4-Rates Of Reaction

Question 0

What happens to the rate of reaction at a low temperature?

Answer 0

When cold particles move relatively slowly so collide less often, with less energy so few collisions are successful. This slows down the rate of reaction.

Question 1

What are the 5 factors that affect the rate of a reaction?

Answer 1

1. Temperature
2. Concentration of solutions
3. Pressure of gases
4. SA of solids
5. Use of a catalyst

Question 2

What happens to the rate of reaction at a high temperature?

Answer 2

Particles move more quickly and collide more often with more energy so more collisions successful. This speeds up the rate of reaction.

Question 3

What happens to the rate of reaction at a low concentration?

Answer 3

Particles are spread out so collide less often, slows down the rate of reaction.

Question 4

What happens to the rate of reaction at a high concentration?

Answer 4

Particles are crowded close together so collide more often, speeds up the rate of reaction.

Question 5

What happens to the rate of reaction when there is a low pressure?

Answer 5

Slows down as particles are spread out and collide less often.

Question 6

What happens to the rate of reaction at a high pressure?

Answer 6

Speeds up as particles are crowded close together and collide more often.

Question 7

What unit is concentration measured in?

Answer 7

Moles per cubic decimetre or mol/dm3 <— cubed

Question 8

What happens to the rate of reaction when you use large pieces (small SA to volume)?

Answer 8

Slows down as less particles are exposed and available for collisions.

Question 9

What happens to the rate of reaction when you use lots of small pieces (large SA to volume)?

Answer 9

Speeds up as more particles are exposed and available for collisions.

Question 10

What is a catalyst?

Answer 10

Something that increases the rate of reactions without being used up or altered. They can be used over and over to increase the rate of reaction.

Question 11

How do catalysts work?

Answer 11

Decrease the amount of energy needed for successful collisions (activation energy). One way to do this is to provide a surface for molecules to attach to, increasing the chance of bumping into them.

Question 12

In which ways can the rate of a chemical reaction be found?

Answer 12

• Measuring amount of reactants/products formed

* Measuring the time taken

Question 13

What is the equation for working out the rate of a reaction?

Answer 13

Amount of reactant used
/product formed
———————————
Time taken

Question 14

Name some pros and cons of catalysts.

Answer 14

Pros:
*increase the rate of reaction, speeds up industrial processes
*reduce costs of industrial processes
*save energy
*help sustainable development
*can be used over and over again
Cons:
*some are expensive
*need to be separated from products
*need to be cleaned regularly to avoid them becoming poisoned