6.4 Rates of Reaction Flashcards
1
Q
How can rate of reaction be observed?
A
Either by measuring how quickly the reactants are used up or how quickly the products are formed.
2
Q
What does the collision theory state?
A
It states that the rate of a reaction depends on:
- The collision frequency of reacting particles (how often they collide). The more frequent the collisions are, the faster the reaction is.
- The energy transferred during a collision. Particles have to collide with enough energy for the collision to be successful.
3
Q
Describe why a higher temperature increases rate of reaction
A
- When the temperature is increased the particles move faster. If they move faster, they’re going to have more frequent collisions.
- Higher temperatures also increase the energy of the collisions, since the particles are moving faster. Reactions only happen if the particles collide with enough energy.
- This means that at higher temperatures there will be more frequent successful collisions (more particles will collide with enough energy to react).
4
Q
Describe why increasing concentration (or pressure) increases rate of reaction
A
- If a solution is made more concentrated, it means there are more particles of reactant in the same volume. This makes collisions more likely, so the reaction rate increases.
- In a gas, increasing the pressure means that the particles are more crowded. This means that the frequency of collisions between particles will increase - so the rate of reaction will also increase.
5
Q
Describe why a higher surface area means a higher rate of reaction
A
- If one reactant is a solid, breaking it into smaller pieces will increase its surface area to volume ratio (i.e. more of the solid will be exposed, compared to its overall volume)
- The particles around it will have more area to work on, so the frequency of collisions will increase.
- This means that the rate of reaction is faster for solids with a larger surface area to volume ratio
