(a)(i) Arrange the following elements in the order of increasing reactivity. Iron, Lead, Magnessium, Aluminium. (ii) Which of the following elements in (a)(...
Question 1 Report
(a)(i) Arrange the following elements in the order of increasing reactivity. Iron, Lead, Magnessium, Aluminium.
(ii) Which of the following elements in (a)(i) above reacts with sodium hydroxide to give hydrogen?
(b) What property of tetraoxosulphate (VI) acid does each of the following reactions illustrate?
(I) S + 2H\(_2\)SO\(_4\) ---> 3SO\(_4\) + 2H\(_2\)O
(ii) MgO + H\(_2\)SO\(_4\) ---> MgSO\(_4\) + H\(_2\)O
(iii) C\(_{12}\)H\(_{22}\)C\(_{11}\) + H\(_2\)SO\(_4\) ---> 12C + H\(_2\)SO\(_4\) + 11H\(_2\)O
Answer Details
(a)(i) Arranged in order of increasing reactivity (least reactive first):
\[Lead < Iron < Aluminium < Magnesium\]
i.e. Lead, Iron, Aluminium, Magnesium (magnesium is the most reactive of the four).
(ii) The element that reacts with sodium hydroxide to give hydrogen is aluminium (it is amphoteric and reacts with alkalis to liberate hydrogen).
(b) Property of tetraoxosulphate(VI) acid illustrated by each reaction:
- (i) \(S + 2H_2SO_4 \rightarrow 3SO_2 + 2H_2O\): hot concentrated \(H_2SO_4\) is acting as an oxidizing agent (it oxidizes sulphur, and is itself reduced to \(SO_2\)). This shows its oxidizing property.
- (ii) \(MgO + H_2SO_4 \rightarrow MgSO_4 + H_2O\): the acid reacts with a base to give salt and water only. This shows its acidic property (neutralization).
- (iii) \(C_{12}H_{22}O_{11} + H_2SO_4 \rightarrow 12C + H_2SO_4 + 11H_2O\): the acid removes the elements of water from sugar, leaving carbon. This shows its dehydrating property.
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