Rates of Reaction - C8

Question 1

What is the equation for rate of reaction

Answer 1

= Amount of reactant used or product formed / Time

Question 2

What units are used for rate of reaction

Answer 2

g/s and cm3/s

Question 3

What is rate of reaction

Answer 3

It is a measure of the change in a reaction per unit time

Question 4

How do you measure the rate at a certain point of a graph

Answer 4

You draw a tangent off that point

Question 5

What is activation energy

Answer 5

It is the minimum amount of energy the particles need to react together

Question 6

How can rate of reaction be increased

Answer 6

Increasing the frequency of collisions
Increasing the energy of collisions
Lowering the activation energy

Question 7

What factors affect rate of reaction

Answer 7

Temperature
Catalyst
Surface Area
Concentration

Question 8

Why does temperature affect rate of reaction

Answer 8

It gives particles more energy causing them to go faster
This causes more frequent collisions
Collisions have more energy

Question 9

What is concentration

Answer 9

A measure of the number of particles of a substance in a certain volume

Question 10

Why does concentration affect rate of reaction

Answer 10

More particles, so more frequent collisions

Question 11

What is a catalyst

Answer 11

It is a substance that speeds up chemical reactions without being used up
This works by providing an alternative reaction pathway which has a lower activation energy

Question 12

Why does catalysts affect the rate of reaction

Answer 12

Because it lowers the activation energy for the reaction

This means that particles can react even with moderate amounts of energy

Question 13

Why does Surface Area affect rate of reaction

Answer 13

More reactant is exposed so more frequent collisions

Question 14

What method can you use for surface area

Answer 14

Loss in mass method

Question 15

What method can you use for temperature

Answer 15

The cross at the bottom of the flask method

Question 16

What method can you use for concentration

Answer 16

Gas syringe method

Question 17

What is a reversible reaction

Answer 17

It is a reaction which once completed can react backwards to form the original reactants

Question 18

If the forward reaction is endothermic, what is the reverse reaction

Answer 18

exothermic

Question 19

What is a salt

Answer 19

A compound formed when hydrogen is replaced by a metal

Question 20

What is water of crystallsation

Answer 20

It is water molecules contained in crystalline lattice

Question 21

What is a hydrated salt

Answer 21

It is a salt with water of crystalline

Question 22

What is a anhydrous salt

Answer 22

It is a salt where water of crystalline is not present

Question 23

What is dynamic equilibrium

Answer 23

It is when the rate of the forward reaction is the same as the rate of the backward reaction in a closed system

Question 24

What is Le Chatelier’s Principle

Answer 24

That when a change in condition is introduced to a system at equilibrium, the position of the equilibrium shifts to cancel out the change

Question 25

How does changing the concentration in equilibrium effect the equilibrium

Answer 25

When a substance is added to the left hand side, the equilibrium shifts to the right

Question 26

How does changing the temperature in equilibrium effect the equilibrium

Answer 26

When the temperature is increased the equilibrium shifts to the side that the endothermic reaction is going When the temperature is decreased the equilibrium shifts to the side that the exothermic reaction is going

Question 27

How does changing the pressure in equilibrium effect the equilibrium

Answer 27

When the pressure is increased the equilibrium shifts to the side with less moles When the pressure is decreased the equilibrium shifts to the side with more moles

Question 28

What is the Haber process

Answer 28

It is the process of making ammonia from nitrogen and hydrogen The forward reaction is exothermic

Question 29

Where does the nitrogen come from for the Haber process

Answer 29

It comes from the air and is separated

Question 30

Where does the hydrogen come from for the Haber process

Answer 30

It comes from methane or other natural gases

Question 31

How does the Haber process work

Answer 31

1. Gas containing hydrogen and nitrogen is compressed to a pressure of 200 atm and heated to 450 degrees - This is to increase the rate of reaction 2. The mixture then goes into the reaction vessel containing a iron catalyst where an equilibrium is formed - This is to increase the rate 3. The mixture is then cooled and the Ammonia liquefies and is separated 4. Unreacted nitrogen and hydrogen and fed back into the system

Question 32

What conditions is the Haber process carried out in

Answer 32

High Pressure - Increase the rate of reaction and shift the equilibrium to the right Quite High Temperature - Increases the rate of reaction but shifts the equilibrium to the left which reduces the yield