Coal is a mixture of carbon compounds with a small amount of sulfur. A sample of coal is heated in the absence of air using the apparatus shown. [Figure A2.1: Diagram showing powdered coal being heated, connected to a test tube immersed in water. The test tube contains a colourless liquid and tar. The gas collection tube indicates water, colourless liquid, and tar.] The distillate is a mixture of a colourless liquid and tar.

1. (a)The colourless liquid contains ammonia, NH3. Draw a 'dot-and-cross' diagram for ammonia. Show only the outer shell electrons.[2]
2. (b)The tar contains ethanoic acid. When warmed in the presence of sulfuric acid, ethanoic acid reacts with propanol to form an ester. Name and draw the structure of this ester showing all the atoms and all the bonds. name structure[2]
3. (c)The tar also contains a compound with the following composition. | element | percentage by mass | |---|---| | carbon | 76.60 | | hydrogen | 6.38 | | oxygen | 17.02 | Deduce the empirical formula of this compound. empirical formula[2]
4. (d)(i)When coal is burned, an acidic gas is produced which decolourises acidified aqueous potassium manganate(VII). This gas contributes to acid rain. Identify this gas and describe how acid rain is formed.[2]
5. (d)(ii)Give one adverse effect of acid rain on buildings.[1]
6. (d)(iii)Acid rain can have an adverse effect on respiration. Write an equation to represent the process of respiration.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.