GCSE Chemistry Quiz: The Rate and Extent of Chemical Change (AQA Topic 6)

What is the formula to calculate the rate of reaction in terms of amount of product formed over time?

Which unit could be used for the rate of reaction when measuring quantity in terms of moles?

What does the activation energy represent in a chemical reaction?

How do factors like concentration and surface area influence the rate of a chemical reaction?

Why is temperature considered a factor that affects the rates of chemical reactions?

What effect does increasing the temperature have on the rate of a chemical reaction?

Which of the following best describes the role of catalysts in chemical reactions?

Why are catalysts not included in the equation for a reaction?

What specific effect do enzymes have in biological systems as catalysts?

How do catalysts affect the activation energy of a chemical reaction?

Calculating Rates of Reactions

Rates of reactions can be measured using the amount of reactant used or product formed over time
Formula for rate of reaction: Rate of reaction = amount of reactant used ÷ time or Rate of reaction = amount of product formed ÷ time
Quantity of reactant or product can be measured by mass in grams or by volume in cm³
Units of rate of reaction may be given as g/s or cm³/s
Quantity of reactants can also be measured in terms of moles, with units of rate of reaction as mol/s
To find the rate of reaction graphically, draw tangents to curves and use the slope of the tangent

Factors Affecting Rates of Chemical Reactions

Concentration of reactants
Pressure of reacting gases
Surface area of solid reactants
Temperature
Catalysts

Collision Theory and Activation Energy

Collision theory: chemical reactions can occur only when reacting particles collide with each other and with sufficient energy
Activation energy: the minimum amount of energy that particles must have to react
Increasing concentration, pressure, and surface area increases the frequency of collisions and thus the rate of reaction
Increasing temperature increases the frequency of collisions and makes them more energetic, thus increasing the rate of reaction

Catalysts

Substances that speed up chemical reactions without being changed or used up during the reaction
Enzymes act as catalysts in biological systems
Catalysts decrease the activation energy, increasing the proportion of particles with energy to react
Catalysts provide a different pathway for a chemical reaction with a lower activation energy

Test your knowledge on calculating rates of reactions, measuring rates of reactions, and understanding the factors affecting the rate of reaction. This quiz covers concepts related to the rate and extent of chemical change in the context of AQA GCSE Chemistry Topic 6.