Question

from your work on the previous screen, you saw that single - replacement reactions follow the general pattern:

$a + bc \to ac + b$

based on this, which of the reactions below are single - replacement reactions?

$\square 2al(s)+fe_{2}o_{3}(s)\to al_{2}o_{3}(s)+2fe(l)$

$\square 2al(s)+3cuo(s)\to 3cu(s)+al_{2}o_{3}(s)$

$\square zns(s)+2hcl(aq)\to zncl_{2}(aq)+h_{2}s(g)$

$\square caco_{3}(s)+2hcl(aq)\to cacl_{2}(aq)+h_{2}co_{3}(aq)$

Explanation:

• For the reaction \(2Al(s)+Fe_{2}O_{3}(s)\to Al_{2}O_{3}(s)+2Fe(l)\):
• Here, \(Al\) (A) replaces \(Fe\) (B) in \(Fe_{2}O_{3}\) (\(BC\)). The general form \(A + BC\to AC + B\) is followed (\(Al\) is \(A\), \(Fe_{2}O_{3}\) is \(BC\), \(Al_{2}O_{3}\) is \(AC\), \(Fe\) is \(B\)).
• For the reaction \(2Al(s)+3CuO(s)\to 3Cu(s)+Al_{2}O_{3}(s)\):
• \(Al\) (A) replaces \(Cu\) (B) in \(CuO\) (\(BC\)). It follows the \(A + BC\to AC + B\) pattern (\(Al\) is \(A\), \(CuO\) is \(BC\), \(Al_{2}O_{3}\) is \(AC\), \(Cu\) is \(B\)).
• For the reaction \(ZnS(s)+2HCl(aq)\to ZnCl_{2}(aq)+H_{2}S(g)\):
• This is a double - replacement reaction (the general form \(AB+CD\to AD + CB\), where \(ZnS\) is \(AB\), \(HCl\) is \(CD\), \(ZnCl_{2}\) is \(AD\), \(H_{2}S\) is \(CB\)) and not a single - replacement reaction.
• For the reaction \(CaCO_{3}(s)+2HCl(aq)\to CaCl_{2}(aq)+H_{2}CO_{3}(aq)\):
• This is also a double - replacement reaction (the general form \(AB + CD\to AD+CB\), where \(CaCO_{3}\) is \(AB\), \(HCl\) is \(CD\), \(CaCl_{2}\) is \(AD\), \(H_{2}CO_{3}\) is \(CB\)) and not a single - replacement reaction.

Answer:

• \(2Al(s)+Fe_{2}O_{3}(s)\to Al_{2}O_{3}(s)+2Fe(l)\)
• \(2Al(s)+3CuO(s)\to 3Cu(s)+Al_{2}O_{3}(s)\)