Science Chemistry

Question 1

What is rate of reaction?

Answer 1

Rate of reaction is the speed at which a chemical reaction takes place

Question 2

What are the units for measuring rates of reaction?

Answer 2

g/s or g/min
cm^3/s or cm^3/min

Question 3

What factors can affect a rate of reaction?

Answer 3

-Temperature
-Particle size
-Catalysts

Question 4

What is collision theory?

Answer 4

Collision theory states that chemical reactions occur only when the reactant particles collide with sufficient energy to react.

Question 5

How does temperature affect the rate of reaction?

Answer 5

Increasing the temperature will increase the kinetic energy of the reactant particles. This results in more successful collisions between reactant particles and a faster rate of reaction.

Question 6

How can the surface area of a solid be increased?

Answer 6

By cutting the substance into small pieces, or by grinding it into a powder.

To summarise: large pieces = small surface area.

Question 7

How does changing the surface area increase the rate of reaction?

Answer 7

Bigger surface area = faster reaction

Smaller surface area = slower reaction

Question 8

What is concentration?

Answer 8

The concentration of a solution is a measure of the amount of a substance that it contains

Question 9

Use collision theory to explain how changing the pressure of gaseous reactants alters the rate of reaction.

Answer 9

If the pressure of gaseous reactants is increased, there are more reactant particles for a given volume. There will be more collisions and so the reaction rate is increased. The higher the pressure of reactants, the faster the rate of a reaction will be.

Question 10

Describe what the activation energy of a reaction is.

Answer 10

The activation energy is the minimum energy required for a reaction to occur

Question 11

What is a catalyst?

Answer 11

A catalyst is a substance that increases the rate of a chemical reaction without being changed in chemical composition or amount

Question 12

Explain how a catalyst affect the rate of a reaction

Answer 12

A catalyst increases the rate of reaction by lowering the activation energy.

Question 13

What is a control variable?

Answer 13

A variable that must be kept the same

Question 14

What is a dependent variable?

Answer 14

The variable you measure

Question 15

What is an Independent variable?

Answer 15

The variable that changes

e.g The amount of water pouring down on the plant

Question 16

How do you measure tangents?

Answer 16

Watch videos on the Revision checklist or on Youtube and practise yourself in your own time or through past papers

Question 17

What is a tangent?

Answer 17

A tangent is a straight line which touches the curve at the point of interest only. They measure reactions at one single point, and not the rate of the whole reaction.