Chapter 9,10 and 11?

Question 1

Explain, in terms of particles, why a higher temperature causes a faster rate of reaction. (3)

Answer 1

The particles’ energy/speed increases

collide more frequently

collide more energetically / succesfully

Question 2

Simplest ionic equation which represents a neutralisation reaction (1)

Answer 2

H+ + OH- -> H20

Question 3

What is one way to increase the rate of reaction (1)

Answer 3

increase the temperature / use smaller pieces of metal / use more metal / increase the surface area of the metal / add a catalyst / increase the concentration / strength of the acid

Question 4

Where is hydrogen obtained (1)

Answer 4

From a natural gas / methane

Question 5

What happens to the unreacted nitrogen and hydrogen (1)

Answer 5

They get recycled

Question 6

What is meant by ‘equilibrium’ (1)

Answer 6

The forward reaction = backwards /reverse reaction

Question 7

Explain, as fully as you can, why:
- the yield of ammonia decreases with increase in temperature,
- despite this fact, a comparatively high temperature of 450C is used for the industrial process,
- iron powder is added to the reactor (4)

Answer 7

• Reaction makes products -> reactants
• at low temperatures the rate of reaction is slow.
• higher temperature is used for economic reasons so ammonia is produced at a higher rate
• iron powder is a catalyst/ speeds up the reaction.

Question 8

In industry, enzymes are used in both batch processes and continuous processes. Give one reason why continuous processes are usually more profitable than batch processes.(1)

Answer 8

labour costs lower / enzymes cost lower

Question 9

What effect does increasing the pressure have on the percentage of ammonia made? N2(g) + 3H2 (g) -> 2NH3 (its a reversible reaction) (2)

Answer 9

increases % / amount of ammonia

favours the forward reaction

Question 10

A lower temperature of 100c gives high percentages of ammonia at most pressures. Why is this temperature not used in the Haber process? (1)

Answer 10

reaction(s) would be too slow

Question 11

Describe and explain the effect of an increase in the temperature on the reaction between nitrogen and hydrogen in the Haber process. (3)

Answer 11

• rate increased
• decreases % / amount of ammonia
• the forward reaction is exothermic
• the backward reaction is endothermic
• backward reaction favoured / forward reaction not favoured
• yield / amount of nitrogen and hydrogen increased
• the relative amount (yield) of ammonia decreases as the equilibrium is changed
• the relative amount (yield of nitrogen and hydrogen increases as the equilibrium is changed.

Question 12

what is meant by an exothermic reaction (1)

Answer 12

(a reaction that) transfers energy to the surroundings

Question 13

what is meant by ‘activation energy’

Answer 13

minimum amount of energy (that) particles must have to react

Question 14

CH4 +H20 -> CO + 3H2
Explain why the reaction is endothermic. refer to bonds broken and bonds formed in your answer. (3)

Answer 14

• energy must be supplied to break bonds.
• (and) energy is released when bonds are formed
• (so) the energy needed to break existing bonds is greater than the energy released forming (new) bonds

Question 15

C2H4(g) +H20 = C2H50H(g) [reaction is reversible]
The scientist calculated that 1.0kg of ethene should produce 1.6kg of ethanol. At the end of the experiment the scientist collected 80g of ethanol. The scientist also noticed an unexpected white solid in the container. (3)

Answer 15

• the reaction is reversible
• some of the ethanol/gas may be lost
• (some of the ethene) has reacted in a different way to expected (to produce a white solid)

Question 16

CH4(g) + H20(g) -> CO(g) +3H2(g) [the reaction is reversible]
explain the effect on the equilibrium position of increasing the pressure. (2)

Answer 16

• the equilibrium position shifts to the left hand side
• because there are fewer molecules of gas on the left hand side.

Question 17

https://ibb.co/BcsRdBD
Explain the effect on the equilibrium position of increasing the temperature. (3)

Answer 17

• The percentage yield of product / hydrogen increases as temperature increases.
• forward reaction is endothermic
  OR backward reaction is exothermic
• so equilibrium position shifts to right hand side

Question 18

The position of the equilibrium depends on the initial concentrations of the reactants. Give two other conditions that can affect the position of the equilibrium (2)

Answer 18

• pressure
• temperature

Question 19

Explain why the rate of the forward reaction decreases with time. Refer to particles and collisions in your answer.

Answer 19

• number of reactant particles in the same volume decreases
• (so) frequency of collisions decreases.

Question 20

Compare the rates of the forward and backward reactions at equilibrium.

Answer 20

The rates of forward and backward reactions are the same