Standard Grade Revision
Unit 14
Q. 1 Industrially ammonia (NH3) is made by reacting together nitrogen and
hydrogen.
(a) What is the source of the
(i) nitrogen used in the process?
(ii) hydrogen used in the process/
(b) What is the name given to the industrial process used to manufacture
ammonia.
(c) What is the name of the catalyst used in the process?
(d) The yield of ammonia drops as the temperature of the reaction
increases. Explain why the reaction is carried out at temperatures of
about 500oC.
(a) (i) Nitrogen comes from the air.
(ii) Hydrogen comes from water or methane.
(b) Haber Process.
(c) Iron.
Standard Grade Chemistry
(d) Reaction is too slow at lower temperatures.
Unit 14 Revision
Q2. Fritz was investigation the properties of ammonia.
(a)
Why did the water rise up the test tube when the stopper was removed.
(b)
When the stopper was removed the reading on the pH meter changed.
Suggest what the new reading would been.
(a) Ammonia is very soluble in water.
(b) pH value greater than 7 (ammonia is an alkaline gas).
Standard Grade Chemistry
Q3.
Ammonium nitrate is made by the reaction of ammonia with nitric acid. Ammonia is made
by passing a mixture of nitrogen and hydrogen through a catalyst chamber.
Unreacted
nitrogen and hydrogen are removed and returned to the catalyst chamber. The ammonia
gas then enters a reaction vessel in which ammonium nitrate is produced.
Copy this flow chart and use the information above to complete it.
hydrogen
Unreacted
nitrogen and
ammonia
ammonia
Ammonium
nitrate
Standard Grade Chemistry
Unit 14 Revision.
Q4. (a) How are plants such as peas and clover able to convert nitrogen from the air into
nitrogen compounds?
(b) Nitrogen and oxygen in the air can be converted into oxides of nitrogen
What provides the energy for this process?
(c) Plants need phosphorus to grow.
Suggest why calcium phosphate is not suitable as a fertiliser.
You may wish to use page 5 of the data booklet.
(c) Phosphorus is one of the essential elements supplied by fertilisers.
Name the two other essential elements.
(a) These plants have nitrifying bacteria in root nodules. The bacteria
can convert nitrogen in the air into nitrogen compounds in the soil.
(b) The energy from a lightning discharge.
(c) Calcium phosphate is insoluble. Plants need fertilisers in soluble
form.
(d) Potassium and nitrogen.
Standard Grade Chemistry
Unit 14 Revision.
Q5.
(a) The flow diagram shows how ammonia is converted to nitric acid.
ammonia
X
reactor
nitrogen dioxide
air
absorber
air
nitric acid
(HNO3)
(i) Name the industrial process used to manufacture nitric acid.
(ii) Name the catalyst used in the reactor.
( iii) Name substance X.
(b) Ammonia and nitric acid react to form ammonium nitrate.
(i) Explain why ammonia is able to react with nitric acid.
(ii) Give a use for ammonium nitrate.
(c) Calculate the percentage of nitrogen in ammonium nitrate (NH4NO3).
Standard Grade Chemistry
(a)
(i) Ostwald Process.
(ii) Platinum
(iii) water
(b)
(i) Ammonia is an alkaline gas. (ii) Nitrogen containing fertiliser.
(c)
35%
Q 6. The names of several compounds are shown in the box.
potassium nitrate
sodium hydroxide
lithium sulphate
aluminium chloride
ammonium chloride
calcium phosphate
(a) Identify the two compounds which can be used as fertilisers.
(b) Identify the two compounds which react together to produce ammonia.
(a)
Potassium nitrate and ammonium chloride.
(b)
Sodium hydroxide and ammonium chloride.
Q. Nitrogen forms many useful compounds.
Compound
Formula
Y
(NH4) 3PO4
potassium nitrate
urea
KNO3
CO(NH2) 2
(a) (i) Name compound Y.
(ii) Compound Y can be used as a fertiliser.
(a) Ammonium phosphate.
(b) To increase crop yields.
Why are fertilisers added to the soil?
(b) Which acid is used to make potassium nitrate?
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(c) Nitric acid.
Unit 14 Revision.
Q7.
( a) The flow chart shows some processes which take place in an industrial
chemical complex.
water
methane
air
ammonia plant
phosphoric acid plant
fertiliser plant
(a) Air and water are used as raw materials because they contain the elements
needed to make ammonia.
Suggest one other reason why they are used as raw materials.
(b) Which reactant for the ammonia plant must be produced in the reaction
between methane and water?
(c) Name the salt formed in the fertiliser plant.
Standard Grade Chemistry
(a)
They are cheap.
(b)
Hydrogen.
(c) Ammonium phosphate.
Unit 14 Revision.
Q8.
The reaction for the production of ammonia in the Haber Process is shown below.
N2 + 3H2  2 NH3
(a) A Haber process plant converts 1400 tonnes of nitrogen into ammonia.
Calculate the mass of ammonia produced.
(b) How is the ammonia produced removed from the nitrogen and hydrogen?
(c) Increasing the pressure gives a bigger yield of ammonia.
Most Haber Process plants operate about about 150 to 200 atmospheres pressure.
Suggest a reason why the do not operate at much higher pressures.
(a)
1700 tonnes.
(b)
The ammonia is liquefied to remove it from the gaseous nitrogen and
hydrogen.
(c)
Much higher pressures are not used as this would raise the cost of the
plant used to make ammonia to too high a level.