Reading the notation

A small set of terms carries every part of this paper — the schedules reward the PRECISE word, not just the general idea.

6 terms

Cover the right column and check you can say what each one means.

Kc: The equilibrium constant — products (each raised to its coefficient) over reactants (each raised to its coefficient), for a reaction at equilibrium.
Position of equilibrium: Which side the equilibrium mixture favours — shifts with a change in concentration, pressure or temperature, but returns to a NEW equilibrium.
Value of Kc: Changes ONLY with temperature. Concentration, pressure and catalysts can shift the position of equilibrium, but the Kc value itself is unchanged unless temperature changes.
Eₐ (activation energy): The minimum energy a collision needs to succeed. Rate answers are graded on "a greater PROPORTION of particles with E ≥ Eₐ", not just "particles move faster".
Conjugate acid–base pair: Two species differing by exactly one H⁺ — the acid loses it to become its conjugate base; the base gains it to become its conjugate acid.
Amphiprotic: A species that can act as EITHER an acid or a base, depending on what it reacts with — water and hydrogen carbonate (HCO₃⁻) are the examples the papers use.

Identify which of the three recurring strands this part is: rates, equilibrium (including Kc), or acids and bases — each has its own checklist below.
Skim for a graph, an unknown solution to identify, or a base pH calculation — these signal the deeper skill sections further down this page.

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