High School Chemistry - Fall 2024 Summary

Vocabulary flashcards for High School Chemistry - Fall 2024 Summary

Rate of Reaction

How fast a chemical reaction happens; how quickly reactants turn into products.

Factors Affecting Reaction Rate

Higher temperature, more particles, more surface area, catalyst, and nature of reactants.

Half-Life (1st Order)

Time it takes for half of the substance to disappear; constant in first-order reactions.

Energy Diagram

Reactants -> peak (activation energy) -> products. Catalyst lowers the peak.

Mechanism Rate Law

Match rate law to the slow step of the mechanism.

Equilibrium Expression

K = [C]^c [D]^d / [A]^a [B]^b (no solids or liquids).

Equilibrium Check

Q = K -> equilibrium; Q < K -> forward shift; Q > K -> backward shift

Equilibrium Direction

K > 1 -> products; K < 1 -> reactants. Lower pKa = stronger acid. Negative deltaG = spontaneous.

Ka, pH, and pKa for Weak Acids

Ka = [H+][A-]/[HA] Use ICE table -> [H+] -> pH = -log[H+] pKa = -log(Ka)

Q vs. K Shifts

Q < K -> right (products); Q > K -> left (reactants)

Equilibrium Shifts

Add reactants -> right; remove products -> right; increase pressure -> fewer gas molecules; increase temp -> endothermic side.

Buffer

Weak acid + conjugate base; absorbs H+ or OH- to resist pH changes.

pH of a Buffer

pH = pKa + log([A-]/[HA]); use stoichiometry then recalculate if acid/base added.

pH of Salt Solutions

NaCl -> neutral; NH4Cl -> acidic; NaCH3COO -> basic. Depends on the ions from the salt.