Ch - 9 (Reversible Reactions)

Question 1

What happens in a reversible reaction?

Answer 1

Reaction can go in both directions.

To the right (forms the products)
To the left (forms the reactants)

Question 2

What does the Haber process help in the production of?

Answer 2

Ammonia, hydrogen and nitrogen

Question 3

What colour do anhydrous blue cobalt (II) chloride crystals turn into when water is added.

Answer 3

pink

Question 4

What colour do cobalt crystals turn into when heated?

Answer 4

Blue (water of crystallisation is lost)

Question 5

What are the chemical tests commonly used to detect the presence of water?

Answer 5

CoCl2 (Copper chloride)
CuSO4 (Copper sulfate)

Question 6

What happens in the concept of equilibrium?

Answer 6

The rate of forward reaction equals the rate of the reverse reaction.

Question 7

How is the molecules affecting the concept of equilibrium?

Answer 7

Dynamic, molecules are changing into each other by chemical reactions constantly changing

Question 8

What happens to the concentration in equilibrium?

Answer 8

Remains constant in a closed system

Question 9

What happens to the position of equilibrium when concentration of reactant increases?

Answer 9

Shifts to the left

Question 10

What happens to the position of equilibrium when concentration of product increases?

Answer 10

Shifts to the right

Question 11

What does the Le Chatelier principle state?

Answer 11

When a change is made to the conditions of a system at equilibrium, the system automatically moves to oppose the change.

Question 12

What is the Le Chatelier Principle used to predict?

Answer 12

Predicts the chances to the position of equilibrium when there ate changes in temperature, pressure and concentration.

Question 13

What is the effect on equilibrium when temperature is increased?

Answer 13

Moves in the endothermic direction to reverse the change.

Question 14

What is the effect on equilibrium when temperature is decreased?

Answer 14

Equilibrium moves in the exothermic direction to reverse the change.

Question 15

What is the effect of an increase in pressure on equilibrium?

Answer 15

shifts in the direction that produces the smaller number of molecules of gas to decrease the pressure again.

Question 16

What is the effect of an decrease in pressure on equilibrium?

Answer 16

equilibrium shifts in the direction that produces large number of molecules of gas to increase the pressure.

Question 17

What is the effect of an increase in concentration on Equilibrium?

Answer 17

Shifts to the right to reduce the effcf of increase in conc. of a reactant

Question 18

What is the effect of a decrease in concentration on Equilibrium?

Answer 18

equilibrium shifts to the left to reduce the effect of a decrease in reactant

Question 19

What is the effect of a catalyst on Equilibrium?

Answer 19

it does not affect the position of equilibrium but it does increase the rate at which equilibrium is reached.

Question 20

Why does a catalyst not have an effect on equilibrium?

Answer 20

• Catalyst increases the rate of both forward and backward reactions by the same amount.
• Concentration of reactant and products is the same.

Question 21

Define Haber process.

Answer 21

The manufacturing of ammonia in an exothermic reaction.

Question 22

What are the stages of Haber process?

Answer 22

Stage 1: H2 and N2 are obtained from natural gas and the air respectively and are pumped into the compressor through pipe.

Stage 2: Gasses are compressed to about 200 atmospheres inside the compressor.

Stage 3: Pressurized gases are pumped into a tank

Stage 4: Unreacted H2 & N2 and the product ammonia pass through the cooling tank. The ammonia is liquefied and removed to pressurize storage vessels.

Stage 5: The unreacted H2 and N2 gases are recycles back into the system and it starts over again.

Question 23

What happens to yield as pressure increases on x - axis ?

Answer 23

Yield increases at any temperature.

Question 24

What happens to yield as temperatures decreases on y - axis ?

Answer 24

the yield increases

Question 25

What’s re the economic conditions in the Haber peocess?

Answer 25

• Readily available and inexpensive to purify
• Nitrogen: From the air
• Hydrogen: From natural gas

Question 26

What are the conditions needed for Haber process?

a) Temperature
b) Pressure
c) catalyst

Answer 26

a) Temperature - 450°C
b) Pressure - 200atm
c) catalyst - iron

Question 27

What will happen at a higher temperature for Haber process?

Answer 27

• Favour the reverse reaction as it is endothermic (takes in heat) so a higher yield of reactants would be made.

Question 28

What will happen at a lower temperature for Haber process?

Answer 28

It favors the forward reaction as it is exothermic (releases heat) so a higher yield of products would be made.

Question 29

What will happen at Lower pressure for the Haber process?

Answer 29

• Favor the reverse reaction, the system will try to increase the pressure by creating more molecules, so a higher yield of reactant will be made

Question 30

What will happen at higher pressure for the Haber process?

Answer 30

Favor the forward reaction as it will try to decrease the pressure by creating less molecules, so a higher yield of products will be made.

Question 31

What will happen for catalyst iron in Haber process?

Answer 31

It allows an acceptable yield to be achieved at a lower temperature by lowering the activation energy required

Question 32

What is a contact process?

Answer 32

• sulfuric acid synthesized by the contact process.
• concentrated sulfuric acid is used in car batteries, making fertilizers, soaps and detergents

Question 33

What are the stages of contact process?

Answer 33

Stage 1: Production of sulfur dioxide, with by burning sulfur to oxidise the sulfur, or roasting sulfide ores.

Stage 2: the oxidation of sulfur dioxide to sulfur trioxide using vanadium (V) oxide, V2O5, catalyst.

O2 is obtained from the air.

Question 34

What are the conditions needed for Haber process?

a) Temperature
b) Pressure
c) catalyst

Answer 34

a) Temperature - 450°C
b) Pressure - 200kPa
c) catalyst - vanadium (V) oxide

Question 35

Why is increasing the temperature Good in contact process?

Answer 35

• Forward reaction is exothermic, it shifts the equilibrium to the left of the reactants
• higher temperature, lowers the yield of sulfur trioxide

Question 36

Why is increasing the pressure in contact process Good?

Answer 36

• Shifts the equilibrium to the right, in direction of a smaller no. molecules
• equilibrium lies far to the right

Question 37

Why the contact process carried just above atmospheric pressure?

Answer 37

• High pressures can be dangerous and very expensive equipment is needed
• A higher pressure causes the sulfur dioxide to liquefy