AS CHEMISTRY
NITROGEN AND SULFUR
1
Draw a dot-cross diagram to show the bonding in a molecule of nitrogen, N2. Use your
data booklet to find the bond energy of the triple bond. Hence explain why nitrogen is
very unreactive.
2
Draw a dot-cross diagram to show the bonding in (i) an ammonia molecule, NH3, (ii) the
ammonium ion, NH4+. Explain how the ammonium ion forms from an ammonia
molecule.
3
A test-tube experiment: Put a little solid ammonium chloride into a clean tube. Add
approx 1 cm3 of dil sodium hydroxide solution. Carefully bring to the boil (WEAR EYE
PROTECTION). Test the gas evolved with damp red litmus paper. Write an equation
for the reaction that has occurred.
4
Revise the Haber Process for the manufacture of ammonia (textbook, p 133-5).
(i)
(ii)
(iii)
(iv)
(v)
Write the equation for the reaction involved
Explain why a high pressure is used (250 atmospheres)
Explain why a moderately high temperature is used (450C)
Explain why an iron catalyst is used
List the important uses of ammonia
5
What is eutrophication? (Look at your Biology notes!) Explain how it is caused by the
uncontrolled use of fertilisers. See p 261.
6
Revise textbook, pages 189-191.
(i)
Explain how oxides of nitrogen are formed in the engines of motor vehicles.
(ii)
Explain why these oxides are harmful.
(iii)
Explain how these pollutants are removed by catalytic converters.
(iv)
Explain how sulfur dioxide gets into the air and why it is harmful
7
Describe the main environmental consequences of acid rain
8
Revise the Contact Process for the manufacture of sulfuric acid (textbook p 135-6)
(i)
Write the equation for the conversion of sulfur dioxide to sulfur trioxide
(ii)
Explain why a moderately high temperature is used (450C)
(iii)
Explain why a catalyst of vanadium(V)oxide is used
(iv)
Explain why the sulfur trioxide produced is dissolved in conc sulfuric acid, rather
than water.
(v)
List the main uses of sulfuric acid
9
How is sulfur dioxide used in food preservation? (Textbook p264)