General and Physical Chemistry Cheat Sheet

This cheat sheet covers fundamental concepts in General and Physical Chemistry, including atomic structure, periodic trends, chemical bonding, gas laws, chemical equilibrium, thermodynamics, reaction kinetics, and electrochemistry.

Core Principles

Atomic Structure: Atoms are composed of protons, neutrons, and electrons, with the identity of an atom determined by its proton number.
Periodic Trends: Atomic radius, electronegativity, and ionization energy exhibit predictable patterns across the periodic table.
Chemical Bonding: Atoms form ionic or covalent bonds by transferring or sharing electrons to achieve stable electron configurations.
Gas Laws: The behavior of gases is described by relationships between pressure, volume, temperature, and the number of moles, as summarized by the ideal gas law (PV=nRT).
Chemical Equilibrium: Reversible reactions reach a dynamic equilibrium where the rates of the forward and backward reactions are equal, and Le Chatelier's principle describes how equilibrium shifts in response to changes in conditions.
Thermodynamics: Enthalpy (ΔH) represents the heat energy change in a reaction, while entropy (ΔS) measures disorder, and the Gibbs free energy (ΔG) determines the spontaneity of a process.

Formulas

Mass Number = Number of protons + Number of neutrons
Relative atomic mass of oxygen = (16 × 99.76 %) + (17 × 0.04 %) + (18 × 0.20 %) = 16.00
Avogadro's Law: $ \frac{V_1}{n_1} = \frac{V_2}{n_2} $
Boyle's Law: $ P_1V_1 = P_2V_2 $
Charles's Law: $ \frac{V_1}{T_1} = \frac{V_2}{T_2} $
Ideal Gas Law: $ PV = nRT $
pH = -log10[H+] for acids
[H+] = 10-pH
pOH = -log10[OH-] for bases
pH + pOH = 14
Rate Law: $ \text{rate} = k[A]^m[B]^n $
No. of mole (mol) = mass (g) ÷ molar mass (g/mol)
Standard Enthalpy Change of Reaction: $ \Delta_{rxn}H^\circ = \sum n_p \Delta_f H^\circ (\text{products}) - \sum n_r \Delta_f H^\circ (\text{reactants}) $
ΔG = ΔHsystem - TΔSsystem
ΔSuniv = ΔSsystem + ΔSsurroundings
ΔSuniv = +ve for spontaneous process
ΔSuniv = 0 for equilibrium process
ΔG = -TΔSuniverse
ΔG is negative for spontaneous process
Rate of reaction = $ \frac{1}{a} \frac{\Delta[A]}{\Delta t} = -\frac{1}{b} \frac{\Delta[B]}{\Delta t} = \frac{1}{c} \frac{\Delta[C]}{\Delta t} = \frac{1}{d} \frac{\Delta[D]}{\Delta t} $
Zero order – rate = k
1st order – rate ∝ [reactant]
2nd order – rate ∝ [reactant]²
Zero order half-life: $ t_{1/2} = \frac{C_o}{(2k)} $
First order half-life: $ t_{1/2} = \frac{\ln 2}{k} $
Second order half-life: $ t_{1/2} = \frac{1}{kC_o} $
k = Ae(-Ea/RT)
E°cell = E°oxidation + E°reduction
E°cell > 0, Positive E°cell → Spontaneous reaction
E°cell < 0, Negative E°cell → Non-spontaneous reaction