The reaction of pure aluminium is only observed if the aluminium oxide layer is removed first. When pure aluminium is added to cold water, bubbles of gas are seen.

1. (a)The reaction of pure aluminium is only observed if the aluminium oxide layer is removed first. When pure aluminium is added to cold water, bubbles of gas are seen.
2. (a)(i)State one property of aluminium oxide that explains why an aluminium object does not react with cold water until the aluminium oxide layer is removed.[1]
3. (a)(ii)Write an equation, with state symbols, for the reaction of aluminium oxide with an excess of NaOH(aq).[2]
4. (a)(iii)Name one other Period 3 element that also produces bubbles of gas when added to cold water.[1]
5. (b)Aluminium nitrate is a white soluble salt. On heating aluminium nitrate, thermal decomposition occurs and a brown gas is seen. State the formula of the salt of another element in Period 3 which also decomposes on heating to produce a brown gas.[1]
6. (c)Aluminium chloride and phosphorus chloride are both white solids.
7. (c)(i)State the maximum oxidation number of aluminium and of phosphorus in these solid chloride salts. maximum oxidation number of aluminium maximum oxidation number of phosphorus[1]
8. (c)(ii)State why the maximum oxidation number of aluminium is different from that of phosphorus.[1]
9. (c)(iii)Write an equation for the reaction of solid phosphorus chloride and excess water.[1]
10. (c)(iv)Name the type of reaction that occurs when aluminium chloride is added to water.[1]
11. (c)(v)Explain why the solution produced after aluminium chloride is added to water has a pH of 1-2.[1]