Equilibrium Question 770
Question: If $ CuSO_4.5H_2O(s)\rightarrow $
$ CuSO_4.3H_2O( s )+2H_2O( g ) $
$ K_{p}=1.086\times {10^{-4}}atm^{2} $ at $ 25{}^\circ C $ . The efflorescent nature of $ CuSO_4.5H_2O $ can be noticed when the vapour pressure of $ H_2O $ in atmosphere is
Options:
A) >9.72mm
B) <7.92mm
C) >7.92mm
D) < 11.92mm
Show Answer
Answer:
Correct Answer: B
Solution:
The efflorescent salts loss water to atmosphere $ K_{p}=p _{H_2O}^{2}=1.086\times {10^{-4}}; $
$ {p_{H_2O}}=1.042\times {10^{-2}}atm=7.92mm $ If $ H_2O $ pressure at $ 25{}^\circ C $ is less than 7.92 mm. The reaction $ CuSO_4.5H_2O( s )\xrightarrow{{}}CuSO_4.3H_2O( s )+H_2O( g ) $ will not proceed in RHS.
