Rates of reaction (every paper)

Every rate answer = collisions. Temperature changes the ENERGY; concentration/area change the FREQUENCY.

The four factors, one line each

Temperature ↑ → greater proportion of particles with E ≥ Eₐ → more successful collisions.
Concentration/pressure ↑ → particles per volume ↑ → collision frequency ↑.
Surface area ↑ → more exposed particles → more sites.
Catalyst → alternative pathway, lower Eₐ (profile peak lower, ΔH unchanged).

Frequency vs energy — which factors affect which

FREQUENCY of collisions changes with: concentration, pressure, surface area.
ENERGY of collisions (proportion exceeding Eₐ) changes with: temperature, and the presence of a catalyst (via a lower Eₐ pathway).

ℹ

Profile question

Catalyst curves: draw BOTH peaks. Same reactant/product levels (same ΔH); catalysed peak clearly lower. Exam-style Increasing temperature affects rate AND total volume produced, in a gas-collection experiment The same amounts of Na₂CO₃(aq) and HCl(aq) react at 25 °C and at 50 °C, with CO₂ gas volume recorded over time on the same graph. Explain the effect of increased temperature. RATE: the 50 °C line rises MORE STEEPLY at the start, since a greater proportion of particles have E ≥ Eₐ at the higher temperature, producing more successful collisions per second. TOTAL VOLUME: both lines eventually reach the SAME final (plateau) height, since the same amount of limiting reactant is used in each — temperature changes how FAST the reaction finishes, not how MUCH gas is ultimately produced. GRAPH FEATURE: describe the 50 °C line reaching its plateau EARLIER (further left) than the 25 °C line, even though both plateaus sit at the same height. ✓ A complete answer separates the RATE effect (steeper line, earlier plateau) from the TOTAL AMOUNT effect (same final height) — treating them as the same thing misses half the instruction.

Practice for this standard covers the whole topic — flashcards and quiz.