Chemical and Ionic Equilibrium 1 Question 24

25. An example of a reversible reaction is

$(1985,1 \mathrm{M})$

(a) $\mathrm{Pb}\left(\mathrm{NO}{3}\right){2}(a q)+2 \mathrm{NaI}(a q)=\mathrm{PbI}{2}(s)+2 \mathrm{NaNO}{3}(a q)$

(b) $\mathrm{AgNO}{3}(a q)+\mathrm{HCl}(a q)=\mathrm{AgCl}(s)+\mathrm{HNO}{3}(a q)$

(c) $2 \mathrm{Na}(s)+2 \mathrm{H}{2} \mathrm{O}(l)=2 \mathrm{NaOH}(a q)+\mathrm{H}{2}(g)$

(d) $\mathrm{KNO}{3}(a q)+\mathrm{NaCl}(a q)=\mathrm{KCl}(a q)+\mathrm{NaNO}{3}(a q)$

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Solution:

  1. In reactions (a), (b) and (c), atleast one of the product is either insoluble precipitate or a gas that drive the reaction continuously to right and do not allow equilibrium to be established. Following is the reversible reaction.

$$ \mathrm{KNO}{3}(a q)+\mathrm{NaCl}(a q) \rightleftharpoons \mathrm{KCl}(a q)+\mathrm{NaNO}{3}(a q) $$