Chem II Lab Final

Rate equation for reactants

Rate = -Δ[reactant]/Δt

Rate equation for products

Rate = Δ[product]/Δt

Overall reaction order

The sum of all individual exponents in the rate law.

Determining individual reaction orders

Use the method of initial rates and compare rate changes with concentration changes.

Rate law expression from data

Rate = k[A]^m[B]^n, solving for m and n using experimental data.

Effect of increasing concentration on reaction rate

It increases the frequency of collisions, which increases the rate.

Effect of increasing temperature on reaction rate

It increases particle energy, making collisions more effective.

Half-reaction method

Split the reaction into oxidation and reduction half-reactions, balance each, and then combine.

Rate constant (k)

A proportionality constant in the rate law that depends on temperature.

Monodentate ligand

A ligand that donates one pair of electrons to the metal.

Bidentate ligand

A ligand that donates two pairs of electrons to the metal.

Electromagnetic radiation arranged by frequency

Gamma > X-ray > UV > Visible > IR > Microwave > Radio.

Electromagnetic radiation arranged by wavelength

Radio > Microwave > IR > Visible > UV > X-ray > Gamma.

Purpose of color wheel

Helps determine the complementary color of a solution based on absorbed wavelength.

Equation for energy of radiation

E = hν or E = hc/λ.

Beer-Lambert Law

A = εbc, where A is absorbance, ε is molar absorptivity, b is path length, and c is concentration.

Absorbance calculation from transmittance

A = -log(T), where T = %T/100.

% transmittance calculation from absorbance

%T = 10^(-A) × 100.

Reaction quotient (Q)

Q = [products]^coeff / [reactants]^coeff using current concentrations.

Equilibrium constant (Kc)

Kc = [products]^coeff / [reactants]^coeff at equilibrium.

Calculating Kc from quantities

Plug equilibrium concentrations into Kc expression.

Le Châtelier’s Principle

A system at equilibrium will shift to oppose a disturbance.

Effect of concentration increase on equilibrium

The system shifts to consume the added substance.

Behavior of K with concentration changes

K remains constant unless temperature changes.

Effect of temperature increase on equilibrium in exothermic reaction

It shifts left; K decreases.

Effect of temperature increase on equilibrium in endothermic reaction

It shifts right; K increases.

Dissociation reaction of strong acid HCl

HCl → H⁺ + Cl⁻.

Dissociation reaction of weak acid HA

HA ⇌ H⁺ + A⁻.

Ka expression for weak acid

Ka = [H⁺][A⁻]/[HA].

Calculating [H3O⁺] from pH

[H3O⁺] = 10^(-pH).

Calculating [OH⁻] from pOH

[OH⁻] = 10^(-pOH).

Relationship between pH and pOH

pH + pOH = 14.

Calculating Ka from initial and equilibrium concentrations

Use ICE table and plug values into Ka = [H⁺][A⁻]/[HA].

Finding equilibrium concentrations from Ka and [HA]initial

Use an ICE table and solve for unknowns.

Determining acidity of a salt solution

Based on the nature of the cation and anion (acidic, basic, or neutral).

Components of a buffer

A weak acid and its conjugate base (or vice versa).

Buffer with highest capacity

One with high, equal concentrations of acid and base.

Calculating pH of a buffer

Use Henderson-Hasselbalch: pH = pKa + log([A⁻]/[HA]).

Dissolution equation for AgCl

AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq).

Ksp expression for AgCl

Ksp = [Ag⁺][Cl⁻].

Comparing Ksp values

Higher Ksp indicates more soluble in water.

Effect of temperature on Ksp in endothermic process

Ksp increases with temperature.

Effect of temperature on Ksp in exothermic process

Ksp decreases with temperature.

Calculating solubility from Ksp

Set up ICE table and solve using Ksp = x² (or other forms).

Common ion effect

Solubility decreases in the presence of a common ion.

Calculating temperature for spontaneity

T = ΔH° / ΔS°.

Gibbs Free Energy equation

ΔG° = ΔH° – TΔS°.

Condition for spontaneous reaction

When ΔG° < 0.