear binding energy in MeV?
m in amu x 931.5 ev, 1 emu = 1.66 x 10 ^ -27
114
What does emission spectrum display?
different wavelengths and energies of light for the gas passing through it
115
Formula for energy of a photon?
E = hf, h is planck's constant (6.63 x 10^-34)
116
Frequency in terms of speed of light and wavelength formula?
F = c/wavelength
117
Explain Bohr's model of atom?
1. electrons in an atom orbited the nucleus like planets did the sun
2. distance from the nucleus is related to the energy of the electrons, electrons with large energy orbited at greater distances.
3. electrons in the atom cannot assume any arbitrary energy, but have quantized energy states.
4. they only orbit at certain allowed distances from the nucleus.
118
Explain the phenomenon of jumping and dropping of an electron?
if an electron absorbs energy that is exactly equal to the different in energy between its current level and the one available at a higher level, it jumps to that higher level.
If an electron emits a photon with an energy exactly equal to the difference between its current level and the one at the lower energy.
119
Bohr's model predicted that elements have line spectra instead of a continuous spectra. True/ False
True
120
An electron can absorb any amount of energy?
False, electron can only gain or lose specific amount of energy due to their quantized nature of energy levels
121
Define ground state? excited state?
It is where electron is initially, lowest possible energy level n = 1
when electron absorbs a photon and it jumps to a higher energy level
122
Excited electrons relax to the ground level in large jumps? t/f
False, they gradually lose energy and come to the ground state
123
Formula for energy levels of electrons?
E n = (-2.178 x 10 ^ -18) / n 2
124
What is Bohr's atom
an atom that contains only one electron
125
Limitation of Bohr's model of atom
cannot predict the line spectra of multiple electrons, cannot explain the electron-electron interactions
126
What does quantization of atoms describe?
Shell, sub-shell, orbital and spin number
127
higher shell electron has a greater amount of energy? T/F
True
128
Define orbital
3-D region around the nucleus where the electron is most likely to be found.
129
Define subshell
A subshell in an atom contains one or more orbitals with the same energy. It also describes the shape and energy of the orbitals. Subshells are s, p, d, f
130
what are degenerate orbitals
one or more orbitals of the same energy
131
orbitals of same energy have same 3-D orientation in space? T/F
False. The number of orientation increases by two in each successive subshells. 1 in s, 3 in p and so on
132
The number of orientations increases by two in each successive subshell? T/F
True, s subshell contains one orientation and p contains three
133
Describe the shape of s and p orbitals
s subshell has one spherical symmetrical orbital and p has three orbitals with different spacial orientations
134
describe electron spin states
two possible spin states (electron's intrinsic magnetism). orbital with two electrons, one spins up and one spins down
135
3 rules of electron configuration?
Aufbau principle: electrons occupy the lowest energy orbitals available
Hund's rule: electrons in the same sub shells occupy available orbitals singly before pairing up
Pauli principle: there can be no more than 2 electrons in a given orbital
136
maximum numbers of electrons in s, p, d, f subshell?
s has 1 possible orbital orientation, and there can be no more than 2 electrons in any given orbital
2 x 1 = 2 elections
p has 3 possible orbital orientation,
2x 3 = 6 electrons
d has 5
2 x 5 = 10
f has 7
2 x 7 = 14
137
Define diamagnetic
an atom that has its all of the electrons paired is called diamagnetic. these electrons cancel out each other's magnetic field leaving the atom with no magnetic field. As a result, the atom will be repelled by an externally produced magnetic field
138
Define paramagnetic
when an atom's electrons are not all spin-paired. these atoms are attracted to external magnetic field
139
difference between a period and group on the periodic table
period is horizontal row and group is the vertical column
140
difference between a period and group on the periodic table
period is horizontal row and group is the vertical column
141
Additional rules for d and f period while counting the configuration
for d block of period, subtract 1 from period number, outermost electrons are in 3d instead of 4d and for f period block, subtract 2 from the period number, instead of 8f it would be 6f
142
Name some atoms with anomalous electron configurations. (anticipated electron configuration is not one observed)
anomalous atoms can achieve a lower state of energy by having a filled or half filled d shell. These are chromium group, copper group atoms, pg -73
143
define isoelectronic?
F - has the same electron config. as Ne gas after gaining an electron. Atoms with the same configurations said to be isoelectronic.
When an atom becomes an anion, move right on the periodic table
When an atom becomes a cation, move left on the periodic table
144
Define the process of ionization (electrons being removed) from d group
To form a cation, atoms will always lose their valence electron first from s before they lose it from d
145
List special names for a group in periodic table
Group I : Alkali metals ( reducing agents)
Group II: Alkaline earth metals ( reducing agents)
Group VII: Halogens (oxidizing agents)
Group VIII: Noble gases
s, p blocks: representative elements
d blocks: transition metals
f blocks: rare earth metals
146
Define metalloids
Elements that posses the qualities of both metals and non metals. Example: B, Si, Ge, As, Sb, Te, Po
147
Define shielding
Each filled shell between the nucleus and the valence electrons shields the valence electrons from the full effects of the positively charged protons in the nucleus. Z eff: effective nuclear charge
148
Describe the atomic trends in the periodic table (atomic radius, ionization energy, electron affinity, electronegativity, acidity)
Atomic radius:
left to right: atomic radius decreases because more protons are applied higher effective nuclear charge on the electrons
top to bottom: atomic radium increases because more shells are being added and shielding increases
cation < neutral atom < anion
ionization energy: energy required to remove an electron. IE 1 for energy to remove the least tightly bound electron. IE2: energy to remove least tightly bound from the cation. IE2 > IE1
left to right and bottom to top - energy increases because the valence electrons are more tightly bound.
noble gases have large IE
Electron affinity: energy associated with add an electron. energy released: negative, energy absorbed: positive
halogens have large negative EA, more stable: release of energy
noble gases and alkaline earth metals have positive EA as adding an electron destabilizes them
more negative as we right and up (there are exceptions like noble gases)
Electronegativity : tendency to attract electrons
left to right: ENV increases
top to bottom: decreases
F>O>N=Cl>Br>I>S>C=H
Acidity: how well the compound donates protons
left to right: increases because more ENV more stable anion
top to bottom: increases, as the size increases
149
What does formal charge tell us? What is the formula?
If the atoms are sharing their electrons in the best way possible. This happens when the formal charge is as low as possible. FC = valence e - 1/2 bonding e - lone paired e (individual). Negative formal charges on the most electronegative elements
150
Describe resonance structure
These structures are often needed when there are double or triple bonds in molecules along with one or more lone pairs of electrons.
151
Define resonance hybrid
an average of the equivalent or non-equivalent lewis structures. The dotted line in the hybrid signifies a bond and a half
152
Define bond length
the distance between two nuclie that are bonded to one another
153
Define bond dissociation energy
energy required to break the bond homolytically (where one electron of the bond being broken goes to each fragment of the molecule and two radicals form)
154
Define heterolytic bond cleavage
both electrons that make up that bond end up on the same atom forming an anion and a cation.
155
Define bond order?
number of bonds between adjacent atoms, single bond = 1, double = 2, triple = 3
156
relationship between bond length and bond order
higher the bond order, shorter and stronger the bond
157
Carbon carbon bond lengths can be compared to carbon-oxygen bond lengths? T/F
False, bevause of the varying atomic radii the bond length and dissociation energy comparisons should be between similar bonds. Carbon - carbon can be compared to carbon-carbon only
158
describe the relationship between bond length and s and p charaters
the greater the s character, the shorter the bond because s-orbitals are closer to nucleus. p character leads to a longer bond that is farther from the nucleus
159
How is covalent bond formed?
Covalent bond is formed between atoms when each contributes one or more of its valence electrons. These electrons are shared by the atoms to help complete the octet.
160
When is a covalent bond polar and non-polar?
Polar bond when the electron density between two nuclei is uneven or when there is a greater difference between the ENV of the bonding atoms.
Non-polar when the electron density is even and there is a little difference between the ENV of two atoms that are bonded to each other.
161
what is a coordinate covalent bond?
one atom donating both the shared electrons in a bond. example NH3 bonding with BF3 in which N donates both of its lone pair to make a bond
162
what is Lewis base and Lewis acid?
a molecule that donates a pair of electrons is called Lewis base aka ligand aka nucleophile (nucleus loving). base is a diner
a molecule that accepts a pair of electrons is called Lewis acid aka electrophile (electron loving). acid is a acceptor
163
When a covalent bond breaks, the electrons from the ligand split between two molecules. T/F
False, electrons that come from a ligand leaves with a ligand.
164
How do you identify Lewis base?
Lewis base is a molecule with a pair of non-bonding electrons
165
What is an ionic bond
when two molecules are held together by the electrostatic attraction between a cation and anion.
166
What is one rule of VSEPR THEORY
SINCE ELECTRONS REPEL ONE ANOTHER, ELECTRON PAIRS MOVE FAR AWAY FROM EACH OTHER WHETHER THEY ARE BONDING OR NON-BONDING
167
what are some trends of ionic bonds
metal and non mental should have a big difference between their ENV to make an ionic bond
strength of an ionic bond is related to the charges on the ion. bigger charge, greater strength
the strength decreases as the ionic radii increase
168
CHARACTERISTICS OF A LINEAR SHAPE
ANGLE IS 180
169
WHAT ARE ELECTRON GROUPS
ANY TYPE OF BOND AND LONE PAIRS
170
WHAT DOES TOTAL NUMBER OF ELECTRON GROUP ON THE CENTRAL ATOM DETERMINES
THE BOND ANGLES AND ORBITAL GEOMETRY
171
IS ORBITAL GEOMETRY SAME AS MOLECULAR GEOMETRY?
NO, MOLECULAR GEOMETRY AKA SHAPE CHANGES WITH LONE PAIR INTO BENT AND IS NOT SAME AS THE ORBITAL GEOMETRY
172
What is the value of s character and p character in so, sp2 and sp3 hybridization?
sp - 50% s and 50% p
sp2 - 33% - s and 67 % p
sp3 - 25 % s and 75% p
173
what are the bond angles of three hybridization groups?
sp - 180
sp2 - 120
sp3 - 109.5
174
review khan academy notes on hybridization and steric number
175
What results in a polar molecule
When there are unsymmetrical polar bonds present in a molecule so they don't get cancelled out. The atoms connecting the the central atom should have unequal ENV
176
List two forces that hold liquids and solids
Intermolecular molecular forces such as dipole-dipole and London dispersion forces
177
define intermolecular forces
weak interactions that take place between neutral molecules
178
define ion dipole forces
polar molecules are attracted to ions and create ion-dipole forces
179
define dipole dipole interactions
attraction between positive end of the polar molecule and the negative end of the polar molecule
180
define dipole induced dipole force
a permanent dipole in a molecule may induce a dipole in a neighbouring non polar molecule producing dipole induced dipole interactions
181
Define LDF
an instantaneous dipole in a non polar molecule induces a dipole in neighbouring non polar molecule. This results in LDF which are very weak and a default force in all atoms or molecules
182
How is molecular weight related to polarity
as the molecular weight increases, the polarity also increases
183
what is the relationship between dispersion forces and atomic size
direct, as the atomic size increases the dispersion forces also increase
184
How would stronger intermolecular forces effect meeting points, boiling points, viscosities and vapour pressure
high melting and boiling points, high viscosity, and lower vapour pressure
185
what are van Der Waals forces collectively and individually referring to
collectively - dipole-dipole, hydrogen bonding and LDF
individually - LDF
186
What are the 2 conditions of a hydrogen bonding
1. a molecule must have a covalent bond between H and either NOF
2, the another molecule must have a lone pair of electrons on NOF atom
187
The boiling points of NOF bonded with H containing compounds is similar to other elements found in the similar groups?
T/F
False, the boiling point of the hydrogen containing compounds with NOF is much higher than the atoms found in the same group.
188
what is vapour pressure
pressure exerted by the gaseous phase of the liquid that evaporated from the exposed surface of the liquid
189
relationship between vapour pressure and IMF and boiling point
weaker the forces, higher the vapour pressure and more easily it evaporates
indirectly related to boiling point. the higher the boiling point the Lower the vapour pressure, it doesn't boil easily.
190
what substances are said to be volatile
substances with high vapour pressure
191
relationship between vapour pressure and temperature
Direct
192
Define ionic solids
solid held together by electrostatic attraction between cation and anion in a lattice structure.
Strong and solid at room temp
intermolecular forces are similar to intramolecular forces
193
In an ionic solid, what determines the strength of the bond: charge of the ion or the size of the ion?
Charge of the ion
194
Define a network solid
atoms are connected in a lattice of covalent bonds (all interaction between the atoms are covalent bonds)
only has intramolecular forces
hard solid, very strong at RT
195
define metallic solids and conduction electrons
covalently bound lattice of uncle or inner shell electrons with at least one freely roaming valence electron called conduction electron.
excellent conductors of heat and electricity
malleable and ductile
almost all are solid at RT
196
Molecular solids
particles are molecules that are Held together by intermolecular interactions - D-D, hydrogen bonding and LDF.
weaker than ionic, network or metallic bonds
liquid gasses at RT, solids if their strength of intermolecular force increases
197
What is thermodynamics?
Transformation of the energy from one form to the other
198
describe the zeroth law of thermodynamics
if two systems are in thermal equilibrium with a third system, then the two initial systems are in thermal equilibrium with one another.
when systems are in thermal equilibrium with one another, their temperatures must be the same
when bodies of different temperature are Brought together, the heat will flow from body with the higher temperature to into the body with lower temperature.
199
Describe the first law of thermodynamics
the total energy of the universe is constant. energy may be transformed from one form to another but it cannot be created or destroyed
isolated system has constant energy - first law
work can be put into a system to increase its overall energy.
200
Describe three distinct designations to describe energy flow
system - the thing we are studying
surroundings - everything else
thermodynamic universe - system +surroundings
201
when the energy flows into the system from the surroundings, the energy of the system --- and the energy of the surroundings ----.
201
when the energy flows into the system from the surroundings, the energy of the system --- and the energy of the surroundings ----.
202
when the energy flows into the system from the surroundings, the energy of the system --- and the energy of the surroundings ----.
increases, decreases
203
when the energy flows out of a system into the surroundings, the energy of the system --- and the energy of the surroundings ----.
decreases, increases
204
Define enthalpy
measure of heat energy that is released or absorbed when bonds are broken or created during a reaction under constant pressure
205
2 principles of enthalpy
when bonds are formed, energy is released change in H < 0
when bonds are created, energy is absorbed change in H >0
206
how do you find enthalpy of the reaction?
Enthalpy of products - enthalpy of reactants
207
Is enthalpy also known as heat of reaction (delta H)? t/f
True
208
Define exothermic and endothermic reactions
exothermic: products have a stronger bond than reactants, more energy is released in making the product bonds than was put in to break the reactant bonds. energy from the overall system is released.
Endothermic: products have a weaker bond than reactants, more energy is put in to break the reactant bonds than it is released.
209
Are products and reactants higher or lower in energy in an endothermic reaction? exothermic reaction?
Endothermic: products are higher in energy state than reactants, H is positive
exothermic: products are low in energy than reactants, H is negative
diagram on pg - 124
210
Which of the following does not contribute to the change in enthalpy?
phase change, formation of stronger intermolecular forces, breaking covalent bonds or a catalyst
A catalyst lowers the activation energy but doesn't effect the enthalpy in any way
211
What is standard heat of formation?
It is the amount of energy required to make one mole of a compound from its constituents elements in their natural or standard state. It is donated by ΔHfo. The ΔHfo of the elements in their standard form is 0
212
ΔHfo for C (S) (graphite) is zero. True or false
True
213
What is ΔHfo for diatomic elements? (O2, H2, CL2)
Zero
214
Why is it that ΔHfo for O2 is zero but for O ΔHfo = 349 Kj/mol?
Because it takes energy to break the double bonds of O2
215
What does it mean if ΔHfo is positive? negative?
Positive : input of heat is required to make that compound from its constituents
negative: making the compound from its constituents gives off energy
216
How do you find ΔHo reaction?
subtract heat of reaction from heat of products
217
Why is ΔHfo for Br2 (g is not zero?
Because under standard conditions, br2 is liquid and not gas
218
What is hess's law of heat summation
if the reaction occurs in several steps, then the sum of energy absorbed or given off in all the steps will be the same as that of overall reaction
219
ΔH is dependent on the pathway of the reaction? True or False
False, ΔH is independent of the pathway of the reaction due tp Hess's law pg 127
220
Enthalpy is energy stored in the chemical bonds of the compounds? T/F
True
221
Describe the phenomenon to create and break a bond (what should be endothermic and exothermic)
breaking a bond should be endothermic
making a bond should be exothermic
if it is the opposite then the bonds would be unstable and immediately dissociate
222
What is bond dissociate energy
energy required to break a bond homolytically. every bond has characteristic enthalpies to denote this1
223
if a question provides bond enthalpies, how would you find ΔH reaction?
ΔH rxn = sum of BDE bonds broken - sum of BDE bonds formed
224
if stronger bonds are being made than those broken the energy would be positive? T/f
False, it would be negative
225
if stronger bonds are being broken are being broken then the reaction would be exothermic? t/f
false, it would be endothermic
226
reaction enthalpy by using heat of formation and bond dissociation energy is not the same. Why?
bond energies are reported as an average of many example of that type of bonds whereas heat of formation are determined for each individual chemical compound.
227
What is the second law of thermodynamics
disorder of the universe increases in a spontaneous process. All processes tend to run in the direction of maximum disorder.
228
Define entropy
entropy measures disorder or randomness. direct relation. represented by S
229
Change in entropy formula?
S products - S reactants
230
When is 🔼 S positive or negative
S is positive when the randomness increases and order decreases
S is negative when the randomness decreases or the order increases
231
As the molecule becomes more organized, the entropy decreases? T/F
True
H2CO3 ⇌ CO2 + H2O
the entropy of forward reaction is positive/increasing
for reverse reaction, entropy is decreasing
232
State any general predictions for entropy
gasses have more entropy than solids and liquids
liquids have more entropy than solids
two moles have more entropy than one mole
particles in a solution have more entropy than in an undissolved solution
the value of △ S for forward reaction is same as the reverse but opposite
233
review examples from pg-130 to 132
234
Describe third law of thermodynamics
absolute zero is a state of zero-entropy. at absolute zero, thermal energy is absent and only at least energetic thermodynamic state is available. There is no randomness to the system S=0
235
What is Gibbs free energy
it is the energy that is available to do useful work from a chemical reaction
236
how do you determine spontaneity of the reaction
using entropy, enthalpy, and Gibbs free energy
237
Predict spontaneity if △H is positive and △S is negative
non spontaneous. products have more energy and less disorder
238
Predict spontaneity if △H is negative and △S is positive
Spontaneous, products have less energy and more disordered
239
If the signs are same for △H and S, then G is calculated. True/False
True
240
Formula for △G
△G = △H - T△S
241
Predict spontaneity
△G < 0
△G = 0
△G > 0
negative = spontaneous in forward direction
0 = equilibrium
positive = non spontaneous in forward direction
If △G for forward direction is positive, then the reverse reaction is negative therefore the reverse reaction is spontaneous.
242
relationship between △G and temperature
direct
243
At low temperature, the entropy has the same effect on free energy
False, at low temperatures entropy doesn't have that much influence
244
in general universe tends towards increasing disorder and stable bonds, what is the sign for H and S
Increasing disorder - positive △S
Stable bonds - negative △H
245
What is the use of reaction energy diagrams
the graph plots the free energy of the total reactions versus the conversion energy of reactants into the products
246
define activation energy
the energy that reactants require to overcome the activation barrier
247
higher activation energy = slow speed of reaction towards equilibrium. T/F
True and vice versa
248
A large Ea means a large K eq. T/f
True
249
Does a spontaneous reaction mean the reaction would taking place rapidly
No, spontaneous reaction means that under standard conditions the formation of a compound is favoured. Rea pg -134 last para
250
A reverse reaction has the same magnitude for all thermodynamic values but the opposite sign. name these values
△H. △G, △S
251
if you are given the graph of a forward reaction, how would you derive the graph of the reverse reaction
it is the mirror image of the forward reaction
252
Name one value that would different for forward and reverse reactions
Ea would different. forward rxn - Ea = G of reactants - activated complex
but in reverse rxn - Ea = G of products - activated complex
253
define temperature
measure of internal kinetic energy that molecules have
254
Relationship between kinetic energy and entropy
Direct, more kinetic energy more entropy
255
define phase change
breaking or forming of intermolecular interactions
256
diagram for phase transitions
pg 145
heat absorbed, kinetic energy increases, entropy increases during fusion (melting of solid), boiling and sublimation
Heat is released, entropy decreased, kinetic energy decreased during condensation, crystallization (liquid to solid) and deposition (gas to solid)
257
define heat of transition
the amount of energy required to complete a phase transition
258
define heat of fusion
heat that must be absorbed to change a solid into a liquid
259
define heat of vaporization
energy absorbed when a liquid Changes into gas
260
formula for heat required for a phase transition
q = n x △H phase change
261
heat of transition can be in joules and cal/g. t/f
True
262
define calorie
amount of heat required to raise the temperature of 1g of water by 1 degree C
263
1 cal =? J
4.2 J
264
two things that a change of phase depends upon
type of substance and amount of substance
265
when a substance absorbs or releases heat, what two things can happen
either its temperature changes or it will undergo a phase change but not both at the same time
because the energy absorbed is used to break the bonds between the molecules during the phase change and not to increase the kinetic energy of the sample, so the temperature doesn't change `
266
relation between heat capacity constant and specific heat
C =mc
q = CT
q = mct
267
define specific heat
it is an intrinsic property of the substance that tells how resistant it is to changing its temperature
268
relationship between temperature and specific heat capacity
inverse t = q/mc.
269
substance with high specific heat will undergo high change in temperature than a substance with lower specific heat. T/F
False it the opposite
270
The numerical value for specific heat is different in kelvin and Celsius. T/f
False
271
draw phase transition diagram
pg 149
272
what are the horizontal and vertical axes of the heating curve
horizontal - heat aded
vertical - temperature
273
What does a long flat line represent on the heating curve
high value of heat of transition
274
substance's heat of vaporization is smaller than heat of fusion?T/F
False, it is the opposite
275
What is the slope of temperature change lines on the heating curve
1/C, reciprocal of substance heat capacity at the phase
276
pressure influences the phase of a substance. T/F
True
277
what does a phase diagram show
how phases are determined by temperature and pressure pg-151
278
in the phase diagram, when are two phases in equilibrium
at the boundary lines
279
what phase is favoured at low temp and high pressures
solid
280
what phase is favoured at high temperature and low pressure
gas
281
What is a triple point in phase diagrams
where all three phases exist simultaneously in equilibrium and therefore, all phase changes are happening simultaneously
282
what is a critical point on phase diagrams
it marks the end of liquid gas boundary beyond which a substance is called supercritical fluid (gas and liquid phases are not distinct) and no amount of increased pressure can force this substance into liquid phase
283
What is different about water phase diagram
water is denser in liquid phase than solid phase therefore the solid liquid boundary line has a slight negative slope.
For water, increase in pressure favours the liquid phase and not the solid phase
284
What are the most important properties of gas
pressure, volume and temperature
285
What are 4 laws of kinetic-molecular theory
1. the modules of gas are so small compared to the average spacing between them that the molecules themselves take up no volume
2. The molecules of gas are in constant motion, moving in straight lines at constant speeds and in random directions between collisions. The collisions of the molecules with the walls of the container define the pressure and all these collisions are elastic
3. since each molecule moves at a constant speed and all the collisions are elastic. the molecule of gas experiences no intermolecular forces.
4. The molecules of a gas span a distribution of speed and the average kinetic energy of the molecules is directly proportional to the absolute temperature
286
If a gas satisfies all the conditions of kinetic molecular theory, what is it called
ideal gas
287
Most real gases behave like ideal gas. t/f
True
288
What is SI unit for volume in chemistry
cm3 and L
289
1 cm3 = ?L
1000L
290
What unit is used to measure gas temperature
Kelvin
291
T in K = T in C +-----
273.15
292
At 0 Kelvin, what is the entropy of gas?
0
293
What is the SI unit for pressure
Pascal, but it very small for measurements so other units are used
294
What are some other units that are used for pressure
1 atm = 760 tor = 760 mm hg = 101.3 KPa
295
Define Standard temperature and pressure
STP means temperature is 0 degree Celsius (273.15 K) and a pressure of 1 atm
296
What would be the reading of a barometer filled with a liquid of lower density than Hg if at that moment another nearby Hg barometer reads 752 mm Hg?
Look the the picture of a barometer, greater than 752mmhg
297
How do pressure, temperature and volume of an ideal gas relate to one another
Pv=nrt, as most gas behave as ideal gas this law can be applied to them
298
What is the value of R in pv =nrt
0.0821
299
Describe Charles's Law
Value is proportional to temperature. If the pressure is to remain constant, then a gas will expand when heated and contract when cooled. If the temperature of the gas increases, the molecules will move faster and hit the wall of the container wth more force
300
What is Boyle's law
Pressure is indirectly proportional to volume. if the volume decreases, the molecules have less space to move around =, they will collide with the walls of the container more often and the pressure increases
301
Presssure is proportional to temperature. T/F
True. if the temperature increases, the molecules will move faster and collide with the walls more often
302
In Charles law, name the variable that is constant
n and P
303
In Boyle's law name the variable that is constant
n and T
304
What is combined gas law
combined Boyle's and Charles's law where n is constant
305
define Avogadro's law
If two equal volume containers hold gas at the same temperature and pressure, then they contain the same number of particles regardless of the identity of the gas.
306
How would you put Avogadro's law into an equation
V/n = k
307
What volume does an ideal gas occupy at STP where T = 0 degree Celsius and P = 1atm
22.4 L , see the calculation at pg 165
308
review how to find the limiting reagent
309
What two assumptions from the kinetic molecular theory deviate from the idea gas behaviour.
1. the particle of gas experience no intermolecular forces. P real < P ideal under fixed volume
2. the volume of the gas is negligible compared to the volume of the container. V real < V ideal under fixed pressure
310
When does a gas behave ideally, in terms of pressure, temperature and volume, intermolecular forces and weights
high temperature, low pressure, high volume, low intermolecular forces and smallest weights
311
What is Van der Waals equation
equation accounts for the differences in observed real gas behaviours while maintaining the same gas law
pg 168 for equation. (P + an2/v2) (V- nb) = nrt where A is the intermolecular forces and B is the volume
312
Van der Waal constants, a and b, are smaller for gases with large intermolecular forces and molecular weights? T/F
False
313
Describe Dalton's law of partial pressure
total pressure is the sum of the partial pressure of all the constituents gases.
314
How do you find the mole fraction?
gas molecule of individual gas / total gas molecules
315
how do you find the partial pressure of the gas given the total pressure
mole fraction x Total pressure
316
what is effusion?
the escape of a gas molecule through a very tiny hole into an evacuated region is called effusion
317
What is rms while finding masses from average kinetic energy
root mean square, the square root of the mean of the square of speed
318
What is graham's law of effusion?
rate of effusion of Gas A / rate of effusion of Gas B = ⎷molar mass of Gas B / Molar mass of gas A
319
molecule of gas at the same temperature would have the same average speed but different average kinetic energy? T/F
False, same KE but different average speed
320
What is a reaction intermediate
a substance that is produced in one elementary step and consumed in the other
321
Intermediates are part of the overall balanced reaction?
False
322
What is the rate determining step of an reaction?
the slowest step in the process determines the rate
323
If the last step of the reaction is slow, the intermediates would pile up?
False, the intermediaries will go back and forth between reactants and products
324
What is the formula for rate in general
rate = △[A]/△t
325
Define rate of the reaction
how fast the reactant are being consumed or how fast the products are being made
326
Name three factors that effect the reaction rate
how frequently the reactant molecules collide
the orientation of the colliding molecules
their energy
327
What is activation energy
the minimum energy required by the reactants during the molecular collision for the reaction to proceed to products
328
what is activated complex
when reactants have the necessary activation energy they reach a high energy but short lived transition state called activated complex
329
draw a reaction coordinate diagram
330
What is the energy maximum in the reaction coordinate diagram
Activated complexes
331
An intermediate has more energy than reactants and products?
True
332
What are the three variables that increase the rate of reaction
temperature, lower activation energy and high concentration of reactants
333
G has no effect on the rate fo reaction because thermodynamic factors and kinetic factors do not effect each other?
true
334
How does a catalyst speed up a reaction
by speeding up the rate determined step or lowering the activation energy of the rate determining step (energy of the highest transition state). Ea of forward and reverse reaction is lowered
335
Catalyst changes with the reaction?
it undergoes a temporary change but always returns back to its initial state so it remains unchanged
336
catalysts are included in the overall reaction?
False
337
Catalyst only changes the activation energy and not the equilibrium or thermodynamic quantities of the reaction?
True
338
How would you find the rate law of a reaction?
rate = k [A] ^x [B]^y, k = the rate constant
339
You can figure out the orders of reactants by looking at the balanced equation
False
340
Formula to find the rate constant
k = rate / [A][B]^2
341
What is Arrhenius equation
k = Ae ^ - (Ea/RT) or k = ln - (Ea/RT)
342
k = ln - (Ea/RT), how would adding a catalyst effect the Arrhenius equation
adding the catalyst, lowering the Ea, increase the T and Increase k
343
rate increases by a factor of 2 to4 for every 10 degree Celsius increase in temp?
True
344
rate = k [a][b], how do the units of k change with order
rate has a unit of M/s, first order reaction for both, M/s /M/M = 1/M.s
345
What is equilibrium
When the forward reaction and reverse reaction come into a balance
346
At equilibrium forward and reverse reaction occur at different rates?
False
347
The overall conc of reactants and products remain the same but at molecular level they are different?
True
348
Equilibria occurs for open systems?
False, Closed systems
349
equation for equilibrium constant
k eq = [C]^c [D]^d / [A]^a [B]^b
350
What is mass action ration
Where square brackets represent the molar conc. at equilibrium [C]^c [D]^d / [A]^a [B]^b
351
What is not included in the equilibrium equation
solids, pure liquids and solvents
352
The value of K eq is constant at a given temperature
True
353
What does keq>1, keg<1 keq=1 mean?
Keq >1 - reaction favours the product
k <1 rxn favours the reactants
k = 1 reaction has equal amounts of reactants and products
354
What is the reaction quotient (Q)
if the reaction is not at equilibrium then the same equation for Keq is known as Q
355
How does comparing Q and Keq tell us how the reaction would proceed
K = Q, equilibrium
Q < K -forward
Q > K - reverse
Q → K ← Q
Q< k, rxn forward towards k
Q>K rxn reverse, towards k
356
What is le chatelier principle
system at equilibrium will try to neutralize any imposed change or stress to reestablish equilibrium
357
How does change in volume of the reaction container effect the equilibrium of the gas
If the volume is reduced, the pressure increases and the reaction favours the side with small amount of total moles
if the volume is increased, the pressure decreases and the net reaction favours the side with greater total moles
only applicable to gas equilibrium
358
Describe changing the temperature with respect to le chatelier principle
Temp can be seen as a reactant or product in the Rxn based on whether it is exo or end
removing heat favours exothermic rnx
adding heat favours endothermic tnx
359
Changing temperature, pressure and concentration will change the Keq of the reaction? T/F
Not all, only temp will change the Keq
360
According to le chatelier principle how does adding an inert gas effect the equilibrium
does not effect the equilibrium
361
What is the case when adding an inert gas would change the equilibrium according to the le chatelier principle
inject inert gas into constant pressure container one with movable piston, some extra gas particles will push against the piston. they will increase the volume and decrease the partial pressure and would cause a shift in equilibrium
362
Would adding a catalyst to the reaction effect equilibrium
No
363
What is a solution
when one substance dissolves into another
364
what is dissolution
process of dissolving
365
Define solvation
when solvent molecules surround the solute molecules
366
What is hydration
When water is used as a solvent and the molecules surround the solutes
367
Solutions can be made out of any three phases of matter?
True
368
Define aqueous solution
when water is the solvent
369
How can you tell what solutes are soluble to what solvents
like dissolves like (intermolecular forces)
370
Ionic substances dissociate into ions?
True
371
What are electrolytes
Free ions in a solution that conducts electricity
372
Do all ions dissociate fully?
No
373
What are strong and weak electrolytes
solutes that dissociate completely are strong and those who remain ion-paired are weak
374
What are non-electrolytes
Covalent bonds that don't dissociate at all
375
what is van't Hoff factor/ ionization factor
how many ions one unit of substance will produce
376
what is the ionization factor for C6H1206, NACL, HNO3, CACL2
1 Because non-electrolyte
2 na and cl
2, h no3
3, ca and 2 cl-
377
At molar solubility precipitation and dissolution occur at the same time
True
378
What is molarity
# n / volume
379
What is solubility
Amount of solute that will saturate a solvent
380
What are the phase solubility rules
solid solubility liquid in water with temp
gas solubility decreases in liquid with increasing temp
gas solubility increases in liquids with increasing pressure
381
What are salt solubility rules
All group 1 are soluble
all nitrates, percolates and acetates are soluble
lead, silver and mercury are insoluble unless they are nitrate, percolate or acetate
382
Define solubility product constant
the extend to which a solid will dissolve in water
383
What is molar solubility
the number of moles of a salt that will saturate a solution
384
What is the ion product of the solubility reaction
reaction quotient when solution is not at equilibrium
385
Qsp < K
Qsp >K
Qap = K
more salt can be dissolved
precipitation
solution is saturated
386
Adding a ligand to complex ions would increase/decrease the solubility of the ions
Increase the solubility and forms a salt
387
One biological application of complex ion formation (review ICE tables khan academy)
Metal chelation therapy where metal chelation agent called (one word )-- ehtylene diamine tetra acetic (EDTA) is used for lead poisoning
388
What is the equation that related Q/K to G
△G = △G degree + RT ln Q
0 = △G degree + RT ln K, G = 0 AT EQUILIBRIUM
389
WHAT IS THE DIFFERENCE BETWEEN G DEGREE AND G
G DEGREE IS THE RELATIVE PROPORTION OF REACTANTS AND PRODUCTS AT EQUILIBRIUM
G IS THE SPONTANEITY OF THE REACTION
390
WHEN G DEGREE < 0, K > 1, WHAT IS FAVOURED
G DEGREE = 0, K = 1,
G DEGREE >0, K < 1,
PRODUCTS
EQUILIBRIUM
REACTANTS
391
Define Bronsted Acid and Base
Bronsted acid are proton donors and bases are proton acceptors
392
Define Lewis base and acid
Lewis base are electron base donor and acid are electron pair acceptor
393
No matter what definition of acid or base you use, the acid and base remain the same? Lewis acid would be the same as the bronsted acid
True
394
what are conjugate acids and bases
when Bronsted acid donates a proton, the remaining structure is called conjugate base of the acid.
when the base accepts a pair the new species is called conjugate acid of the base
394
what are conjugate acids and bases
when Bronsted acid donates a proton, the remaining structure is called conjugate base of the acid.
when the base accepts a pair the new species is called conjugate acid of the base
395
how do you differentiate between strong and weak acid
strong acid dissociates in water completely
396
Describe the acid ionization constant value with respect to 1 to describe a strong or weak acid
Ka>1
ka<1
Ka > 1, strong acid
Ka <1 weak acid
397
Name 6 strong acids
HI, HCL, HBr, HClO4, H2so4, HNO3
So I Brought No Clean Clothes.
398
A strong acid would not have a stable conjugate base?
False, more stronger the acid, more stable the base
399
A strong acid would not have a stable conjugate base?
False, more stronger the acid, more stable the base
400
Why is HF not a strong acid
the conjugate base, F- has a smaller radius making it less stable, the weaker acids have less stable conjugated bases
401
How can you tell if something is a strong acid/base
if K b has a greater value the base is strong
402
Name 4 categories of strong bases
group 1 oxides, group1 hydroxides, group 2 with 4 s orbital and metal amides
403
name two categories of weak bases
one that contain ammonia and amines
404
Strong acid do not have a reverse reaction
True
405
The conjugate base of a strong acid has no basic properties in water
True
406
4 statements describing the strength of conjugate acid and bases
Conjugate base of a strong acid has no basic properties in water
conjugate acid of a strong base has no acidic properties in water
conjugate base of a weak acid is a weak base
conjugate acid of a weak base is a weak acid
407
Weaker the acid/base, stronger the conjugate base/acid
True
408
The weaker the acid/base, the less reverse reaction is favoured
False, more favoured q
409
Weaker the conjugate acid, weaker the base?
False, stronger the base
410
What is an amphoteric substance
the substance that can act as an acid or base
411
What is polyprotic acid
substance that has more than one proton to donate
412
The conjugate base of a weak polyprotic acid is always amphoteric
True, polyprotic acid such as H2co3 has a base of HCO3- where this conjugate base can donate or accept another proton
413
Every time a polyprotic species donates a proton, it becomes stronger
False
414
Water is amphoteric
True
415
What is auto ionization of water
water reacts with itself acting as base and acid
416
What is the equilibrium expression for auto ionization of water
k w = [h3o+] [OH-]
kw = 1.0 x 10^-14
[H3O+] = 1.0 x 10 ^ -7
[OH-] = 1.0 x 10^-7
417
All equilibrium constants increase as the temperature increases
True
418
What is a pH scale
It measures the conc of H3O ions in a solution
419
Write the expression for pH
pH = -log [H3O+]
H3O+ = 10^-pH
420
When is a solution acidic, neutral and basic based on value of Ph
pH > 7 basic
pH = 7 neutral
pH< 7 acidic
421
What is pOH?
Measure the basicity of a solution
422
formula for POH
pOH = -log [OH-]
10 ^(-pOH) = [OH-]
423
What is the relationship bw [oh-] [h3o+]
Inverse
424
PH + POH = ?
14
425
IF YOU ARE TOLD THAT [H+] = 6.2 X 10 ^-5, HOW WOULD PREDICT THE PH
PH WILL BE IN BETWEEN (5-1 = 4) AND 5
425
IF YOU ARE TOLD THAT [H+] = 6.2 X 10 ^-5, HOW WOULD PREDICT THE PH
PH WILL BE IN BETWEEN (5-1 = 4) AND 5
426
THE ACID WITH A HIGH PKA VALUE IS A STRONG ACID
FALSE, ACIDS AND BASES WITH SMALL PKA VALUE ARE STRONGER
427
Ka x Kb = ?
where Ka is acid and K b is a conjugate base
1 x 10^-14
428
pKa+pkb = ?
14
429
`What is ⎷10?
3.2
430
Weak acid at equilibrium has a greater conc of undissociated ion than hydrogen ions at the product side.
True
431
When is x dded or subtracted negligible in ICE tables
When Ka < 10^-4
432
what is a neutralization process
when acid and base react together to make water and salt
432
what is a neutralization process
when acid and base react together to make water and salt
433
Taking an antacid to relieve excess stomach acid is an example of what type of reaction
neutralization
434
Are neutralization process ends or exothermic
exothermic
435
What is the formula for neutralization
a x [A] x Va = b x [B] x Vb
a is number of hydrogen and b is the number of hydrogen a base can accept
436
what is a salt
ionic compound consisting of cation and anion
437
What are the two predictions for the cation and anion in salt to predict whether solution would be acidic or basic
cation that doesn't react with water (group1 and 2 cations) or is a stronger acid than water (nh4 +, Be2+, Cu 2+. Fe 3+, al3+, zn2+, cr3+)
anion that doesn't react with water (conjugate base of a strong acid) or is a stronger base than water (conjugate base of a weak acid)
438
what is a hydrolysis reaction
reaction of the substance with water
439
if water has a strong conjugate base and a strong acid, how would you predict the pH?
compare the ka and Kb values
440
What is a buffer solution
solution that resists changing pH when small amount of acid or base is added. contains a weak acid and its conjugate base or weak base and its conjugate acid
441
How would you know if the buffer solution is effective
if the strong acid or bases added cause less change in pH
442
What is the Henderson-hasselblach equation for buffer solutions for acid and base
pH = Pka + log ( [conjugate base]/ [weak acid])
poH = Pkb + log ( [conjugate acid]/ [weak base])
443
An ideal buffer is solution is where weak acid conc = conjugate base conc. so pka = pH (Desired pH)?
True
444
What is an indicator
a weak acid that undergoes colour change when it's converted to its conjugate base
445
Write an expression with indicator's equilibrium constant and concentration of acidic reactants to predict indicator's colour change
HA + H2O -----> H3O+ + A-
Ka =[H3o+] [A-] / [HA]
[H3o+] / Ka = [HA]/ [A-]
H3O+ > Ka then we will see colour of HA
if H3O = Ka, then we willl se a mix of colour of HA and A-
if H3O +< Ka, then we will see colour of A-
446
What is a general pH range that an indicator changes colours
2 units pKa -1, pKa, Pka +1
read page 249 last para
446
What is a general pH range that an indicator changes colours
2 units pKa -1, pKa, Pka +1
read page 249 last para
447
What is an acid base titration
experimental technique used to determine the identity of an unknown weak acid or weak base by determining their Pka or Pkb
448
what is a titrant during titration
a strong acid or base with known concentration and identity
449
explain the procedure of titration
titrant is added to a solution of unknown base or acid in small amounts and Ph of the solution is recorded.
450
You can titrate strong base with base or an acid with acid
False
451
What is an equivalence point
during titration when the acid completely neutralizes the base or vice versa
452
state the equivalence point for different titrations
weak acid and strong base
weak base and strong acid
strong acid and strong base
1. ph > 7
2. ph <7
3. ph = 7
453
at the beginning of the titration the solutions acts like a buffer
True
454
What is a buffering domain?
the section of titration curve where pH changes very gradually
455
The titration curve for polyprotic acids will have one equivalence point
False
456
What is oxidation number
how many electrons a molecule is donating or accepting
457
What are redox reactions
the reaction in which oxidation numbers of any reactants change are called redox reactions
458
in a redox reaction, the total number of electrons for a reaction changes
False
459
define oxidation and reduction
oxidation is when an atom loses an electron, the oxidation number increases
reduction is when an atom gains electrons and the oxidation number decreases
460
nemonic to remember redox reactions
LEO says GER
461
What is a reducing agent and oxidation agent
An oxidized atom is a reducing agent and a reduced atom is an oxidizing agent
462
What is galvanic cell or voltaic cell
Generates electric current using the work done by redox reactions
463
What are the components of the galvanic cell
anode, cathode, ammeter (measures electric current), salt bridge, electrolyte solution, 2 half cells and wire
464
In the galvanic cell, the metal at anode gets reduced and cathode gets oxidized?
False, anode is oxidized and cathode is reduced
an ox, red cat
465
Write a cell diagram equation where anode - zinc, cathode is copper, inSO 4 solution
zn (S)⎪zn 2+(aq) ⎪⎪cu2+ (aq)⎪cu(S)
466
how do you convert a reduction potential to an oxidation potential
flip it, reverse the sign
467
write the equation for free energy change of a redox reaction
G = -nFE, where F = 96500 C
468
When is a redox reaction spontaneous
When G is negative and Voltage is positive
469
While balancing a redox half reaction, you have to multiply the reductio potential as well?
False
470
What determines a good or poor oxidizing agent or reducing agent
if reduction potential is largely negative, then the reactant is a weak oxidizing agent and products are a strong reduction agent
if the reduction potential is positive, the reactants are strong oxidizing agent and products are weak reduction agent
471
When do we use the Nernst equation for redox
under non standard conditions where temperature and conc of reactants deviate
472
What is a concentration cell
galvanic cell that has identical metal electrodes but have different ion concentrations of the solutions. The electrons go from low conc of the ionic solution to a high conc cell. Low conc is anode and high conc is cathode. the reactions stops when the conc of the solutions are equal
473
a concentration cell has standard conditions?
False, because the solution is the Half cells in not 1 M
474
What are electrolytic cells
these cells use an external voltage source to create an electric current that forces non -spontaneous redox reactions to occur
475
The electrons flow from cathode to anode?
False, anode to cathode
476
What are electroplating
placing a thin layer of metal on top of another material
477
What are 4 differences between galvanic and electrolytic cells
1. electrolytic is non-spontaneous
2. the E is negative
3. Cathode is negative in electrolytic cells
4. anode is positive in electrolytic cells
478
Name 5 similarities voltaic and electrolytic cell
reduction at cathode
oxidation at anode
cations migrate to cathode
anions migrate to anodes
e flows from anode to cathode
479
What are two common rechargeable batteries through redox
lead-acid battery and nickel cadmium battery
480
What is Faraday's law of electrolysis
the amount of chemical change is proportional to the amount of electricity that flows through the cell
