Question

In the system, LaCl3(s) + H2O(g) + heat LaClO(s) + 2HCl(g), equilibrium is established. More water vapour is added to restablish the equlibrium. The pressure of water vapour is doubled. The factor by which pressure of HCl is changed is:

• A. 2
• B. $\sqrt { 2 }$
• C. $\sqrt { 3 }$
• D. $\sqrt { 5 }$

Answer 1

Answer: (B)

$\sqrt { 2 }$

Answer 2

LaCl3(s) + H2O(g) + heat $\longrightarrow$ LaClO(s) + 2HCl(g)

$\mathrm { K } _ { \mathrm { p } } = \frac { \mathrm { p } _ { \mathrm { HCl } } ^ { 2 } } { \mathrm { p } _ { \mathrm { H } _ { 2 } \mathrm { O } } } = \frac { \mathrm { p } _ { \mathrm { HCl } } ^ { 2 } } { 2 \mathrm { p } _ { \mathrm { H } _ { 2 } \mathrm { O } } } \quad \mathrm { p } _ { \mathrm { HCl } } = \sqrt { 2 } \mathrm { P } _ { \mathrm { HCl } }$