Chemistry

Question 1

.Light

Energy of an electromagnetic wave

Answer 1

E - energy of the wave λ - wavelength f - frequency c - speed of light in a vacuum h - Planck’s constant

Question 2

Constants

Speed of Light:

Answer 2

Question 3

Light

Rydberg equation

Answer 3

R - the Rydberg constant n - orbital levels λ - wavelength of photon

Question 4

Compounds and Stoichiometry

Equation for moles

Answer 4

Mass of substance: The actual weight of the substance you're measuring. Molar mass: The mass of one mole of the substance, typically expressed in grams per mole (g/mol). It can be calculated by adding the atomic masses of all atoms in the molecule, based on the periodic table.

Question 5

Compounds and Stoichiometry

Equation for Gram Equivalent Weight (GEW)

Answer 5

Molar Mass: The mass of one mole of the substance, in grams per mole (g/mol). n-factor: The number of equivalents per mole of the substance, which depends on the context (See Below):

For acids: The number of replaceable hydrogen ions (H⁺) per molecule.
For bases: The number of hydroxide ions (OH⁻) the base can donate.
For salts: The total charge of cations or anions.
For redox reactions: The number of electrons lost or gained per molecule or ion.

Question 6

Compounds and Stoichiometry

Equation for Equivalents

Answer 6

Question 7

Compounds and Stoichiometry

Equation for Molarity

Answer 7

Question 8

Compounds and Stoichiometry

Equation for Percent Compostion

Answer 8

Mass of element in compound: The total mass of a specific element in the compound, often calculated by multiplying the element’s atomic mass by the number of its atoms in the molecular formula.
Total molar mass of compound: The sum of the molar masses of all elements in the compound.

Question 9

Compounds and Stoichiometry

Equation for Percent Yield

Answer 9

Actual Yield: The amount of product actually obtained from the experiment or reaction, measured in grams, moles, or other units.
Theoretical Yield: The maximum possible amount of product that could be formed based on stoichiometric calculations, assuming perfect reaction conditions with no losses.

Question 10

Chemical Bonding

What’s the formula to calculate the force between the atoms in an ionic bond

Answer 10

F ∝ q1*q2 / r2

q1 and q2 = charge magnitude of the ions
r = distance between the ions

Question 11

Chemical Bonding

What is the electrostatic energy (Ees) of an ionic bond?

Answer 11

Ees ∝ q1*q2 / r

This holds for all charged particles, and thus can be applied to calculate energy between the atoms in an ionic bond.

q1 and q2 = charge magnitude of the atom
r = distanc

Question 12

Equation to calculate the rate constant of a reaction: Arrhenius Equation

Answer 12

k = rate constant A = pre-exponential factor Ea = activation energy in J/mol R = gas constant = 8.314 J mol-1 K-1 T = temperature in Kelvin

Question 13

Avogadro’s number

Answer 13

Question 14

Used to determine the equilibrium concentrations of different reagents in a reversible reaction (ex. aA + bB ⇌ cC + dD)

Answer 14

Keq = equilibrium constant unitless [A] = equilibrium concentration of reactant A in molarity [B] = equilibrium concentration of reactant B in molarity [C] = equilibrium concentration of product C in molarity [D] = equilibrium concentration of product D in molarity a = coefficient of reactant A unitless b = coefficient of reactant B unitless c = coefficient of product C unitless d = coefficient of product D unitless

Question 15

Molality

Formula for the concentration of a solution in molality

Answer 15

Question 16

Molarity
Formula for the concentration of a solution in molarity.

Answer 16

Question 17

Formula for the reaction quotient for the equilibrium reaction aA + bB ⇌ cC + dD.

Answer 17

Qc = reaction quotient unitless [A] = concentration of reactant A in molarity [B] = concentration of reactant B in molarity [C] = concentration of product C in molarity [D] = concentration of product D in molarity a = coefficient of reactant A unitless b = coefficient of reactant B unitless c = coefficient of product C unitless d = coefficient of product D unitless

Used to compare reaction conditions to equilibrium conditions by comparing Qc to Keq. Qc = Keqat equilibrium.

Question 18

Relationship of K and Q

Answer 18

Used to determine which direction a reaction will shift to reach equilibrium.
If K > Q, a reaction will proceed forward, converting reactants into products.
If K < Q, the reaction will proceed in the reverse direction, converting products into reactants.

Question 19

First law of thermodynamics

Answer 19

ΔU = Q - W

ΔU - change in internal energy of the system
Q - heat entering the system
W - work done by the system

Question 20

R Gas constant

Answer 20

Question 21

1 atm equivalents

Answer 21

Question 22

Ideal Gas Law

Answer 22

P = pressure in Pa or atm

V = volume in m3

n = moles of gas

R = ideal gas constant = 8.314 J mol-1 K-1 (if P in Pa) = 0.0821 L atm mol-1 K-1 (if P in atm)

T = temperature in Kelvin

Combines Boyle’s law, Charles’ law, and Avogadro’s law.

Used to determine pressure, volume, moles, or temperature of a gas

Question 23

Density of Gas

Answer 23

Question 24

Combined Gas Law

Answer 24

Question 25

Avogadro’s Law | Used to calculate the amount in moles or volume of a gas in response to

Answer 25

| volume of a gas and moles are proportional at constant temp & pressure.

Question 26

Boyle’s Law (Used to calculate the resulting pressure or volume of a gas in response to a change in either.)

Answer 26

P1 = initial pressure in atm (most common) V1 = initial volume in L (most common) P2 = final pressure in same units as P1 V2 = final volume in same units as V1 ## Footnote States that the pressure and volume of a gas are inversely proportional at constant temperature.

Question 27

Charles’ Law (Used to calculate the resultant volume or temperature of a gas in response to a change in either.)

Answer 27

| States that the volume and temperature of a gas are directly proportiona

Question 28

Gay-Lussac's Law (Used to calculate the resultant pressure or temperature of a gas in response to a change in either.)

Answer 28

Question 29

Dalton’s Law of Partial Pressures (Used to calculate the total pressure of a sample of multiple gases or the partial pressure of one gas in a sample of multiple gases.)

Answer 29

States that the total pressure of a sample of multiple gases is equal to the sum of the partial pressures of the individual gases.

Question 30

Kinetic Energy | Formula for the kinetic energy of a moving object

Answer 30

KE = kinetic energy in J m = mass in kg v = speed in m/s

Question 31

Raoult’s Law (AKA Daltons Partial Pressure) (Used to calculate the vapor pressure of solutions or the partial vapor pressures of many liquids in a mixture)

Answer 31

States that the vapor pressure of a volatile liquid in a solution is scaled by its mole fraction in the mixture PA = vapor pressure of solution in atm (most common) XA = mole fraction of the solvent unitless P°A = vapor pressure of solvent in same units as PA

Question 32

Van der Waals Equation of State (Used to compare real values of pressure to those calculated by the Ideal Gas Law.)

Answer 32

Describes the pressure of real gases, in contrast to ideal gases, by considering the molar volume (constant b) and intermolecular interactions (constant a) of a given gas. P = pressure in Pa (N/m2) n = amount of gas in moles R = ideal gas constant = 8.314 J mol-1 K-1 T = temperature in Kelvin V = molar volume in m3 b = volume occupied by individual gas molecules in m3/mol a = average attraction between gas molecules in Pa m6 mol-2

Question 33

Average Kinetic Energy of Gas (Used to calculate average kinetic energy or temperature when the other is known.)

Answer 33

States that the temperature of a gas is directly proportional to the average kinetic energy of its particles. KEavg = average kinetic energy of a gas particle in J kB = Boltzmann constant = 1.38 x 10-23 J/K T = temperature in Kelvin

Question 34

Molality: Formula for the concentration of a solution in molality.

Answer 34

Question 35

Raoult’s Law: Used to calculate the vapor pressure of solutions or the partial vapor pressures of many liquids in a mixture.

Answer 35

PA = vapor pressure of solution in atm (most common) XA = mole fraction of the solvent unitless P°A = vapor pressure of solvent in same units as PA States that the vapor pressure of a volatile liquid in a solution is scaled by its mole fraction in the mixture.

Question 35

Freezing Point Depression

Answer 35

𝛥Tf = freezing point depression in Kelvin or ℃ i = van’t Hoff factor of solute unitless Kf = cryoscopic constant in K kg mol-1 m = molality of solution in mol/kg Describes the degree of freezing point depression of a liquid with a given concentration of solutes.

Question 36

Formula for the reaction quotient for the equilibrium reaction aA + bB ⇌ cC + dD.

Answer 36

Qc = reaction quotient unitless [A] = concentration of reactant A in molarity [B] = concentration of reactant B in molarity [C] = concentration of product C in molarity [D] = concentration of product D in molarity a = coefficient of reactant A unitless b = coefficient of reactant B unitless c = coefficient of product C unitless d = coefficient of product D unitless Used to compare reaction conditions to equilibrium conditions by comparing Qc to Keq. Qc = Keqat equilibrium.

Question 36

Dilution Formula: Used to calculate the amount of solvent required for the desired dilution or to calculate resultant concentration after dilution with a known amount of solvent

Answer 36

Mi = initial concentration in molarity Vi = initial volume in L Mf = final concentration in molarity Vf = final volume in L

Question 37

Formula for the equilibrium constant for the reaction aA + bB ⇌ cC + dD.

Answer 37

Keq = equilibrium constant unitless [A] = equilibrium concentration of reactant A in molarity [B] = equilibrium concentration of reactant B in molarity [C] = equilibrium concentration of product C in molarity [D] = equilibrium concentration of product D in molarity a = coefficient of reactant A unitless b = coefficient of reactant B unitless c = coefficient of product C unitless d = coefficient of product D unitless Used to determine the equilibrium concentrations of different reagents in a reversible reaction.

Question 38

Molarity: Formula for the concentration of a solution in molarity.

Answer 38

Question 38

Boiling Point Elevation: Describes the degree of boiling point elevation of a liquid with a given concentration of solutes.

Answer 38

𝛥Tb = boiling point elevation in Kelvin or ℃ i = van’t Hoff factor of solute unitless Kb = ebullioscopic constant in K kg mol-1 m = molality of solution in mol/kg

Question 39

Osmotic Pressure: Used to estimate the ability of a solution to accept solvent by osmosis.

Answer 39

𝛱 = osmotic pressure in pascals or atm i = van’t Hoff factor unitless M = concentration of solution in molarity R = ideal gas constant = 8.314 J mol-1 K-1 (if 𝛱 in Pa) = 0.0821 L atm mol-1 K-1 (if 𝛱 in atm) T = temperature in Kelvin Formula for the osmotic pressure, the minimum pressure required to prevent a solvent from moving across a semipermeable membrane.

Question 40

Percent Composition by Mass

Answer 40

mass of solute in grams (most common) mass of solution in same units as mass of solute

Question 41

Acid Dissociation Constant

Answer 41

Ka = acid dissociation constant unitless [H3O+] = concentration of hydronium ions in molarity [A‒] = concentration of conjugate base in molarity [HA] = concentration of acid in molarity Used to determine the concentrations of species in an aqueous acid at equilibrium.

Question 42

Henderson-Hasselbach Equation: Used to calculate the pH of buffers.

Answer 42

pH = pH of buffer unitless pKa = pKa of acid unitless [A‒] = concentration of conjugate base in molarity [HA‒] = concentration of acid in molarity Equation relating the pH of an acid buffer to the ratio acid to conjugate base in solution.

Question 43

Nernst Equation: Equation for the cell potential of an electrochemical cell at non-standard conditions.

Answer 43

Ecell = non-standard cell potential E°cell = standard cell potential R = gas constant = 8.314 J mol-1 K-1 T = temperature in Kelvin n = number of moles of electrons transferred in reaction unitless F = Faraday constant = 96485 J V-1 mol-1 Q = reaction quotient unitless

Question 44

pH Formula

Answer 44

pH unitless [H+] = concentration of hydrogen ions in molarity

Question 45

pOH Formula

Answer 45

pOH unitless [OH‒] = concentration of hydroxide ions in molarity

Question 46

Henderson-Hasselbach Equation: Used to calculate the pOH of buffers.

Answer 46

pOH = pOH of buffer unitless pKb = pKb of base unitless [HB+] = concentration of conjugate acid in molarity [B] = concentration of base in molarity Equation relating the pOH of a base buffer to the ratio between base and conjugate acid in solution.

Question 47

Relationship of Ka and Kb: Used to calculate the Ka of an acid when the Kb of its conjugate base is known, or to calculate the Kb of a base when the Ka of its conjugate acid is known

Answer 47

Question 48

Cell Potential: Formula for the cell potential of an electrochemical cell with known half-reaction standard reduction potentials.

Answer 48

E°cell = cell potential in V E°cathode = standard reduction potential of the cathode in V E°anode = standard reduction potential of the anode in V

Question 49

Equivalence Point

Answer 49

Na = normality of acid in equivalents/L Va = volume of acid in L Nb = normality of base in equivalents/L Vb = volume of base in L

Question 50

Gibbs Free Energy of Cell: Describes the relationship between an electrochemical cell’s cell potential and the Gibbs free energy change of its redox reaction.

Answer 50

𝛥G° = Gibbs free energy change in J/mol n = number of moles of electrons transferred in reaction unitless F = Faraday constant = 96485 J V-1 mol-1 E°cell = cell potential in V

Question 51

Gibbs Free Energy of Cell: Describes the relationship between a reaction’s equilibrium constant and its Gibbs free energy change.

Answer 51

𝛥G° = Gibbs free energy change in J/mol R = gas constant = 8.314 J mol-1 K-1 T = temperature in Kelvin Keq = equilibrium constant unitless

Question 52

Gibbs Free Energy of Cell: Formula for the Gibbs free energy change of a reaction at non-standard conditions.

Answer 52

𝛥G = non-standard Gibbs free energy change in J/mol 𝛥G° = standard Gibbs free energy change in J/mol R = gas constant = 8.314 J mol-1 K-1 T = temperature in Kelvin Q = reaction quotient unitless

Question 53

Autoionization Constant (Water): Used to calculate hydronium concentration or hydroxide concentration when the other is known

Answer 53

Kw = autoionization constant unitless [H3O+] = concentration of hydronium ions in molarity [OH‒] = concentration of hydroxide ions in molarity States that the product of hydronium concentration and hydroxide concentration equal the autoionization constant, 10-14.