Equilibrium

Question 0

What are the uses of ammonia? (2)

Answer 0

In the ostwold process to make nitric acid
To react ammonia with nitric acid for ammonium nitrate - v good fertiliser as there are 2 types of nitrogen - to make plant proteins

Question 1

What is the purpose of the haber process?

Answer 1

To produce ammonia

Question 2

What is the equation for the haber process?

Answer 2

Nitrogen + hydrogen —> ammonia (+ heat)

Question 3

Where is nitrogen obtained from in the haber process?

Answer 3

From air (78%)

Question 4

Where is hydrogen obtained from?

Answer 4

From natural gas/cracking a hydrocarbon

Question 5

What are the conditions for the haber process? (3)

Answer 5

Pressure - 200 atms
Temperature - 450c
Catalyst - iron

Question 6

Is the forward reaction in the haber process exo/endothermic?

Answer 6

Exothermic

Question 7

What is the compromise in the haber process and why?

Answer 7

The temperature as we want low temp for it to shift right but we have it at 450c to speed up the reaction

Question 8

What’s the definition of a reversible reaction?

Answer 8

A chemical change when products can be converted back to original reactants under suitable conditions in a closed vessel

Question 9

When is dynamic equilibrium reached?

Answer 9

When it’s in a closed vessel and overall effect is nothing

Question 10

What does position of equilibrium depend on?

Answer 10

Temperature - more products and less reactants

Pressure

Question 11

What’s the difference between higher and lower pressure in equilibrium?

Answer 11

Higher pressure produces less molecules- shifts right

Lower pressure produces more molecules of gas- shifts left

Question 12

What happens if a change is imposed on a system? (Equilibrium)

Answer 12

The system will change to minimise the enforced change to re-establish equilibrium

Question 13

What is an example of a reversible reaction?

Answer 13

Thermal decomposition of ammonium chloride
when heated and broken down (FORWARD)

BACKWARD- cool it and it’s a solid

Question 14

What is the purpose of the contact process?

Answer 14

To produce sulphuric acid

Question 15

What are the uses of sulphuric acid? (3)

Answer 15

For phosphate fertilisers (plant growth)
Detergents (cleaning)
Paints (used to make titanium dioxide which has a white pigment)

Question 16

What are the conditions of the contact process? (3)

Answer 16

Pressure - 2 atms
Temperature - 450c
Catalyst - vanadium oxide

Question 17

What’s the first step in the contact process?

Answer 17

Burn sulphur in air

Sulphur + oxygen —> sulphur dioxide

Question 18

What is the second step in the contact process?

Answer 18

Sulphur is oxidised

Sulphur dioxide + oxygen —> sulphur trioxide

Question 19

What is the third step in the contact process?

Answer 19

Sulphur trioxide is dissolved in sulphuric acid

Sulphur trioxide + sulphuric acid —> oleum

Question 20

What is the forth step in the contact process?

Answer 20

Oleum diluted with measured water

Oleum + water —> concentrated sulphuric acid

Question 21

Which step in the contact process is exothermic?

Answer 21

Step 2 (sulphur dioxide is oxidised)

Question 22

Describe the effect a decrease of pressure has on rate of reaction and why?

Answer 22

Decreases rate

Fewer molecules present per unit volume

Fewer successful collisions per unit time

Question 23

Describe the effect a decrease of pressure has on the position of equilibrium and why?

Answer 23

Shifts right

More moles of gas on the right than left

Question 24

What effect on yield does increase of temperate have?

Answer 24

Decreases - direction moves backwards

Question 25

What effect on yield does an addition of catalysis have on a reversible reaction?

Answer 25

Unchanged as it speeds up backward reaction too