level: Level 1 of Chapter 9
Questions and Answers List
Rates of reactions
level questions: Level 1 of Chapter 9
| Question | Answer |
|---|---|
| Increasing the temperature increases the rate of reaction because? (2) | 1. Increased energy results in particles moving around more quickly, which increases the frequency of collisions 2. Proportion of successful collisions increases because the proportion of particles exceeding the activation energy increases |
| Increasing the temperature increases the rate of reaction because? (2) | 1. Increased energy results in particles moving around more quickly, which increases the frequency of collisions 2. Proportion of successful collisions increases because the proportion of particles exceeding the activation energy increases |
| What is reaction kinetics | The study of rates of chemical reactions |
| What is the formula for rate of a chemical reaction | change in amount of reactants or products ➗ time |
| What is the units used for rate of reaction | mol dm⁻³ s⁻¹ |
| Rate of reaction usually changes as the reaction proceeds ,why? | Because concentration of reactants is decreasing |
| What does the collision theory state? | That in order to react with each other, particles must collide in correct orientation and with sufficient energy |
| What is ineffective collision | When reactant particles collide they mey simply bounce off each other, without changing |
| What is effective collision | If particles do have enough energy to react, they may change into product particles when they collide |
| What is activation energy? | The minimum energy that colliding particles must possess for a collision to be effective |
| According to collision theory, a reaction will speed up if:(2) | 1. Frequency of collisions increases 2. Proportion of particles with energy greater than the activation energy increases |
| What is frequency of collisions | number of collisions per unit time |
| What is a catalyst | A substance that increases the rate of a reaction but remains chemically unchanged itself at end of reaction |
| In reactions involving solutions, more concentrated reactants have a faster rate of reaction. Why? | Because random motion of particles in solution results in more frequent collisions between reacting particles |
| Increasing the temperature increases the rate of reaction because? (2) | 1. Increased energy results in particles moving around more quickly, which increases the frequency of collisions 2. Proportion of successful collisions increases because the proportion of particles exceeding the activation energy increases |
| When a catalyst and the reactants in a catalysed reaction are in the same phase, we describe the catalyst as ... | Homogeneous catalyst |