General Chemistry Flashcards
What is going from solid to liquid phase?
melting (Fusion)
Liquid to a gas is called?
Vaporization (boiling)
What is it to go from gas to liquid?
condensation
What is it to go from solid to gas?
sublimation
What is it to go from gas to solid?
Deposition
What is the triple point?
Where all three phases are existing at the same pressure and temperature
What is the critical point?
Point where you cannot tell the difference between liquid and gas
On a phase diagram, which way would be endothermic?
Back to the previous phase
ie. gas to solid = sublimation
is endothermic
How do you calculate the formal charge?
Formal charge = (valence e-) - (Sticks + Dots)
Ideal formal charge = 0
Explain Resonance Structures
In molecules with open p orbitals, electrons can be delocalized or shared among atoms in more than one way, creating extra stabilization
What are the structures for NO3-, NO2+, NO+, NH2OH
List them in order from strong to weak bond strength
NO+ > NO2+ > NO3- > NH2OH
NO3- sometimes has single bonds and sometimes double bonds
What is the geometry arrangement, Shape, angle and an example of something with:
2 Electron Pairs
0 Nonbonding Pairs
Example: BeCl2
Shape: Linear
Angle: 180 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
3 Electron Pairs
0 Nonbonding Pairs
Example: BH3
Shape: Trigonal Planar
Angle: 120 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
4 Electron Pairs
0 Nonbonding Pairs
Example: CH4
Shape: Tetrahedral
Angle: 109.5 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
4 Electron Pairs
1 Nonbonding Pairs
Example: NH3
Shape: Trigonal Pyramidal
Angle: 107.5 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
4 Electron Pairs
2 Nonbonding Pairs
Example: H2O
Shape: Bent
Angle: 104.5 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
5 Electron Pairs
0 Nonbonding Pairs
Example: PCl5
Shape: Trigonal Bipyramidal
Angle: 180, 120, 90 Deg
What is the geometry arrangement, Shape, angle and an example of something with:
6 Electron Pairs
0 Nonbonding Pairs
Example: SF6
Shape: Octahedral
Angle: 180, 90 Deg
What are the types of intermolecular forces, list in decreasing strength
Result of electrostatic interactions between charges or partial charges on different molecules
- Ion-dipole
- Hydrogen
- Dipole-Dipole
- Dipole-Induced dipole (Debye)
- Induced dipoles only (LDF)
What does the principle number (n) tell you?
The rows on the periodic table
Higher energy level= larger radius
What does the angular (l) tell you?
Specifies the subshell within the principal energy level value can be any integer from 0 to (n-1)
0=s , 1=p , 2=d , 3=f
What does the magnetic (ml) tell you?
Specifies the orbital within the subshell
Possible values range from -L to L
eg. p orbital has ml values of -1, 0, 1
What does the spin (ms) tell you?
Can be either -1/2 or 1/2 and denotes inherent spin
Electrons in the same orbital must have opposit spin signs
What is Hund’s Rule?
Electrons fill into a subshell such that there are a maximum number of half-filled, parallel spin orbitals
(like a movie theater where you leave a space open between people that are not known)
What is Aufbau’s Principle?
Electrons fill accoruding to the (n+L) rule such that the subshell that has the smallest sum with the smallest n fills first
Explain the isotope notation
A = Atomic weight (mass) = Protons + Neutrons
Z = Atomic Number = # of protons
( ) = Charge (if present)
How is the periodic table arranged?
By number of protons
What are Alkali metals?
First column on the periodic table
Form +1 cations; highly reactive
(e.g. Na)
What are alkali earth metals?
Second column on the periodic table
Form +2 cations; Somewhat
(e.g. Ca)
What is the Carbon Family?
IVA group with 4 valence e-
Not easily ionizable; mix of properties
(e.g. Si)
What is the Nitrogen Family?
VA group with 5 valence e-
Not easily ionizable; mix of properties
(e.g. P)
What is the Oxygen Family?
VIA group with 6 valence e-
Form -2 anions; somewhat reactive
(e.g. F)
What are Halgens?
VIIA group with 7 valence e-
Form -1 anions; highly reactive
(e.g. F)
What are Noble Gases?
VIII A Group
Do not form ions or react
(e.g. Ne)
Describe the metals group on the periodic table
Group I and II especially. Form cations. Ductile, malleable, shiny, conductive
Describe the Transition metal group on the periodic table
d-block. may be able to form multiple cations and are colored when in ionic form. Particularly hard metals with high melting and boiling points
What are nonmetals on the periodic table?
Groups VI, VII and VIII especially form anions.
Brittle, poor conductors
What are Metalloids/ Semimetals on the periodic Table?
Lower left p-block also known as staircase.
Mixed properties, so specific characteristics are rarely tested
What is the effective Nuclear Charge (Zeff) and what is the trend on the periodic table?
The net positive charge a valence electron feels from the nucleus
- More positive nucleus: Higher Zeff
- More e- shielding: lower Zeff
What is the atomic radius and what is the trend?
Size of the atom
(only one opposit of Zeff)
Increase Zeff = Decrease r
What is electronegativity and what is the periodic trend?
Degree of attraction an atom has for electrons in a chemical bond
Increase Zeff = Increase E-
What is Ionization Energy and what is the periodic trend?
Energy required to completely remove an electron from an atom
What is electron affinity and what is the periodic trend?
Energy released when an electron gets an atom
Increased Zeff = Increased EA
What is the difference between a compound and a molecule?
- Molecules are two or more atoms held together. (eg H2)
- Compounds require those elements to be different. (eg H20)
What is the difference between Molecular Mass vs. Molar Mass?
- Molecular mass is the weight of one molecule in Daltons (Da or u)
- Molar mass is the weight of one mole of molecules in grams
- 1 mole = 6 x 10^23 entities
- 1 mole x 1 u = 1 gram
What is the difference between Empirical and Molecular Formulas?
- Empirical formulas use the smallest whole number ratio of atoms (eg. CH2O)
- Molecular formulas use the actual number of atoms (eg. C6H12O6)
How do you calculate the percent composition?
Percentage of mass contributed by each element in a compound
% composition = (Mass of X in formula) / (Formula weight of compound)
Describe the steps for balancing a reaction
See attached
What are limiting reactants?
The reactant completely consumed first, halting the forward reaction
What is the Stoichiometric Ratio?
Optimum ratios of moles of reactants such that all reactants are consumed.
Calculate ratios by dividing moles available by coefficients in balanced reactions
What is the theoretical yield?
The maximum yield calculated
What is the actual yield?
The experimental yield actually measured
How do you calculate the percent yield?
% Yield = (Actual Yield) / (Theoretical Yield) x 100
What is Enthalpy?
Delta H
The total heat content (energy) of a system
Describe an exothermic reaction
Heat given off
Lower potential energy in the products
Negative (-) Delta H
Describe an exothermic reaction
Heat taken in
Higher Potential Energy in products
Positive (+) delta H
What is the equation for the transfer of heat?
Delta U = Q - Wby system
Where:
Delta U = Change in internal energy
Q = Heat transferred
W = Work done by the system
Often seen as:
Wby = -Won
Name and describe the way that heat can be transfered
- Radiation = transfer of heat by eectromagnetic waves
- Conduction = Transfer of heat through direct contact
- Convection = Transfer of heat through bulk motion
What is the standard heat of fusion?
Delta H for the formation of 1 mole of substance
delta H = (sum of delta H products) - (sum of Delta H reactants)
Explain Hess’s Law
If a reaction can be broken down into a series of steps, the enthalpy change for the overall net reaction is the sum of the enthalpies of each step
Which bond is going to be more difficult to break:
N-H or O-H bond? Why?
O-H bond because it is it is more electronegative
What is entropy?
The disorder of a system; the energy of a system unable to do work
Gasses have the highest entropy
(Delta s)
Explain Gibbs Free energy. State the equation and explain results
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = - and dS = +
spontaneous or nonspontaneous?
Spontaneous = dG is negative
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = + and dS = -
spontaneous or nonspontaneous?
nonspontaneous
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = - and dS = - with low temperature
spontaneous or nonspontaneous?
spontaneous
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
dH = + and dS = + with low temperature
spontaneous or nonspontaneous?
spontaneous
The energy of a system to do work
dG = dH - T*dS
If
dG < 0 Spontaneous (Forward; more products)
dG = 0 Equilibrium (same concentration)
dG > 0 Nonspontaneous (Reverse; more reactants)
If frozen ice melts into liquid water, what sign is enthalpy and entropy?
Endothermic (heat input)
Enthalpy = Increases
Entropy = Increases
What is molecular equilibrium and how is it calculated?
Reaction Quotient (Q)
For a Reaction
aA + bB = cC + dD
Q = [products] / [reactants]
=( [C]c * [D]d ) / ( [A]a * [B]b ) = Keq
What is the equilibrium constant and compare it to Q?
Keq
Q < Keq Not yet reached equilibrium; rxn proceeds forward
Q = Keq at equilibrium; rate forward = rate reverse
Q > Keq Overshoot equilibrium; rxn proceeds in reverse
What is Le Chatelier’s Principle
If a stress (a change in concentration, pressure, or temperature) is applied to a system at equilibrium, the system will shift in such a way as to relieve the applied stress
If temperature increase is in the products, what does this mean?
Products = exothermic reaction
Reactants = Endothermic reaction
If pressure is increased,
what moles will be favoried (gas)?
what volume is favored?
Increased pressure means:
low moles favored (gas)
low volume favored
If pressure is decreased,
What moles and volume favored?
Pressure decreased favored
increased moles (gas)
increased volume
What is the Ion Product (Qsp) and how does it compare to Ksp
Q for Solutions
For example: NaCl
IP = [Na+] [Cl-] = Ksp
- Solubility product constant (Ksp)
Keq for solutions
Qsp < Ksp Unsaturated
Qsp = Ksp Saturated
Qsp > Ksp Supersaturated
What is the molar solubility
The concentration at saturation (X)
molarity = mol/liter
this is the moles at 1 liter
For example: if you have NaCl ,
Ksp = [Na+] [Cl-]
Therefore, molar solubility is represented as (x) in:
Ksp = [x] [x] = x2
What is the common ion effect?
If the same ion is already in solution its concentration must be added to the concentration
Example:
NaCl = Ksp = 3.8 x 10 (higher = want to dissociate)
AgCl = Ksp = 1.6 x 10^-10 (will percipitate out)
This (AgCl) will percipitate out due to the excess Cl in solution and AgCl has the lower Ksp so it will be the one to percipitate
What is Kaplan Method for Equilibrium Questions
(Using NaCl for this example)
- Write down a balanced reaction for the dissociation reaction (if not given)
NaCl (s) -> Na+(aq) + Cl-(aq)
- Find the expression for the Keq
Ksp = [Na+] [Cl-]
- Plug into Ksp expression
Ksp = [x] [x] = x2
(x = molar solubility)
What is the rate law based off of?
Concentration of the REACTANTS!
ie. For a reaction aA+bB -> cC + dD
Rate = k [A]x [B]y
k = rate constant
x + y = order of reaction
How do you calculate the order of reaction?
Concentration of the REACTANTS!
ie. For a reaction aA+bB -> cC + dD
Rate = k [A]x [B]y
k = rate constant
x + y = order of reaction
What are the reaction orders?
-
Zero order: rate = k
- [reactant] does not affect rate
- eg. doubling concentration (x2) has noeffect on rate (x20)
-
First order: rate = k[A] or rate=k[B]
- [reactant] affects rate linearly, x:x
- eg. doubling concentration (x2) doubles
- Second order: rate = k[A]2 , rate = k[B]2 , rate = k [A]1[B]1
Name and describe the factors affecting rate
-
Reaction concentration
- Increasing [M] generally increases rate, up to a maximum
-
Temperature
- Increasing temperature generally increases rate, to a max
-
Medium
- Some reactions perform better in certain medium (eg. Polar vs. nonpolar)
- Usually impacts the reaction mechanism
-
Catalysts
- (such as enzymes) increase rate by decreasing activation energy
Explain the phase change diagram, where is delta Hfus and where is delta Hvap?
delta Hfus = ice to liquid phase change
delta Hvap = liquid to vapor phase change
How is the heat put in (q) calculated when the phase is changing from either solid to liquid or liquid to gas?
q = m*delta Hfus (in joules)
q = m*delta Hvap (in joules)
How is the heat put in calculated when going from one temperature to another in either the solid, liquid or gas phase?
q = m*c*delta T
What is the specific heat of liquid water?
c = 1 cal/g*degC
What is the specific heat?
(c) heat required to raise the temperature of one unit mass of a material by 1 deg C
eg. cwater = 1 cal/g*deg C
What is heat capacity?
(m*c) heat required to raise the temperature of a particular mass
What makes up the calculation for determining the heat into a system? (include units)
q = m*c*delta T
q = heat in J
m = mass in g
c = specific heat in cal/g*deg C
T = temperature in deg C
What is the heat of fusion?
Energy required to change one unit mass from solid to liquid
What is the heat of vaporization
Energy required to change one unit mass from liquid to gas
What is vapor pressure?
Pressure at the surface of a liquid, proportional to temperature
When does water boil?
Pvapor = Patmosphere
If you are in Denver, vs. sea level, what temperature does the water be to boil
Sea level boiling temp = 100 deg C
Denver boiling temp = 98 deg C
Because of this, the pasta in Denver would have to cook longer than pasta at sea level because of the boiling temperature difference
How many gases on test day will be Ideal gas?
ALL OF THEM!
unless otherwise stated..
Explain the Kinetic Molecular Theory of Gases (Ideal Gas)
- Particules have negligible volume
- There are no intermolecular attraction or repulsion
- Molecules are in continuous, random motion
- Collisions are elastic. conservation of DE is observed
- The average Kinetic Energy of gas particles is proportional to the absolute temperature
What is temperature and what units do we use for these gas calculations?
- Measure of average Kinetic Energy (KE)
- SI unit is Kelvin
Calculated by:
degC + 273 = Kelvin
What is Pressure and what unit is used for the gas calculations?
- Measure of force/area
- SI unit is pascals (Pa)
What is the conversion between atm, Pa, torr, and mmHg?
1 atm = 105 Pa = 760 torr = 760 mmHg
What is mole fraction?
How is the mole fraction of O2 calculated if you have 2 moles CO2, 10 moles of He and 8 moles of O2
- Mole fraction = x
XA = (Moles of A) / (Total moles of compound)
XO2 =(8 moles O2) / (20 total moles) = 0.4
What is Dalton’s Law of Partial Pressure?
For example, if you had an XA = 0.4 and a total pressure of 40, what would the partial pressure of A be (PA)?
In a mixture of gases, total pressure equals the sum of the pressures from each individual gas
Ptotal = PA + PB + PC + …….
PA = XA * Ptotal
PA = 0.4 * 40 = 16
What is Boyle’s Law?
At constant temperature, the volume of a gas is inversely proportional to its pressure
P1V1 = P<span>2</span>V<span>2</span>
**Inversly proportional (hyperbolic curve)
Remember this by, boyle on body has a specific pressure and volume
What is the ideal gas law equation?
PV = nRT
What is Charle’s Law?
At constant pressure, a gas’s volume is directly proportional to its temperature
V1/T1 = V2/T2
Directly proportional = straight Line
How to remember:
Charlie sheen is on TV!!!
What is Avogadro’s Law?
The volume of gas is directly proportional to the number of moles of the gas (n)
V1/n1 = V2/n2
Directly proportional = straight line
What is the standard temperature, pressure and volume?
Temperature = 273 Kelvin
Pressure = 1 atm. 760 torr, 760 mmHg, 105 Pa
Volume = 22.4 L/mol
What is the solute?
The substance being dissolved (the compound in smaller quantity)
What is the solvent?
The dissolving medium (the compound in greater quantity)
What is Molarity?
M
Concentration
M = moles of solute / kg of solvent
used to calculate in dilutions
What is Molality?
m
m = Moles of solute / kg of solvent
used for coligulative property calculations
How are dilutions calculated?
M1V1 = M2V2
M = molarity mol/L
V = volume of molarity in L
Explain what colligative properties are
Physical properties of solutions that depend only on solute concentration
Explain the Vapor-pressure depression Calligative property
delta Psoln = Xsolute * Posolvent
More solute means less of the liquid’s surface area is available for evaporation
For example, if you add oil to pasta, less water is available on the surface to vaporize meaning it will take more time to boil the pot of water
Explain boiling-point elevation colligative property
delta Tb = i*Kb*m
Kb = unique solvent constant deg C*kg/mol
i = van hoft factor (# of new particles per mole solute, ie. NaCl has an i = 2)
m = molality is mol/kg
delta Tb = increases in boiling point in K
Boiling occurs when Pvap = Pambient
Lowering Pvap by adding solute, thus raises Boiling Point
For example, if you add salt (lots) to a pan of water, it will boiler quicker
Explain freezing-point depression colligative property
delta Tf = i*Kf*m
Kf = unique solvent constant deg C*kg/mol
i = van hoft factor (# of new particles per mole solute, ie. NaCl has an i = 2)
m = molality is mol/kg
delta Tf = increases in freezing point in K
Solute interrupts the ability of the solvent to form solid crystals, lowering the freezing point
What is osmotic pressure and how is it calculated?
The pressure that would need to be applied to a solution to prevent osmosis
π = iMRT
Or P = [mol/(L*V)] * RT
M= molarity mol/L
T = temperature in Kelvin
R = ideal gas constant (atm*L/mol*K)
i = Van’t Hoff factor in particles/mol
Explain factors affecting solubility trend
For water as the solvent:
As temperature increases, solubility of a solid increases
As temperature increases, solubility of a gas decreases (because making more gas)
Remember, like disolves like…
How many kg is equal to a liter of water?
1 kg = 1 L of water
Explain an Arrhenius acid/base
The Arrhenius definition for acids and bases is limited to aqueous solutions
- Acids = Proton (+H) donor ex. HCL, HNO3, H2SO4
- Bases = Hydroxide ion (OH-) donor ex. NaOH, KOH, Fe(OH)3
What is a Bronsted-Lowry acid/base?
The Bronsted-Lowry definition is what the DAT use in general
- Acids = Proton (H+) donor ex. HCL, HNO3, H2SO4 and also H20
Bases = Proton (H+) acceptor ex. NaOH, KOH, Fe(OH)3 and also NH3 (g) and H2O
What is lewis acid/base?
Lewis bases are also called Ligands (makes a complex)
Lewis acid-base reactions are complexation reactions
- Acid: an acid is an electron pair acceptor (eg. BF3)
- Base: an electron pair donor (eg. NH3 with lone pair)
Example complex is BF3NH3
Explain conjugate acids and bases
Acids and bases always have conjugate pairs
If strong acid or base, conjugate will be so weak that it is negligable
If weak acid or weak base, the conjugate will also be weak
What is an Amphoteric Species?
This is a species that can act as an acid or a base
eg. water
Explain Autoionization of water
H2O(l) <-> H+ + OH-
Kw = [H+] [OH-] = 1 x 1014
Makes sense because pH scale is 0 to 14
Explain Acid Dissociation Constant (Ka)
HA + H2O <-> A- + H3O+
Ka = [A-] [H3O+] / [HA] = [products] / [reactants]
If it is a very strong acid, how does the Ka compare?
Strong acids have very large Ka’s because the products are very large and the reactants are low
How does a very strong base compare to Kb?
Strong base have a high Kb, or very low Ka value
Explain Base Dissociation Constant Kb
B + H2O <-> HB+ + OH-
Kb = [HB+] [OH-] / [B] = [products] / [reactants]
Explain the p function for acid and bases.
p(anything) = - log (anything)
example:
pKa = -log (Ka)
pKb = -log (Kb)
pH = -log (H+)
Explain the major shortcut used for figuring out the pH of a solution, given the concentration.
For example, [H+] = 2.3 x 10-13
[anything] = m x 10-n
then p[anything] = (n-1) . (10-m)
for this example: p[H] = (13-1) . (10-2) = 12.8
Explain strength of Acids and Bases
“Strong” acids and bases totally dissociate in solution; high Ka and Kb
“Weak” acids and bases partially dissociate in solution; low Ka and Kb
What are the strong acids?
HCl
HBr
HI
HNO3
H2SO4
HClO4
NOTE: HF is a weak acid as it wants to keep those electrons with its high electronegativity
Explain the Equivalence point
VANA = VBNB
VA = Volume of Solution A (L)
N<span>A </span>= Normality of A (equivalence / Liter)
VB = Volume of Solution B (L)
NB<span> </span>= Normality of B (equivalence / Liter)
How is the Normality Calculated?
N=M X equivalence / mol
An equivalent is the number of acid or base species in solution for each solute
ex. H2SO4 has 2H+ available, so 1 mole H2SO4
= 2 N H2SO4
Explain strong acid - strong base titration
eg. HCl with NaOH
At equivalence point where [H+] = [OH-]
Explain a curve where the equivalence point is above the pH of 7
weak acid, strong base
eg. CH3COOH with KOH
What is a polyprotic acid?
An acid with two or more protons
Example: polyprotic acid - strong base titration
ex. H2SO4 with NaOH
What is the henderson hasselback equation for pH
pH = pKa + log [conjugate base / weak acid]
pOH = pKb + log [conjugate acid / weak base]
At the equivalence point, how is the henderson hasselback equation used to calculate the pH
[A-] = [HA] then
pH = pKa + log [1/1]
Recal log(1) = 0
pH = pKa
Solve the following problem
Remember, you are using normality and not molarity
What is Reduction? what is Oxidation?
OIL RIG
Reduction = is gain of electrons
Oxidation = is loss of electrons
What is a reducing agent
Becomes oxidized; reduces something else
like a travel agent, it helps you be reduced by itself being oxidized
What is an oxidizing agent?
Becomes reduced, oxidizes something else
What are the rules for calculating the oxidation number?
See attached
How do you balance a redox reaction?
See attached
What charge is an anode?
negative
Anode (-)
What charge is a cathode?
Positive (+)
(Cats are AWESOME)
What direction does electrons flow in either a Galvanic or Voltaic cell?
Anode (-) to Cathode (+)
Alphabetically
What side in a Galvanic/Voltaic cell is oxidized?
Anode = Oxidized
An ox
What side in a Galvanic/Voltaic cell is reduced?
Cathode (+) is reduced
Red Cat
What is the delta G for the Galvanic/Voltaic cell?
Delta G < 0
SPONTANEOUS
Is the Eocell Positive or Negative for the Galvanic/Voltaic cell?
Eocell = EMF is Positive
Describe the way that the Galvanic/Voltaic cell is set up
See attached
Describe the electrolytic cell delta G
Delta G > 0
nonspontaneous reaction
Describe the electrolytic cell Eocell, positive or negative
Eocell is negative
Describe the electrolytic cell
Anode is (+) and Cathode is (-)
Still electron moves from anode to cathode
Describe reduction potentials and Electromotive force (emf)
Eocell = Eocathode- Eoanode
Eo = standard EMF of reduction in volts
recall; cathode is positive reduction potential and anode is negative reduction potential
What is Faraday’s Law of Electrolysis equation and what is Faraday’s constant?
It = nF
I = current in A
t = time in s
n = moles of electrons
F = faraday’s constant in couloms/mol
F=105
Explain the equations used to calculate the Gibbs Free energy
Delta G = -nFEocell
Delta G = -RT*ln(Keq)
Therefore:
nFEocell = RT*ln(Keq)
Where: R = ideal gas constant in J/mol K
T = temperature in Kelvin
Explain Nuclear Reactions?
Some nuclei are unstable and spontaneously emit particles or radiation
The general reaction for decay:
AZX -> A’Z’Y + (emitted particles)
Indicating that the atom’s atomic number or mass number may change during decay
explain alpha decay
AZX -> A-4Z-2Y + alpha
Emission of an alpha-particle
alpha = two protons and two neutrons (essentially a helium nucleus 42He2+)
Recall:
A = atomic mass
Z = atomic number
Explain Beta Minus Decay (beta -): electron Emission
AZX -> AZ+1Y + e-
Emission of an electron
One of the atom’s neutrons turns into a proton during emission
Recall:
A = atomic mass
Z = atomic number
If 2027Co decayed via beta minus, what would it turn into?
2027Co —> 2027+1Ni + e-
would decay into Nickel
What is electron capture radiation reaction?
AZX + e- –> AZ-1Y
This is beta - minus decay in reverse
One of the atom’s protons turn into a neutron during capture
EX. 8137Rb + e- –> 8137-1Kr
Explain Beta Plus Decay: Positron Emission
AZX –> AZ-1Y + e-
Emission of a positron (+ electron) (denoted o+1e or Beta+)
One of the atom’s protons turns into a neutron
EX. 6027Co –> 6027-1Fe + e+
Explain Gamma Decay
AZX* –> AZY + gamma
Emission of a high-energy photon
There are no changes to the atom’s atomic or mass number in gamma decay
Explain how to determine half life
See attached
What are the easy solubility rules that you should know for test day?
- All salts of alkali metals are water soluble.
- All nitrates are water soluble.
- All salts of the ammonium ion (NH4+) are water soluble.
What is easy to know about insoluble molecule rules for test day?
- All carbonates, phosphates, sulfides, and sulfites are insoluble, except when they are complexed with alkali metals or ammonium.
- To put it another way, carbonates, phosphates, sulfides, and sulfites are always insoluble, unless you mix them with the elements that are always soluble.
When aren’t chlorides, bromides, and iodides are water soluble?
All chlorides, bromides, and iodides are water soluble, except when they contain Ag+, Pb2+, and Hg2+
Note: flourine does not follow these rules
Explain the calcium, strontium, barium rules of solubility
- All metal oxides are insoluble with the exception of CaO, SrO, BaO and alkali metal oxides.
- Hydroxides are insoluble, with the exception of Ca2+, Sr2+, Ba2+, and alkali metal hydroxides.
- All sulfates are soluble, with the exception of those containing Ca2+, Sr2+, and Ba2+.
explain a summary of solubility
see attached
How do you calculate the % Composition by Mass.
Perhaps the most straightforward, the percentage composition by mass is simply:
Mass of solute/Mass of solution * 100%
Example
What is the percent composition by mass of a salt water solution if 100g of the solution contains 20g of NaCl?
Well, mass of solute/mass of solution in this case means 20g NaCl/100g of solution * 100% = 20%. Not too difficult.
How do you calculate the Mole Fraction?
Mole fraction = # moles compound / # moles of all species in the system
In an exothermic reaction, what sign is delta H?
Negative!!!!!
What is this?
methyl acetate
What is this?
Acetylene
sp hybridized carbons
What is the difference between accuracy and precision?
Accuracy = measurement to actual value
Precision = how close each measurement is
What measurement instruments are Not calibrated?
Test tube
Beaker
Erlinmeyer flasks
Round-bottom flasks
Transfer (or pasteur) pipets
Petridishes
Watch glass
bottles
jars
vials
What are calibrated glass ware?
Craduated cylinders
Buret (used for titrations)
Graduated Pipets (or volumentric pipets)
Volumetric Flask = make solutions
What are the different types of pH measurement tools?
- pH meter, (glass bulb), large calibration range for solutions = 4, 7, 10
- Litmus paper
Name and describe the two types of weight determination devices
- Standard Balance = top loaded and require accuracy in miligram range, within +/- 0.5 mg
- Analytical Balance = more sensitive application +/- 0.01 mg accuracy. have glass sliding doors
What is an atom?
Basic building block of matter, smallest unit
- Composed of subunits: proton, neutron, electron
- Proton and neutron = nucleus (+ charge)
- Electrons = in the cloud (- charge)
Explain subatomic particles (John Dalton) and how they relate to atoms, elements, compounds and reactions
- All elements are composed of very small particles = atoms
- The atoms of one element are different from atoms of all other elements
- All compounds are composed of atoms of more than one element
- A given chemical reaction involves only the separation, combination, or rearrangement of atoms
