THE RATE AND EXTENT OF CHEMICAL CHANGE

Question 1

What is the rate of a chemical reaction?

Answer 1

How fast the reactants are being changed into products

Question 2

What effects the rate of reaction?

Answer 2

Temperature
Concentration/pressure
Surface area
And/or catalyst

Question 3

How do collisions affect the rate of reaction?

Answer 3

The more collisions there are the faster the rate of reaction (you can do this by increasing temp)

Question 4

What is the activation energy?

Answer 4

The minimum amount of energy needed to react (and break bonds)

Question 5

How does temperature affect the rate of reaction?

Answer 5

Increasing temp means particles move faster so can collide more frequently with more energy (more collisions will have enough energy to create reaction)

Question 6

How does concentration or pressure affect the rate of reaction?

Answer 6

More concentrated solution then more particles colliding in the same volume
When pressure of a gas is increased then the same number of particles occupy a smaller space
This makes collisions more frequent

Question 7

How does surface area affect the rate of reaction?

Answer 7

Increasing surface area to volume ratio means that the particles will have more area to work on but the same volume so collisions are more frequent

Question 8

How does the presence of a catalyst affect the rate of reaction?

Answer 8

Catalysts decrease the activation energy by providing and alternative reaction pathway with a lower activation energy

Question 9

How do you measure the rate of a reaction (equation)?

Answer 9

Amount of reactant used up/product formed divided by time

Question 10

What are different ways you can measure the rate of a reaction?

Answer 10

Precipitation
Colour change
Change in mass
Volume of gas given off

Question 11

How do you find the mean rate of reaction from a graph?

Answer 11

Overall change in y divided by overall change in x

Question 12

How do you find the rate of reaction at a particular point?

Answer 12

Draw a tangent then calculate gradient

Question 13

How can equilibrium only be reached?

Answer 13

If the reaction is taking place in a closed system

Question 14

What is equilibrium?

Answer 14

When both reactions are happening but there is no overall effect
The concentrations of the reactants and products have reached a balance
The forward and back reactions are happening at the same rate

Question 15

What happens when the equilibrium lies to the right?

Answer 15

The concentration of products is greater

Question 16

What happens when the equilibrium lies to the left?

Answer 16

The concentration of the reactants is greater

Question 17

How do exothermic and endothermic reversible reactions work?

Answer 17

The energy transferred from the surroundings by the endothermic reaction is equal to the energy transferred to the surroundings during the exothermic reaction

Question 18

What is le chateliers principle?

Answer 18

The idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract that change

Question 19

What happens if you increase the temperature in exothermic reactions?

Answer 19

The yield will decrease

Question 20

What happens if you increase the temperature in endothermic reactions?

Answer 20

The yield will increase

Question 21

What happens when you increase the pressure in a reversible reaction?

Answer 21

Equilibrium will move in the direction where there is fewer moles

Question 22

What happens when you decrease the pressure in a reversible reaction?

Answer 22

Equilibrium will move in the direction where there is more moles

Question 23

What happens when you increase the concentration of the reactants in a reversible reaction?

Answer 23

The products will increase

Question 24

What happens when you decrease the concentration of the products in a reversible reaction?

Answer 24

The reactants will decrease