Chemistry - Chemical Equilibrium Question with Solution | TestHub

\begin{gathered}{}\text{The}\text{ }\text{equilibrium}\text{ }\text{water}\text{ }\text{pressure}\text{ }\text{for}\text{ }\text{the}\text{ }\text{dodecahydrate/heptahydrate}\text{ }\text{pair}\text{ }\text{is}\text{ }\\{}\text{(2.43}\times\text{10}^{\text{-13}}\text{)}^{\text{1/5}}\text{=0.003}\text{ }\text{atm.}\text{ }\text{When}\text{ }\text{the}\text{ }\text{surrounding}\text{ }\text{water}\text{ }\text{pressure}\text{ }\text{exceeds}\text{ }\text{0.003}\text{ }\\{}\text{atm,}\text{ }\text{the}\text{ }\text{reverse}\text{ }\text{reaction}\text{ }\text{is}\text{ }\text{favoured.}\\{}\text{The}\text{ }\text{heptahydrate}\text{ }\text{then}\text{ }\text{absorbs}\text{ }\text{water}\text{ }\text{to}\text{ }\text{form}\text{ }\text{the}\text{ }\text{dodecahydrate.}\\{}\text{The}\text{ }\text{limiting}\text{ }\text{relative}\text{ }\text{humidity}\text{ }\text{is}\text{ }\text{100(0.003/0.04)=7.5%.}\\{}\text{This}\text{ }\text{is}\text{ }\text{option}\text{ }\text{(c).}\end{gathered}