R2.2 How fast? The rate of chemical change (SL)
15 revision questions with answers for R2.2 How fast? The rate of chemical change (SL). Read them here, or play the set as a class game on the projector. Free to host, and students join with a code.
Change in concentration of a reactant or product per unit time?
- Yield
- Equilibrium constant
- Activation energy
- Rate of reactionRight answer
What this set covers
Reaction rates at SL: units of rate, average and instantaneous rate, collision theory, the Maxwell–Boltzmann distribution, and how temperature, surface area, pressure and catalysts change the rate, including measuring hydrogen with a gas syringe.
- Common mix-up
- Students often say a catalyst changes ΔH or raises particle energy: it provides a pathway with lower activation energy and leaves ΔH unchanged.
- Revision tip
- Sketch the Maxwell–Boltzmann curve at two temperatures with Eₐ marked, and explain in one sentence why the shaded area beyond Eₐ grows.
All 15 questions and answers
Change in concentration of a reactant or product per unit time?
Answer: Rate of reaction
Units of rate of reaction?
Answer: mol dm⁻³ s⁻¹
Average rate when [A] falls by 0.020 mol dm⁻³ in 10 s?
Answer: 0.0020 mol dm⁻³ s⁻¹
The rate at an instant is the gradient of which line to the concentration–time curve?
Answer: Tangent
Colliding particles react only with sufficient energy and the correct…?
Answer: Orientation
Graph of the spread of kinetic energies among gas particles?
Answer: Maxwell–Boltzmann distribution
The area under a Maxwell–Boltzmann curve represents the…?
Answer: Total number of particles
Raising the temperature makes the Maxwell–Boltzmann peak…?
Answer: Lower and shift right
Main reason a temperature rise greatly increases reaction rate?
Answer: More particles exceed Eₐ
Powdered CaCO₃ reacts faster with acid than lumps because of a larger…?
Answer: Surface area
Raising the pressure of reacting gases speeds the reaction mainly by increasing…?
Answer: Collision frequency
A catalyst speeds up a reaction by providing a pathway with lower…?
Answer: Activation energy
Effect of a catalyst on ΔH of a reaction?
Answer: No change
Rate of Mg + HCl can be followed with a gas syringe by measuring the…?
Answer: Volume of hydrogen
Reaction rate slows as a reaction proceeds because…?
Answer: Reactant concentration falls
Play it as a class game
Play this set opens it in splycr, where you can host it for your class straight away. Hosting needs no account: put the room code on the projector, and students join from a phone with the code and their first name. Each question plays as multiple choice, and the three wrong options were written for that question.