C4 - Rates & Energy

Question 1

What is activation energy?

Answer 1

It the minimum amount of energy needed to start a reaction however every reaction activation energy, they all need a push to get it started

Question 2

What 4 things effect the rate of reaction?

Answer 2

1. Concentration
2. Temperature
3. Catalyst
4. Surface area

Question 3

What is the collisional theory?

Answer 3

For a chemical reaction to take place the reactant particles must collide first. For the collision to be effective the particles must have a high amount of activation energy

Question 4

For the following explain why increasing them increases the rate of reaction.

1. Temperature
2. Concentration
3. Surface area

Answer 4

1. At higher temperatures molecules move faster and have more kinetic energy therefore more collisions will occur
2. The higher the concentration the faster the reaction because reactions in a solution involve particles to collide
3. Increasing the surface area allows more particles to collide as there is more area to do so

Question 5

What is a catalyst?

Answer 5

A catalyst is a substance which speeds up a reaction, without being changed or used up in the reaction

Question 5

What is a exothermic reaction?

Answer 5

An exothermic reaction is one which transferees energy to the surroundings, usually in the form of heat and usually shown by a rise in temperature

Question 6

What is an endothermic reaction?

Answer 6

An endothermic reaction is one which takes in energy from the surroundings, usually in the form of heat and is usually shown by a fall in temperature

Question 7

What are the 3 different ways of measuring rates of reaction?

Answer 7

1. Precipitation - this is when the product of the reaction is a precipitate which clouds the solution
2. Change in mass - the quicker the mass decreases the faster the rate of reaction
3. Volume gas given off - the more gas given off the quicker the rate of reaction