C2- rates of reaction

Question 1

What are the two ways to measure the rate of reaction?

Answer 1

Measure the rate at which a reactant is used up
Measure the rate at which a product is formed
The method chosen depends on the reaction being studied. Sometimes it is easier to measure the change in the amount of a reactant that has been used up; sometimes it is easier to measure the change in the amount of product that has been produced.

Question 2

How are substances measured when calculating the rate of reaction?

Answer 2

The mass of a substance - solid, liquid or gas - is measured with a balance
The volume of a gas is usually measured with a gas syringe, or sometimes an upside down measuring cylinder or burette

Question 3

What is the formula for the rate of reaction?

Answer 3

Amount of reactant used or amount of product formed divided by the time taken.

Question 4

What increases the rate of reaction?

Answer 4

The rate of a reaction increases if:

The temperature is increased
The concentration of a dissolved reactant is increased
The pressure of a reacting gas is increased
Solid reactants are broken into smaller pieces
A catalyst is used

Question 5

What needs to happen for a chemical reaction to occur?

Answer 5

For a chemical reaction to occur, the reactant particles must collide. Collisions with too little energy do not produce a reaction.The collision must have enough energy for the particles to react.

Question 6

What is activation energy?

Answer 6

The minimum energy needed for particles to react

Question 7

Why does increases the concentration of a dissolved reactant, or the pressure of a reacting gas increase the rate of reaction?

Answer 7

There are more reactant particles in the same volume
There is a greater chance of the particles colliding
The rate of reaction increases

Question 8

Why does breaking a solid reactant down into smaller pieces increase the rate of reaction?

Answer 8

Its surface area is increased
More particles are exposed to the other reactant
There is a greater chance of the particles colliding
The rate of reaction increases

Question 9

Why does increasing the temperature increase the rate of reaction?

Answer 9

The reactant particles move more quickly
More particles have the activation energy or greater
The particles collide more often, and more of the collisions result in a reaction
The rate of reaction increases

Question 10

Why does using a catalyst increase the rate of reaction?

Answer 10

Catalysts increase the rate of reaction without being used up. They do this by lowering the activation energy needed. With a catalyst, more collisions result in a reaction, so the rate of reaction increases. Different reactions need different catalysts.