Question

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume ?
(a) $PCl_{5}(g)\rightleftharpoons PCl_{3}(g)+Cl_{2}(g)$
(b) $CaO(s)+CO_{2}(g)\rightleftharpoons CaCO_{3}(s)$

Answer 1

Le Chatelier's principle:

“When an reaction in equilibrium state is subjected to change in either “concentration” or “temperature” or “external pressure”, the equilibrium will shift in forward or reverse direction in which the changes are nullified”.

According Le Chatelier's principle equilibrium shifts to the high pressure side.

$(i)\quad P{ Cl }_{ 5 }\quad (g)\quad \rightleftharpoons \quad P{ Cl }_{ 3 }\quad (g)\quad +\quad { Cl }_{ 2 }(g); Increases$

$(ii)\quad CaO(s)\quad +\quad C{ O }_{ 2 }(g)\quad \rightleftharpoons \quad CaC{ O }_{ 3 }(s); Decreases$

$(iii)\quad 3Fe(s)\quad +\quad 4{ H }_{ 2 }O(g)\quad \rightleftharpoons \quad { Fe }_{ 3 }{ O }_{ 4 }(s)\quad +\quad 4{ H }_{ 2 }(g); Remains\quad the\quad same$