Question 1

What does the rate of a chemical reaction tell you?

Accepted Answer

How fast reactants turn into products

Answer

How fast products turn into reactants in an irreversible reaction

Question 2

Why is the rate of a reaction important in industry?

Accepted Answer

The quicker the reaction the cheaper it is as it is quick to make the product and make profit from it

Answer

The quicker the reaction the cheaper it is as it is slow to make the product and make profit from it

Question 3

How can you measure the rate of a chemical reaction?

Accepted Answer

How quick the products of the reaction are made

Answer

How quick the products of the reaction are used

Question 4

How can you measure the rate of a chemical reaction?

Accepted Answer

How quick the reactants are used up as they make products

Answer

How quick the reactants are made as they make products

Question 5

How do you calculate the rate of a reaction at a specific time?

Accepted Answer

draw a tangent to the curve at that time, work out the gradient

Answer

amount of reactant/product / time of reaction

Question 6

How do you calculate the mean rate of a reaction?

Accepted Answer

amount of reactant/product / time of reaction

Answer

draw a tangent to the curve at that time, work out the gradient

Question 7

What does the collision theory state?

Accepted Answer

In order for a reaction to occur, the particles of reactants must collide with enough energy to cause a reaction to take place.

Answer

In order for a reaction to occur, the particles of reactants must collide with enough speed  to cause a reaction to take place.

Question 8

What is the minimum energy required for a collision to lead to a reaction?

Accepted Answer

Activation energy

Answer

Alternation energy

Question 9

When are reactions more likely to happen?

Accepted Answer

the frequency of collision increases, the particles have more energy

Answer

the frequency of collision decreases, the particles have more energy

Question 10

How does surface area affect reaction rate?

Accepted Answer

Increasing surface area to volume ratio increases the frequency of collisions between reacting particles as more of them are exposed to collisions.

Answer

Increasing surface area to volume ratio increases the frequency of collisions between reacting particles as less of them are exposed to collisions.

Question 11

How does increasing the temperature of a reaction mixture increase the rate of a reaction?

Accepted Answer

Particles collide 1) more frequency and 2) more energetically. A higher proportion of particles would have energy greater than the activation energy.

Answer

Particles collide more frequency and more energetically due to the increased kinetic energy of the reacting particles. A smaller proportion of particles would have energy greater than the activation energy.

Question 12

How does increasing the concentration of solutions  increase the rate of reaction?

Accepted Answer

It increases the frequency of collisions between particles as there are more reacting particles moving around in the same volume of solution.

Answer

It increases the frequency of collisions between particles as there are less reacting particles moving around in the same volume of solution.

Question 13

How does increasing the pressure of reacting gases increase the rate of reaction?

Accepted Answer

The number of collisions between reacting particles is increased as the gas particles are squashed closer together. This leads to a higher chance of successful collisions.

Answer

The number of collisions between reacting particles is increased as the gas particles are squashed closer together. This leads to a lower chance of successful collisions.

Question 14

What is a catalyst? Pick the best definition

Accepted Answer

It is a substance which increases the rate of a reaction by providing an alternative pathway for the reaction to occur with a lower activation energy. It is not used up during a reaction.

Answer

A substance which speeds up reactions.

Answer

It is a substance which increases the rate of a reaction by providing an alternative pathway for the reaction to occur with a lower activation energy. It is used up during a reaction.

Question 15

Why are catalysts used in industry?

Accepted Answer

They save money and help the environment as lower temperatures and pressures are needed for a reaction to happen. High temperatures use more fossil fuels.

Answer

They save money and help the environment as higher temperatures and pressures are needed for a reaction to happen. High temperatures use more fossil fuels.

Question 16

Can a catalyst be used for all reactions?

Accepted Answer

No, different catalysts are needed for different reactions.

Answer

Yes, catalysts have the ability to speed up all types of reactions.

Question 17

What do two half arrows facing different directions mean?

Accepted Answer

reversible reaction

Answer

irreversible reaction

Question 18

What is a forward reaction?

Accepted Answer

Reactants reacting to form products

Answer

Products reacting to form reactants

Question 19

In reversible reactions, if the forward one is exothermic, what is the backward reaction?

Accepted Answer

Endothermic reaction

Answer

Exothermic reaction

Question 20

In reversible reactions, if the forward one is endothermic, what is the backward reaction?

Accepted Answer

Exothermic reaction

Answer

Endothermic reaction

Question 21

In reversible reactions, the energy transferred from the surroundings to the reaction is

Accepted Answer

equal to the energy transferred from the reaction to the surroundings when the reaction goes in the opposite direction

Answer

greater than the energy transferred from the reaction to the surroundings when the reaction goes in the opposite direction

Question 22

Describe how a reaction mixture reaches dynamic equilibrium.

Accepted Answer

The forward reaction occurs fast as only reactants are present at the start. As products are produced, the rate of the forward reaction decreases (reactants are being used up) and the rate of the backward reaction is increasing. Eventually the rate of the forward and backward reactions are the same.

Answer

The forward reaction occurs fast as only reactants are present at the start. As products are produced, the rate of the forward reaction increases (reactants are being used up) and the rate of the backward reaction is increasing. Eventually the rate of the forward and backward reactions are the same.

Question 23

What is dynamic equilibrium?

Accepted Answer

The rate of forward reaction equals the rate of the backward reaction in a closed system.

Answer

The rate of forward reaction equals the rate of the backward reaction in an open system.

Question 24

What is Le Chatelier's Principle?

Accepted Answer

If there is a change to the conditions of the reaction mixture at equilibrium, the position of the equilibrium will shift to oppose the change.

Answer

If there is a change to the conditions of the reaction mixture at equilibrium, the position of the equilibrium will shift to further the change.

Question 25

In a reaction mixture at equilibrium, if the concentration of the products is increased

Accepted Answer

the equilibrium position will shift to the left to favour the backward reaction and make sure the extra products are used up.

Answer

the equilibrium position will shift to the right to favour the forward reaction and make sure the extra reactants are used up.

Question 26

In a reaction mixture at equilibrium, if the concentration of the reactants is increased

Accepted Answer

the equilibrium position will shift to the right to favour the forward reaction and make sure the extra reactants are used up.

Answer

the equilibrium position will shift to the left to favour the backward reaction and make sure the extra reactants are used up.

Question 27

In a reaction mixture  of gases at equilibrium, if the pressure is increased

Accepted Answer

It will shift the equilibrium position to favour the formation of the side which produces less moles/molecules to decrease the pressure

Answer

It will shift the equilibrium position to favour the formation of the side which produces more moles/molecules to increase the pressure

Question 28

In a reaction mixture at equilibrium, if the temperature is increased

Accepted Answer

It will favour the endothermic reaction so that the temperature drops again.

Answer

It will favour the exothermic  reaction so that the temperature rises again.

Question 29