Rates Of Reaction

Question 1

The rate of a chemical reaction depends on:

Answer 1

The collision frequency of reacting particles (the more collisions there are the faster the react is)

The energy transferred during a collision . Particles have to collide with enough energy for the collision to be successful. (a successful collision is a collision that ends in the particles reacting to form products)

Question 2

What is activation energy?

Answer 2

The minimum amount of energy that particles need to react

Question 3

Factors that increase the rate of the reaction:

Answer 3

1) temperature
2) the concentration of a solution or the pressure of a gas
3) surface area – this changes depending on the size of the lumps of a solid
4) the presence of a catalyst

Question 4

What is a catalyst?

Answer 4

A catalyst is a substance that speeds up a reaction without being used up in the reaction itself . So is not part of the overall reaction equation

Question 5

Give an example of a biological catalyst

Answer 5

Enzymes- catalyse reactions and living things

Question 6

Measuring the rate of reaction practical

Question 7

Rate experiments practical

Question 8

How do you calculate the main reaction rate from a graph?

Answer 8

Change in Y over (divided by) change in X

Question 9

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

Answer 9

Draw a tangent on the point you what to know the reaction rate for and work out it’s gradient (change in Y over (divided by) change in X)

Question 10

What is the symbol to show a reaction is reversible

Answer 10

⇌

Question 11

Write the reversible reaction equation:

Answer 11

A+B ⇌ C+D

Question 12

What is equilibrium?

Answer 12

When the forwards reaction is going at the exact same rate as the backwards one

Question 13

As reactants react, their ——— fall- so the forward reaction will —— ——. But as more and more product are made and their ——— rise, the backwards reaction will —— —-.

Answer 13

concentration
Slow down
Concentration
Speed up

Question 14

What is a dynamic equilibrium?

Answer 14

Both reactions are still happening, but there is no overall effect-meaning the concentration of reactants and products have reached a balance and won’t change.

Question 15

What is a ‘closed system’ ?
What does this have to do with equilibrium?

Answer 15

A closed system just means that none of the reactants or products can escape and nothing else can get in

Equilibrium is only reached if the reversible reaction takes place in a closed system

Question 16

What is the position of equilibrium depend on? Name the conditions:

Answer 16

1) temperature
2) the pressure (this only affects equilibria involving gases)
3) The concentration of the reactants and product

Question 17

Is the concentration always equal in a reversible reaction?

Answer 17

No.

If the equilibrium lies to the right, the concentration of the product is greater than that of the reactant

If the equilibrium lies to the left the concentration of reactants is greater than that of the product .

Question 18

What does anhydrous mean?

Answer 18

Without water

Question 19

What does hydrated mean?

Answer 19

With water

Question 20

What is the Chatelier’s principle?

Answer 20

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

It can be used to predict the effects of any changes you make to a reaction system

Question 21

If you decrease the temperature, the equilibrium will move in the ——— direction to produce more heat.

Answer 21

Exothermic

(Meaning you’ll get more products for the exothermic reaction and fewer products for the endothermic reaction)

Question 22

If you raise the temperature, the equilibrium will move in the ———direction to try and decrease it.

Answer 22

Endothermic

(you’ll get more products for the endothermic reaction and fewer products for the exothermic reaction)

Question 23

When bonds break it is a ———reaction

Answer 23

Endothermic

Question 24

When bones form it is a——— reaction

Answer 24

Exothermic

(Strong bond formed + energy released)

Question 25

If you increase the pressure, the equilibrium tries to —— it
It moves in the direction where there are —— molecules of gas

Answer 25

Reduce
Fewer

Question 26

If you decrease the pressure that equilibrium tries to ——it
It moves in the direction where there are —— molecules of gas

Answer 26

Increase
More

Question 27

If you increase the concentration of the reactants the system tries to ——- it by making more ——

Answer 27

Decrease
Products

(if you change the concentration of either the reactants or the product the system will no longer be at equilibrium)

Question 28

If you decrease the concentration of products, the system tries to ——- it again by reducing the amount ——

Answer 28

Increase
Reactants

(if you change the concentration of either the reactants or the products the system will no longer be at equilibrium)