MCAT Chemistry Flashcards
Which particle is more massive: proton or neutron?
Neutron
What is an element’s MASS NUMBER?
sum of the protons and neutrons
What is the symbol, i.e. letter, for MASS #?
A
what is an atomic mass unit? Specifically, what is its actual definition?
What is it’s numerical value?
Unit used to describe the mass of atoms, molecules, and particles. One amu is exactly one-twelfth the mass of a carbon-12 atom, which is ~ 1.66 x 10-24 grams (g)
[Kaplan mcat gen chem]
what is the unit for atomic mass?
amu
what is ‘atomic mass’?
mass of an atom compared to mass of carbon-12 atom
What is ‘atomic weight’ or ‘molecular weight’?
weight, in grams, of 1 mole of an atom or molecule
[NOTE: Kaplan treats atomic mass & atomic weight as two different terms, while EK and college chem textbook uses them interchangeably]
what is another name for an ‘a.m.u.’?
dalton
What is the SI abbreviation for an amu?
u
what is another name/term for atomic weight?
Molar mass
What is a mole?
(What substance in nature is the mole based on?)
It’s the number of particles in a 12-gram sample of carbon-12.
In a periodic table, which groups are called the “periods”? Are the columns referred to as periods, or are the horizontal rows referred to as periods?
Horizontal rows
What is each vertical column in a periodic table called?
Each column called be called a ‘group’ or ‘family’
What are the three main categories that all the elements can be grouped into?
Metals,
non-metals, and
metalloids
What are metalloids?
Elements that share the characteristics of metals and nonmetals
How many groups are there in the periodic table?
18
What 4 characteristics of metals should u know for MCAT (according to EK)?
Metals are:
lustrous,
malleable,
ductile,
and thermally and electrically conductive
What does ‘malleable’ mean?
Easily hammered into thin strips
what does ductile mean?
Easily stretched, easily drawn into wires
Which group are the alkali metals?
Group 1
which group # are the alkaline earth metals?
2
which group # are the halogens?
17
in the periodic table, how is the atomic mass for element determined/derived?
The atomic mass for a given element in the table is actually the weighted average of all the naturally occurring isotopes of the element
What are transition metals??
Groups 3-12 on the periodic table
What are chalcogens?
Group 6A (group 16) elements
what are the most famous of the chalcogens?
Oxygen and sulfur
which of the noble gases are liquid at room temp?
none
True/False:
the mnemonic I Brought Clothes From Old Navy Home refers to the halogens
False!
I, Br, Cl, F are halogens, but O, N, and H are NOT halogens! However, all of these are diatomics!
Do larger or smaller atoms make stronger pi bonds?
Smaller atoms (p. 5, EK Chem)
When transition metals form subshells, which subshell loses electrons first?
S subshell
After the s subshell of a transition metal loses electrons, which subshell loses electrons next?
D subshell
What law/equation do you use to find the force exerted by the nucleus on the outermost electron?
Coulomb’s law
How do you write Coulomb’s law as an equation?
F = *k ** q1 * q2
r2
Do ions with the same exact # of electrons have increasing or decreasing radii as the Z of the nuclei increase?
Decreasing radius with increasing Z, given that the # of electrons stays the same for all the elements being compared
What is Zeff?
Effective nuclear charge
What is effective nuclear charge?
the net positive charge experienced by an outer electron in a multi-electron atom.
What is the equation for Zeff?
Zeff = Z − S
where:
Z is the number of protons in the nucleus (atomic number)
S is the average number of electrons between the nucleus and the electron in question (the number of nonvalence electrons).
How do you use Zeff?
Plug in Zeff for one of the q values, rather than plugging in the actual # of protons
In the periodic table, Zeff (increases/decreases) going from top to bottom and (increases/decreases) going from left to right.
Increases,
increases
In the periodic table, Atomic radii (increases/decreases) going from top to bottom and (increases/decreases) going from left to right.
(p. 7, EK)
Increases,
decreases
what is the name given to the energy required to detach an electron from a neutral atom in the gaseous state?
Ionization energy
X + energy → X+ + e-
In the periodic table, ionization energy (increases/decreases) going from top to bottom and (increases/decreases) going from left to right.
Decreases, increases
What is electronegativity?
The tendency of an atom to attract an electron and thereby form a bond with another atom
What is the name given to the system that’s used to measure electronegativity?
the Pauling scale
What is the highest electronegativity value?
4 (or sometimes 4.1)
which element(s) have the highest electronegativity?
F
What are the electronegativity values for the noble gases?
The noble gases have no electronegativity value
In the periodic table, electron affinity (increases/decreases) going from top to bottom and (increases/decreases) going from left to right.
decreases,
increases
How does ‘dipole moment’ relate to electronegativity?
The greater the difference in electronegativity between 2 bonded atoms, the greater the dipole moment
In the periodic table, metallic characteristics (increases/decreases) going from top to bottom and (increases/decreases) going from left to right.
increase,
decrease
What is a dipole moment?
Dipole moment is the measured polarity of a polar covalent bond.
Dipole moment refers to the quality of a system to behave like a dipole.
What is electron affinity?
X + e− → X− + energy
3 definitions:
1:
The energy released when an electron is added to a NEUTRAL atom that is in a gaseous state. (EK chem)
2:
EA is the amount of energy required to detach an electron from a singly charged negative ion;
An equivalent definition is the energy released when an electron is attached to a neutral atom or molecule. (wiki)
3:
EA is the energy change that occurs when an electron is added to a gaseous atom. EA represents the ease with which the atom can accept an electron. (suhail’s Kaplan p 25)
What is the relationship between Zeff and EA?
Direct relationship
In the periodic table, electron affinity (increases/decreases) going from top to bottom and (increases/decreases) going from left to right.
decreases,
increases
How many base units are there in the SI system?
7
list the 7 quantities being measured by the 7 base units of the SI system:
amount,
electric current,
length,
luminous intensity,
mass,
temperature,
time
What SI unit measures time?
second
which What SI unit measures temperature?
Kelvin
Which SI unit measures mass?
Kilogram
What SI unit measures luminous intensity?
Candela
What SI unit measures length?
meter
What SI unit measures electric current?
Ampere
What SI unit measures amount?
mole
What amount does the prefix Mega- denote?
106
What amount does the prefix Kilo- denote?
103
What amount does the prefix Femto- denote?
10-15
What amount does the prefix nano- denote?
10-9
What amount does the prefix pico- denote?
10-12
What amount does the prefix Deci- denote?
10-1
What amount does the prefix Micro- denote?
10-6
What amount does the prefix Centi- denote?
10-2
What amount does the prefix Milli- denote?
10-3
What is the difference between a molecular formula and an empirical formula?
Empirical formula only shows the lowest ratios between the atoms in the molecule;
molecular formula shows the actual number of atoms in the molecule
What’s up the suffixes –ic and –ous for Cations?
If an element can have more than one ionization state, the -ic was used for the cation with the greater positive charge, -ous for the cation with the **lesser **positive charge.
What’s up with the suffix –ic and –ous for Polyatomic Anions?
Polyatomic anions that come in multiple varieties are named depending on how many oxygens they have.
Which PAIs are named *–ate *and which are named -ite?
“-ate” is given to the PAI with more oxygens, -ite for the PAI with less
order the anion suffixes/prefixes from least oxygens to most:
per- , -ite, -ate, hypo-
hypo-ite,
- ite,
- ate,
per-ate
what is theoretical yield?
Amount of product made when a reaction runs to completion
what is the percent yield formula?
Why is the percent yield formula used?
In reality, a reaction may not run to completion before stopping. So the actual yield of a product will be less than the theoretical yield.
Formula for % yield is:
(actual yield/theoretical yield) * 100 = % yield
What does it mean when the symbol delta (∆) is present above the reaction arrow in a reaction equation?
delta means that heat is added to rxn
what does it mean when you see a reaction equation with two parallel arrows pointing in opposite directions?
It means the rxn can reach equilibrium
What does it mean when you see this symbol ∩ in a reaction equation?
It represents resonance structures
What are the two basic types of solids?
Crystalline and amorphous
What’s the difference between a crystalline solid and an amorphous solid?
Crystalline solids have a specific melting point, and a well-ordered structure of repeating units. These repeating units can each be atoms, molecules, or ions.
Amorphous solid can melt over a temperature range and has no repeating molecular structure.
What are polymers?
Solids that have repeating structural units at the molecular level, BUT can be amorphous solids or crystalline solids.
what determines whether a polymer is made into an amorphous solid or a crystalline solid?
Usually, rapid cooling of liquid polymers results in amorphous solids, slow cooling results in crystalline solids
what are biological examples of polymers?
DNA,
glycogen,
protein
what is ‘bond length’?
average distance between two nuclei in a bond, at which distance the potential energy of the system will be the lowest (an equilibrium between the tug of war created by like and unlike electrical charges)
what are the 4 types of crystals?
Ionic,
network,
metallic, and
molecular
what are network crystals?
they consist of an infinite network of atoms,
held together by polar and nonpolar bonds.
They are made up of atoms sharing their valence electrons.
what are examples of a network crystal?
Diamond,
graphite,
swarovski glass crystal (not like regular glass, which is also silicon dioxide but is an amorphous solid)
what are ionic crystals?
Solids that have oppositely charged ions held together by electrostatic force
what are metallic crystals?
Single-element metal solids that are held together by delocalized electrons
What are ‘molecular crystals’?
solids whose atoms/molecules are held together by weak intermolecular forces
molecular crystals are solids whose atoms/molecules are held together by weak intermolecular forces
what are the above weak intermolecular forces collectively called?
Van der Waals forces
What kinds of Van der Waals forces are there?
Hydrogen bonds,
dipole-dipole forces,
dispersion forces
(http://www.utas.edu.au/sciencelinks/chemincon/files/s1_grow/s1_soils/bonding/index.html#molecular)
In an atom, what is the name of the number assigned to each primary ‘energy level’ or ‘shell’ of electrons?
Principal quantum number
What is the symbol for the principal quantum #?
n
what is the symbol for the azimuthal quantum number?
ℓ
(lower case L)
which LETTER is assigned to label the first shell, or first energy level?
K
What are the letters that follow K?
I.e., what are the letters assigned to the 2nd, 3rd, 4th shells?
L, M, N
What is the overall term/name of the mini-levels within each shell?
Subshell or
sublevel
what is the term/name of the number assigned to each subshell?
Azimuthal quantum number
how many subshells or sublevels exist for the known atoms/elements?
4
what are the names/terms (letters) assigned to these subshells or sublevels?
s
p
d
f
What is the formula that tells you the MAXimum # of electrons that can fill a given shell/energy level?
2n2
What is the equation that tells you the relationship between azimuthal quantum number and principal quantum number?
ℓ = n - 1
what is the name of an area within the atom where an electron can probably be found?
orbital
what is the relationship between an orbital and a sublevel?
Orbital is the subdivision of a sublevel
What is the Heisenberg principle?
It is impossible to know both the position and momentum of an electron at the same time
how many electrons does an orbital hold?
2
what is the Magnetic quantum number?
name of the number assigned to an orbital
what is the number assigned to each individual electron in an atom?
Electron spin quantum number
what is the symbol for an electron spin quantum number?
ms
What is the Pauli exclusion principle?
no two electrons can have the same four quantum numbers
what are the possible electron spin quantum numbers?
1/2
and
-½
what is the Aufbau principle?
A lower-energy subshell is completely filled, before electrons are placed in the next, higher subshell.
What is Hund’s rule?
In the same subshell, Electrons will not completely fill any orbital until:
1: All the orbitals within that subshell contain at least one electron, AND
2: the unpaired electrons in the subshell have parallel spins
when talking about electron spins, what does it mean to say that 2 electrons have ‘parallel’ spins?
They have the same spin (such as ½ and ½, or -1/2 and -1/2)
Why do electrons follow Hund’s rule? Why do electrons prefer empty orbitals to half-filled orbitals? (Kaplan gen chem. Page 30)
Because a mutual repulsion must be overcome for 2 electrons with like charges to exist in the same orbital.
What was Planck’s quantum theory?
EM energy is quantized/discontinuous.
EM energy comes in discrete bundles / units / packets that are related to the frequency of the EM wave.
How is Planck’s quantum theory explained in equation form?
E = hf
What is de Broglie’s formula?
λ = h/mv
what did de Broglie’s equation show?
Electrons and other moving masses exhibit wave characteristics
what phenomenon in nature showed us that light is made up of photons?
The photoelectric effect
who’s famous for the photoelectric effect?
Einstein
specifically, how was the photoelectric effect observed? What specific phenomenon was used by Einstein to demonstrate the photoelectric effect?
Light shining on a metal causes the emission of electrons
how does the photoelectric effect demonstrate the quantized nature of EM?
Einstein showed that light is made up of particles
with regards to the photoelectric effect, what is the ‘work function’?
the work function of a metal is the minimum amount of energy required for the metal to eject an electron when it is hit by a photon
what is the symbol for the work function?
Φ
In the Photoelectric effect, what formula shows us the KE of the ejected electron?
KE = hf - Φ
what is hf in the work function formula?
The KE of the photon that ejected the electron
what are the exact values for temp and pressure at STP?
0 deg Celsius,
1 atm
at STP, what is the avg distance between gas molecules? (EK, p 23)
35 angstrom
what is the mean free path?
Distance traveled by a gas molecule between collisions
what is the mean free path of oxygen at STP?
1600 angstrom
can a nonpolar gas and a polar gas mix homogeneously?
YES
Gas can mix regardless of polarity differences
can gases of different densities possibly separate according to their density? [WITHOUT centrifuges]
If temp is low enough, gravity can cause denser (colder) gases to settle beneath less dense gases
what is the name of the concept/theory that relates to ideal gases?
Kinetic Molecular Theory of Gases
describe an ‘ideal gas’ as put forward by the Kinetic Molecular Theory.
(hint: there are 4 characteristics)
(p. 24, EK chem)
gas molecules have zero volume;
gas molecules exert no forces of attraction or repulsion towards each other;
gas molecules make completely elastic collisions with each other and their container, thus neither gaining nor losing any energy;
the avg kinetic energy of gas molecules is directly proportional to the temperature of the gas.
what is the ideal gas law? Give the equation.
PV = nRT
What is P in the equation for ideal gas law?
Pressure
what is the unit for P (ideal gas law)?
atm
What is the V in the ideal gas law equation?
Give the unit, too.
Volume,
in Liters
what is n, in the ideal gas law eqn?
of moles of gas
what is T, in the ideal gas eqn?
give the unit.
Temperature in Kelvin
what is R in the ideal gas eqn? give the unit
the universal gas constant
(0. 08206 L*atm*K-1*mol-1 or
8. 314 J*K-1*mol-1)
what is the meaning of the term ‘standard molar volume’?
the volume that all gases will have at STP, IF …
they are acting as IDEAL gases
All gases will have the same volume, if they have the same ______, ______, and _______.
temperature,
pressure, and
of molecules
What does Charles’ law state?
Volume of a gas is proportional to temperature,
at constant pressure
What does Boyle’s law state?
Volume of a gas is inversely proportional to pressure at constant temperature
what’s Avogadro’s law?
Volume of a gas is proportional to the # of moles at constant temp and pressure
What conditions do you need to get a real gas to act more like an ideal gas?
Gases under lower pressure and higher temperatures behave more ideally than gases with higher pressures and lower temps
According to the kinetic molecular theory, the kinetic energy of a gas molecule (increases/decreases) proportionally with temp?
increases
are ionic solids electrically conductive?
No,
but they can conduct if they are in aqueous solution or if they are molten
What unit of measurement is derived from Newton per square meter. (kg/m*s^2)
[wikipedia]
pascal
what is the short form (symbol/abbreviation) for the pascal?
Pa
how many pascals is equal to 1 atm?
101,325 Pa or
101.325 kPa
how many mmHg do you need to equal 1 atm?
760 mmHg
what is another unit that equals mmHg, so that every numerical value for mmHg is equal in the other unit?
torr
Do alkaline earth metals generally have high or low electron affinities?
low
what scale is used to measure electronegativity?
Pauling scale
what element is the least electronegative?
Cesium
what is the highest electronegativity value?
4.0, (some sources say 4.1)
the characteristic of electronegativity is related to what other periodic trend/characteristic?
ionization energy
metals generally have [high/low] melting points
high
transition metals have [high/low] melting points and [high/low] boiling points
high melting,
high boiling
how hard/soft are transition metals?
very hard
ionic compounds have [high/low] melting points and [high/low] boiling points.
high
high
What is the number of protons and neutrons in an element called?
Mass number
what is the most common carbon isotope?
carbon-12
what is ‘atomic mass’?
mass of an atom compared to mass of carbon-12 atom
what percentage of all carbon found in nature is carbon-12?
99
When describing the properties of an element, what does the symbol Z represent?
Atomic number
what is the unit for atomic weight?
g/mol
what is another name for a dalton?
amu
What does the abbreviation ‘u’ represent?
It’s the same thing as ‘amu’ (dalton)
what does molar mass mean?
It’s another name/term for atomic weight.
What is the term for the number of atoms in a 12-gram sample of carbon-12?
Mole
fill out this conversion:
________ amu = 1 gram
6.02 x 1023 amu = 1 g
what is each horizontal row in a periodic table called?
Period
what is the term used to describe a metal as being easily stretchable?
ductile
what is the term used to describe a metal as being easily hammered into thin sheets?
Malleable
What are halogens?
group 17 elements
What does the mnemonic I Brought Clothes From Old Navy Home refer to?
The elements that appear as diatomic molecules in their pure element form
What’s another name/term for Group 16 elements, which includes oxygen?
chalcogens
which of the noble gases are solid at room temp?
none
What is the use of Coulomb’s law in chemistry?
You use it to find the force exerted by a nucleus on the outermost electron
What is the symbol for effective nuclear charge?
Zeff
What is ionization energy?
the name given to the energy required to detach an electron from an atom in the gaseous state
with increasing Zeff, it becomes [easier/tougher] to knock off an electron (i.e., ionize).
tougher
The tendency of an atom to attract an electron and thereby form a bond with another atom is called ______.
electronegativity
What is the Pauling scale?
The most commonly used measurement of electronegativity
Which element(s) have undefined electronegativity?
noble gases
What prefix denotes 10-15?
femto-
What prefix denotes 10-9?
nano-
What prefix denotes trillionTH?
pico-
What prefix denotes tenth?
deci-
What prefix denotes 103??
kilo-
What symbol represents resonance structures when you see that symbol in a reaction equation?
∩
are all the electrons of a solid metal floating around?
NO.
only valence shell electrons
what kind of crystal is unlike metal solids (‘metal crystals’) , ionic solids, and network covalent crystals/solids?
Molecular crystals
what bond holds together ionic crystals?
Ionic bond
what bond holds together a solid piece of metal?
Metallic ‘bond’
what bond holds together a covalent network solid?
covalent
what bond holds together molecular crystals?
Van der Waals forces
what is the azimuthal quantum number?
Number assigned to each subshell/sublevel of electrons surrounding an atom
what is a ‘principal quantum number’?
the number assigned to each main ‘level’ or ‘shell’ of electrons surrounding an atom
what is each sublevel broken up into?
orbitals
what is the definition of ‘orbital’?
An area within an atom where electrons can probably be found
what is the term/name for the # assigned to each orbital?
Magnetic quantum number
what is the symbol for magnetic quantum number?
mℓ
How many orbitals does the s-sublevel have?
1
how many orbitals does the p-sublevel have?
3
what is the electron spin quantum number?
Number assigned to each electron in an atom
what scientific rule/law says that no 2 electrons in a given atom can have the same 4 quantum numbers?
Pauli exclusion principle
identify this quantum number:
-1/2
electron spin quantum number
identify this quantum number:
-2
magnetic quantum number
according to the Heisenberg uncertainty principle, what two characteristics of a particle cannot be known simultaneously?
Position, and momentum
what is the value of Planck’s constant?
6.63 x 10-34 J*s
what is the symbol for planck’s constant?
h
what is the name of the rule that states that when building up an atom’s electron configuration, electrons are placed in orbitals, subshells, and shells in order of increasing energy?
Aufbau principle
what formula do you use to find the energy of a single photon?
(p 19, EK gen chem)
E = hf
what is noteworthy about the atomic masses listed on the Periodic Table for each element?
The atomic mass/weight listed for each element is actually a WEIGHTED AVERAGE of the masses of the isotopes that are found in nature
what does the formula 2n2 tell you?
The maximum number of electrons that can be found in energy level ‘n’
what are the “main group elements”?
the elements that are not transition metals.
Main group elements are found in group 1, 2, 13-18
what is the term for the Distance traveled by a gas molecule between collisions?
Mean free path
All gases will have the same ________, if they have the same temperature, pressure, and # of molecules
volume
what is the universal gas constant? Give # and units:
0.08206 L*atm*K-1*mol-1
or
8.314 J*K-1*mol-1
what is PV = nRT? What is this equation named?
ideal gas law
what is the pascal? Define it.
An SI-derived unit of pressure/stress.
It is a measure of force per unit area.
what are the units for the pascal?
The units are Newton per square meter.
(kg/m*s^2)
what is another unit that equals torr, so that every numerical value for torr is equal in the other unit?
mmHG
What is the law/rule that electrons will not fill any orbital in the same subshell until all orbitals in that subshell contain at least one electron, AND the unpaired electrons in the subshell have parallel spins?
Hund’s rule
What does ‘standard conditions’ mean?
For laboratory/chemistry purposes, it means
~ 1 atm, and
25 degrees Celsius (= 298 K) and
1.00 molar concentration for all soluble compounds
[Kaplan, and back of barron’s ap chem. book]
what is another way of saying ‘standard conditions’?
standard state
What is the name of the model of the atom that consists of electrons in circular orbits around the nucleus?
Bohr model
Do halogens generally have high or low electron affinities?
high
What does the Pauling scale measure?
Electronegativity
Name the metalloids.
Boron,
silicon,
germanium,
arsenic,
antimony, and
tellurium
(suhail’s Kaplan p 27)
How many valence electrons do the halogen elements have?
7
network crystals are AKA?
network covalent crystals
AKA
covalent network solids
____ compounds do Not contain molecules.
All of the following are correct:
–Ionic
–Network covalent
–Metallic
What formula gives the total Kinetic Energy of n moles of gas?
(3/2)*nRT
How is the speed of a gas related to its temperature?
The speed of a gas is proportional to the square root of its temperature.
How does the weight of a gas molecule relate to its speed?
the Velocity of a gas is inversely proportional to the square root of it’s Atomic mass.
The universal gas constant (R) is a product of these 2 constants:
Boltzmann’s constant, and
Avogadro’s number
Given a rate law for a reaction,
(e.g., Rate = k [A]2 [B]4)
what is the Order of the reaction?
Add the exponents.
2 + 4 = 6
T/F:
The rate constant (k) of a reaction depends on the concentration of the reactants.
Fals
T/F:
The rate constant (k) of a reaction depends on the Temperature.
tru
T/F:
A catalyst does not alter the rate law of a reaction.
fals
T/F:
A catalyst alters the rate constant (k) of a reaction.
tru
Rate = k [A]2 [B]4
What is the above called? What is it an example of?
it’s a rate law
Name the equation that mathematically expresses the rate constant of a reaction.
Arrhenius equation
T/F:
Equilibrium constant is the same thing as rate constant.
FALS.
Equilibrium constant is Keq found in mass-action expressions.
Rate constant is the k found in rate laws.
What is the relationship between temperature and Keq?
The Keq for a given reaction is constant at a given specific temperature.
A negative Keq value tells you that the reaction favors:
reactants
A positive Keq value tells you that the reaction favors:
products
If a Keq value is 1, then the reaction favors:
the reaction balances products and reactants. So neither side is “favored”
How is the Rate law of a reaction related to it’s equilibrium and Keq?
Rate law, and Keq are not related.
(1) What is Q?
(2) How does Q relate to Keq?
(1) Q is the ratio of products to reactants (with each one raised to an exponent = to it’s coefficient in the reaction equation). To put it more simply:
(2) Q is simply the Keq when the reaction is **not at equilibrium. **When the Q = Keq, then the reaction is at Equilibrium.
What does it mean, if Q is less than Keq?
reaction proceeds forward
What does it mean, if Q is more than Keq?
Reaction proceeds in the reverse direction.
T/F:
Changing the volume of a reaction container will affect the equilibrium.
Partially true.
This is true ONLY for reactions involving gases.
T/F:
Adding an inert (noble) gas to a reaction container will change the equilibrium, since it affects the volume.
Fals.
Inert gases do not react. And the volume (of the container) is not changed.
Thus, equilibrium is unaffected.
A [#]-order chemical reaction follows the same trend as a half-life reaction.
FIRST
The half-life of a [#]-order chemical reaction is INdependent of the starting concentration of the reactant.
FIRST
The half-life of a first-order chemical reaction is [dependent / INdependent] of the starting concentration of the reactant.
independent
T/F:
A first-order (elementary) reaction is unimolecular.
tru
A first-order (elementary) reaction is [unimolecular / bimolecular].
uni
A second-order (elementary) reaction is [unimolecular / bimolecular].
bi
T/F:
A second-order (elementary) reaction is unimolecular.
fals.
second-order is bimolecular.
When the concentration of reactants are doubled, the rate of a first-order (elementary) reaction is [unchanged / halved / doubled / quadrupled].
doubled
When the concentration of reactants are doubled, the rate of a second-order (elementary) reaction is [unchanged / halved / doubled / quadrupled].
quadrupled
What’s the difference between an intermediate versus an activated complex?
An intermediate is formed during a multi-step reaction, where it is the product of one of the steps and will become a reactant in another of the steps.
An activated complex is formed the middle of a (single step) reaction when the reaction’s energy is near it’s Ea (“activation energy”).
In an isolated system, what can be exchanged between the system and its surroundings?
Nothing!
neither matter, nor energy
In an closed system, what can be exchanged between the system and its surroundings?
ONLY energy
If a person pushes down on a piston, the gas inside the leak-free tube is compressed.
This is an example of a/n [open / closed / isolated] system.
closed
What is convection?
transfer of heat energy thru a fluid (liquid, gas)
The 2 very best insulators are:
vacuum
and
air
What are state functions?
a measurable property, of a system, that depends only on the current state of the system, not on the way in which the system acquired that state (i.e., independent of time, history, or path)
Which of these properties of a gas is/are state functions?
- temperature
- heat
- work
temperature only
What is a black body radiator?
an idealized physical body that absorbs ALL incoming EMR
A black body can radiate/emit EMR if:
if the black body is at thermal equilibrium (i.e., at constant temperature)
Nothing can be exchanged between a/n **[open / closed / isolated] **system and its surroundings.
isolated
What is the FIRST Law of Thermodynamics?
The 1st law of conservation of energy states that the **total energy **of an isolated system is constant; energy can be transformed from one form to another, but cannot be created or destroyed.
What is the SECOND Law of Thermodynamics?
the entropy of an isolated system never decreases.
- Another way of saying it: *Isolated systems move towards maximum entropy.
- Another way of saying it:* If no energy enters or leaves a system, then the potential energy of the state will always be less than that of the initial state. AKA, entropy happens.
What is the THIRD law of Thermodynamics?
It’s impossible for any process, no matter how idealized, to reduce the entropy of a system to absolute-zero
The 3rd Law of Thermodynamics is AKA:
Nernst’s theorem, or
Nernst’s postulate
What is the mathematical expression for enthalpy?
enthalpy = U + P*V
where:
U = internal energy
P = pressure
V = volume
What does the superscript º indicate, in : Δ Hfº
All reactants and products are at 1 atm
What is the entropy of a substance at Zero degrees Kelvin?
zero entropy
q / T = ????
Δ S = heat / Temperature
(Δ S means “change in entropy”)
Δ G is spontaneous only if _______ remain(s) constant.
Pressure
&
Temperature
T/F:
A spontaneous rxn cannot be endothermic.
Fals
Under a spontaneous rxn, the free energy (Δ G) of the universe [increases / decreases].
↓↓↓
For a rxn to be spontaneous, the entropy of the Universe must:
↑↑↑
increase
A reaction is spontaneous at all temperatures. This reaction is [endothermic / exothermic] and [increases / decreases] the entropy of the system.
exo-
and
↑↑↑
What effect do catalysts have on the spontaneity of the reaction?
no effect
If a reaction is at equilibrium, then that reaction’s Δ G is [ positive / negative / zero ].
zero
What’s a mole fraction?
the amount of a constituent (expressed in moles), divided by the total amount of all constituents, in a mixture
For ideally dilute solutions, the mole fraction of the solvent is:
close to 1
Ideal solutions obey _____ Law.
Raoult’s Law
A collistion between 2 objects is elastic, if:
the Kinetic Energy before the collision, is the same as the K.E. after the collision.
A ______ collision between 2 objects has a different final Kinetic Energy than the initial K.E. of the objects.
inelastic
Can dialysis extract colloidal particles?
Yep
Can simple filtration extract colloidal particles?
Nope
What is the Tyndall Effect?
When a beam of light passing through a colloid is dispersed, so that the beam becomes visible from the side (i.e., viewed perpendicular to path of beam).
What’s the observed difference between light passing through a colloidal suspension, versus through a true solution?
Light passing through a true solution is not dispersed, so it cannot be seen from the sides.
Light passing through a colloidal suspension can be seen from the sides.
(1) Can a colloid be extracted from suspension by addition of electrolyte?
(2) Why, or why Not?
Adding heat, or electrolytes, causes colloid particles to bind together, allowing them to be pulled down by gravity.
T/F:
If a compound/molecule is very soluble in H20, then it must be a strong electrolyte.
Fals.
Vinegar, for example, is a weak electrolyte but is very soluble in water.
Define mole fraction.
Mole fraction of a solution is:
of mol of solute, divided by # of mol of solution.
Define parts per million.
grams of solute / grams of solution
Define heat of hydration.
Enthalpy change when gaseous solute is dissolved in liquid.
A solid sublimates when the _____ of that solid is greater than the ______.
vapor pressure;
the partial pressure of the vapors above that solid.
Evaporation and Boiling are different. Evaporation occurs when the _____ of the liquid is greater than the ____.
vapor pressure;
partial pressure of the vapors already above the liquid.
Boiling occurs when the ______ of the liquid is greater than the _______.
vapor pressure;
total pressure of the gas above it.
An object’s vapor pressure decreases if _______ also decreases.
temperature.
Condensation of a (gaseous) substance occurs when the _____ is greater than, or equal to, ______.
partial pressure of that substance’s gas particles is greater than or equal to the vapor pressure.
List the colligative properties of solutions:
- vapor pressure
- boiling point
- melting point
- osmotic pressure
According to Raoult’s law, actual vapor pressure is the product of:
actual vapor pressure of solvent = (Vapor pressure of pure solvent) * (mole fraction of solvent)
Define “steam”.
Water vapor above 100 degrees Celcius
A non-volatile solute is a solute that ______.
has No vapor pressure.
As atmospheric pressure ↑↑, vapor pressure [increases / decreases / is Not changed].
does Not change
Which Groups on the periodic table are readily soluble in Water?
Halogens,
Alkali metals
Is ammonia soluble in Water?
Yep
Does the solubility product (Ksp) of a compound change, if the pH of the solution changes?
Nop. Ksp** only changes with **Temperature.
What is the trick to guesstimate the solubility of a compound, using that compound’s solubility product (Ksp)?
Guesstimating SOLUBILITY:
IF the compound dissociates into 2 particles, solubility is ≈ the SQUARE ROOT of the compound’s Ksp.
IF a compound dissociates into 3 particles, then the solubility ≈ the CUBE ROOT of the Ksp.
TRICK:
Divide the exponent on the Ksp by 2 for the two-particle compounds;
Divide the exponent on the Ksp by 3 for three-particle compounds.
When you write the Ksp for a given dissolved substance, what part of the sol’n is not included in the Ksp “expression”?
( “expression” → Ksp = []*[] )
Pure liquids; and
pure solids
What is a “saturated sol’n”?
2 definitions:
- sol’n that is in equilibrium w/ its precipitate
- sol’n whose ion-product (i.e., []*[] ) is equal to Ksp
If Metal A and a different Metal B are given the same amount of heat, but Metal A’s Temperature rises more quickly:
Which metal has the higher specific heat?
Metal B
In the formula q = mCΔT, “c” stands for:
the specific heat of a given substance
What is the specific heat of H2O?
1 cal / (g * ºC)
or
1 cal / (g * K)
or
1 J / (mol * K)
T/F:
The heat capacity of an object increases with its size.
tru
The energy transfer (“q”) is rougly = ΔH if there is:
constant pressure
(like in a coffe-cup calorimeter)
- Bomb calorimeters measure ______.
- Coffee cup calorimeters measure ______.
Energy
Enthalpy
In a coffee-cup calorimeter, _____ is held constant.
pressure
What is the Heat of Fusion of Water? (give the numerical value)
80 cal/g
What is the difference between the phase diagram for the H2O versus the phase diagram for most other solutions?
In the phase diagram of Water, the solid-liquid boundary line has a NEGATIVE slope.
(which is why ice skating is possible - see PR Hyperlearning Review p. 377)
On a phase diagram, what is the critical point?
The temperature and pressure, beyond which a substance will become a supercritical fluid.
What’s a supercritical fluid?
a substance that displays the properties of both a gas and a liquid.
What is the “heat of formation”?
the amount of energy required to make one mole of a compound from pure elements in their natural or standard state.
When talking about a phase diagram, what is the critical temperature?
the Temperature, above which no liquid will form, regardless of how high the pressure is
What are the labels for the axes (x-axis and y-axis) of a phase diagram?
Y-axis: Pressure
X-axis: Temperature
Is supercritical fluid the same thing as plasma?
no
Henry’s Law is about:
the solubility of gases in liquids
What is the equation for Raoult’s Law?
actual vapor pressure of a solvent =
(vapor pressure of solvent when it’s unadulterated and all by itself) * (mole fraction of solvent in sol’n)
Define vapor pressure.
the pressure exerted, by the gaseous particles of a liquid which evaporated from the exposed surface of the liquid, on the liquid
When talking about liquids, what is a volatile liquid?
Liquids which easily vaporize, and thus have a high vapor pressure
What is the formula/equation for calculating osmotic pressure?
π = iMRT
- What is the SYMBOL for osmotic pressure?
- What is the UNIT for osmotic pressure?
- π
- atm (atmospheres)
In a copper-zinc galvanic cell, electrons flow from the Anode in the _____ sulface solution, to the Cathode in the _____ sulfate solution.
- zinc
- copper
Cations in the salt bridge of a galvanic cell move from the negatively charged _____ side to the positively charged _____ side.
- cathode
- anode
The emf of a galvanic cell depends on all the following:
- temperature of the solution
- concentration of the solution
- reactions in the solution
In a galvanic cell, reduction occurs at the [anode / cathode].
cathode
How soluble, in water, are salts of sodium?
All Na salts are soluble in water
How soluble, in water, are nitrates?
all nitrates are water-soluble
All compounds which contain these (monoatomic and polyatomic) ions, are water-soluble:
Li+,
Na+,
K+,
NO3_,
C2H3O2_,
ClO3_,
ClO4_
Are compounds containing halide anions, soluble or insoluble?
Compounds containing Cl-, Br-, and I- are soluble, except when these ions pair with Ag+, Hg22+, or Pb2+
Compounds containing Cl-, Br-, and I- are soluble, except when these ions pair with [these ions].
Compounds containing Cl-, Br-, and I- are soluble, except when these ions pair with Ag+, Hg22+, or Pb2+
Which compound(s) are regarded as slightly soluble, rather than insoluble or soluble?
- calcium* hydroxide,
- barium* hydroxide,
- strontium* hydroxide
Compounds containing the sulfate anion are [soluble/insoluble/slightly soluble].
Soluble, except
when sulfate bonds to Sr, Ba, Pb, Ag, or Ca.
Compounds containing the **hydroxide **anion are [soluble/insoluble/slightly soluble].
Insoluble, except
when bonded to Li, Na, K, NH4+.
*** When bonded to these cations, the hydroxide-containing compounds become slightly soluble: Ca, Sr, or Ba.
Are compounds containing the S2- anion soluble, insoluble, or slightly soluble?
Sulfides are insoluble, except
when containing Li, Na, K, NH4+, Ca, Sr, or Ba.
Compounds containing the carbonate anion are [soluble/insoluble/slightly soluble].
insoluble, except
when bonded to Li, Na, K, or NH4.
Compounds containing the phosphate anion are [soluble/insoluble/slightly soluble].
insoluble, except
when bonded to Li, Na, K, or NH4.
In a galvanic cell, oxidation occurs at the [anode / cathode].
anode
T/F:
A catalyst can ↑↑ the total amount of a product that is produced
fals.
Catalyst can ↑↑ the RATE of a rxn; it cannot change the final amount of product that is made
What is the azimuthal quantum number (ℓ) for the s sublevel?
0
What is another name/term for azimuthal quantum number (ℓ) ?
angular momentum quantum number
Decreasing the diameter of the metal wire used in a circuit, will [increase / decrease] the resistance.
↑↑
What is specific gravity?
density of something ÷** density of **water
Formula for Buoyant Force =
= (density of fluid) * (g) * (Volume that is submerged in water)
= [(density of water) ÷ (density of object)] * weight
