Chemistry 112 Equations Summary

Flashcards of key Chemistry equations

[c] = kP

Used for Henry’s Law: solubility of gas in liquid

P = χP°

Used for Raoult’s Law: partial vapor pressure

ΔP = χP°

Change due to solute addition

P_total = χA·P°A + χB·P°B

Total pressure in a solution

ΔTf = i·Kf·m

Freezing point depression

ΔTb = i·Kb·m

Boiling point elevation

π = iMRT

Osmotic pressure

q = msΔT

Heat change in substance

q = nΔH

Heat from reaction or phase change

q_total = Σq

Total heat of system

S = k lnW

Statistical entropy

ΔS° = ΣS°products − ΣS°reactants

Entropy change

ΔG = ΔH − TΔS

Predict spontaneity

ΔG° = −RT lnK

Free energy from K

Kp = Kc(RT)^Δn

Convert between Kp and Kc

pH = −log[H+]

Calculate acidity

pH + pOH = 14

Relationship at 25°C

pH = pKa + log([A]/[HA])

Buffer equation

E°cell = E°cathode − E°anode

Standard cell potential

ΔG = −nFE

Free energy from redox

E = E° − (0.0592/n) logQ

Nernst equation

rate = k[A]^m[B]^n

General rate law

t½ = 0.693/k

Half-life for 1st order

k = Ae^(−Ea/RT)

Arrhenius equation

ΔE = Δm·c²

Nuclear binding energy

In(No/N) = kt

Used for Radioactive decay