AQA GCSE Chemistry: The Rate and Extent of Chemical Change Flashcards

Vocabulary-style flashcards covering calculating rates, collision theory, factors affecting rates, reversible reactions, equilibrium, and required practical methods based on the AQA GCSE Chemistry Unit 6 transcript.

Rate of a chemical reaction

How quickly a product is formed or how quickly a reactant is used up.

Successful collisions

Collisions between reactant particles that produce a chemical reaction because they occur with enough energy.

Mean rate of reaction (Formulas)

$\text{mean rate of reaction} = \frac{\text{quantity of reactant used}}{\text{time taken}}$ or $\text{mean rate of reaction} = \frac{\text{quantity of product formed}}{\text{time taken}}$

Grams per second ($g/s$) or grams per minute ($g/min$)

The units used for measuring the rate of reaction when monitoring the changing mass of a reaction mixture.

$cm^3/s$ or $cm^3/min$

The units used for measuring the rate of reaction when monitoring the changing volume of a gas produced.

Activation energy

The minimum amount of energy that particles must have to react.

Catalyst

A substance that speeds up a chemical reaction without getting used up itself by offering an alternative pathway at a lower activation energy.

Enzymes

Biological catalysts.

Surface area to volume ratio

A measurement that increases when a solid is broken into smaller lumps or crushed into a powder, exposing more of the solid to reactant particles.

Gradient

A value calculated from a graph to determine the rate of reaction, using the formula $\text{gradient} = \frac{y}{x}$.

Haber process

The industrial process for making ammonia from nitrogen and hydrogen using high temperature, high pressure, and an iron catalyst.

Haber process symbol equation

$$N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$$

Le Chatelier’s Principle

The principle stating that if the conditions of a reaction at equilibrium are changed (pressure, concentration, or temperature), the position of equilibrium will shift to counteract the change.

Dynamic equilibrium

A state reached in a closed system where the forward and reverse reactions occur at the same rate and the concentrations of all reactants and products remain constant.

Closed system

A system where nothing can get in or out, allowing a reversible reaction to reach dynamic equilibrium.

Reversible reaction

A reaction where the products can react together to reform the reactants, represented by the symbol $\rightleftharpoons$.

Hydrated copper sulfate

A blue substance that contains water; its formula is $CuSO_4.5H_2O(s)$.

Anhydrous copper sulfate

A white substance formed when hydrated copper sulfate is heated and the water evaporates ($CuSO_4(s)$).

Precipitate

A solid that is formed in a solution during a chemical reaction, such as the sulfur in the sodium thiosulfate and hydrochloric acid practical.

Equation for Required Practical 5 (Production of Gas)

$$CaCO_3 + 2HCl \rightarrow CaCl_2 + H_2O + CO_2$$

Equation for Required Practical 5 (Change in Colour)

$$Na_2S_2O_3 + 2HCl \rightarrow 2NaCl + H_2O + SO_2 + S$$

Temperature effect on particles

Increasing the temperature causes reactant particles to gain kinetic energy and move more quickly, resulting in more frequent successful collisions.