Question

can you identify the double displacement reactions from the following list?
(i) ( mathrm{pb}+mathrm{cucl}_{2}
ightarrow mathrm{pbcl}_{2}+mathrm{cu} )
(ii) ( mathrm{na}_{2} mathrm{so}_{4}+mathrm{bacl}_{2}
ightarrow mathrm{baso}_{4}+2 mathrm{nacl} )
(iii) ( mathrm{c}+mathrm{o}_{2}
ightarrow mathrm{co}_{2} )
(iv) ( mathrm{ch}_{4}+2 mathrm{o}_{2}
ightarrow mathrm{co}_{2}+2 mathrm{h}_{2} mathrm{o} )
( a ) (i) and (iv)
( b ) (ii) only
( c ) (i) and (iii)
( d ) (iii) and (iv)

Explanation:

Step1: Recall the definition of double displacement reaction

A double displacement reaction is a reaction where the positive and negative ions of two ionic compounds exchange places.

Step2: Analyze reaction (i)

In \(Pb + CuCl_2
ightarrow PbCl_2+Cu\), it is a single displacement reaction (a more reactive metal \(Pb\) displaces \(Cu\) from \(CuCl_2\)).

Step3: Analyze reaction (ii)

In \(Na_2SO_4 + BaCl_2
ightarrow BaSO_4+2NaCl\), \(Na^{+}\) from \(Na_2SO_4\) and \(Ba^{2 +}\) from \(BaCl_2\) exchange their negative counterparts (\(SO_4^{2-}\) and \(Cl^{-}\)). This is a double - displacement reaction.

Step4: Analyze reaction (iii)

In \(C + O_2
ightarrow CO_2\), it is a combination reaction (two substances \(C\) and \(O_2\) combine to form \(CO_2\)).

Step5: Analyze reaction (iv)

In \(CH_4+2O_2
ightarrow CO_2 + 2H_2O\), it is a combustion reaction.

Answer:

B. (ii) only