6.2 Rate of Reaction
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3. What is the effect of changing the concentration of solutions on the rate of reaction?
Increasing the concentration increases the rate of reaction.
4. How does changing the pressure of gases affect the rate of reaction?
Increasing the pressure of gaseous reactants increases the rate of reaction.
5. What happens to the rate of reaction when the surface area of solid reactants is changed?
Increasing the surface area of a solid (by breaking it into smaller pieces) increases the rate of reaction.
6. Describe the effect of temperature on the rate of reaction.
Increasing the temperature increases the rate of reaction.
7. What is the effect of adding or removing a catalyst, including enzymes, on the rate of reaction?
Adding a catalyst increases the rate of reaction, while removing it would cause the rate to return to its uncatalyzed speed.
8. Define a catalyst.
A substance that increases the rate of a reaction and remains chemically unchanged at the end of the reaction.
9. List two practical methods for investigating the rate of a reaction.
Measuring the change in mass of a reactant or a product over time, and measuring the volume of a gas formed over time.
10. How is the rate of reaction interpreted from an experimental data graph?
The steepness (or gradient) of the slope represents the rate of reaction; the steeper the line, the faster the reaction is occurring. For curved graphs, the rate at a specific point can be determined by calculating the gradient of a tangent drawn to the curve.
11. Describe collision theory in terms of the number of particles.
Collision theory considers the number of particles per unit volume in a system.
12. How does collision theory define the frequency of collisions?
It refers to how often particles collide with each other per unit of time.
13. What role does kinetic energy play in collision theory?
Particles must have sufficient kinetic energy to overcome the activation energy barrier during a collision for a reaction to occur.
14. Relate activation energy (Ea) to collision theory.
A collision is only "effective" or successful if the colliding particles possess energy equal to or greater than the activation energy.
15. Explain the effect of concentration on reaction rate using collision theory.
Increasing concentration increases the number of particles per unit volume, which increases the frequency of collisions between particles.
16. Explain the effect of gas pressure on reaction rate using collision theory.
Increasing pressure increases the number of gas particles per unit volume, leading to an increased frequency of collisions.
17. Explain the effect of solid surface area on reaction rate using collision theory.
Increasing the surface area exposes more particles to collisions, thereby increasing the frequency of collisions.
18. Explain the effect of temperature on reaction rate using collision theory.
Increasing temperature increases the kinetic energy of particles, making them move faster and collide more frequently; additionally, a higher proportion of particles will have energy greater than the activation energy.
19. Explain the effect of a catalyst on reaction rate using collision theory.
A catalyst increases the rate by providing an alternative reaction pathway with a lower activation energy (Ea), meaning more particles have enough energy to react upon collision.