Reversible Reactions

Question 1

Equation for Haber process reaction

Reversible reaction

Answer 1

N2 (g) + 3H2 (g) 2NH3 (g)

Question 2

What is a reversible reaction and what is the name for when the reaction appears to stop?

Answer 2

Both forward and backward reactions happen at same rate and at same time. The Chemical Equilibrium is when the reaction appears to stop

Question 3

• Conditions to maximise yield of ammonia?
• Why are there problems meeting these conditions?
• How can we counteract problem?

Answer 3

-High pressures, low temperatures are needed.
-Low temp = slow rate of reaction
High pressures = too expensive and dangerous
-Add Iron catalyst

Question 4

Compromise conditions for Haber process

Answer 4

·Temperature:
350 - 450 degrees Celsius
·Pressure:
150 - 200 atmospheres

Question 5

Ammonia test with damp red and blue litmus paper

Answer 5

·Blue= stays blue shows its not acidic
·Red= turns blue shows its alkaline

Question 6

Stages of production of Sulphuric acid (Contact process)

Answer 6

Stage 1:
·S (s) +O2 (g) --> SO2 (g)
Stage 2:
·Vanadium (V) oxide catalyst
·Temp 450 degrees Celsius
·Pressure 1-2 atm
·2SO2 (g) + O2 (g)  2SO3 (g)
Stage 3:
·Concentrated sulphuric acid added to sulphur trioxide
·"Fuming sulphuric acid" or "oleum"
·SO3 + H2SO4 --> H2S2O7

·H2S2O7 + H2O –> 2H2SO4

Question 7

In stage 3 of contact process, why is sulphur trioxide gas mixed with concentrated sulphuric acid?

Answer 7

If SO3 added directly to water, reaction is very exothermic and dangerous “acid mist” is formed

Question 8

What is a dehydrating agent?

Answer 8

Removes water from a substance e.g. Sulphuric acid

Question 9

Sulphuric acid + sugar

Answer 9

• Vigorous exothermic reaction
• White to black
• Bubbles of steam cause carbon to expand into a foam

Question 10

Sulphuric acid + hydrated copper (II) sulphate

Answer 10

-Blue crystals to white powder known as Anhydrous copper (II) sulphate

Question 11

Benefits of nitrogenous fertilisers to society and problems that can occur when used

Answer 11

• Add nitrogen to soil which plants use to make proteins = healthy plants that produce food quickly
• Less expensive and easier than moving crops for fields to fallow
• Increases yield in small place
• Use in places where soil has no nitrates
• Contaminate drinking water, can be carcinogenic and linked to “blue baby syndrome”
• Eutrophication

Question 12

Catalyst for oxidation of ammonia?

Answer 12

Platinum or Rhodium

Question 13

Oleum

Answer 13

H2S2O7