Solid NH4HS and solid NH4Cl are both present in an evacuated vessel at fixed temperature, so that NH4HS(s) NH3(g) + H2S(g) (K_p1 = 0.12 atm^2) and NH4Cl(s) NH3(g) + HCl(g) (K_p2 = 0.30 atm^2) are simultaneously at equilibrium. Which statements are correct?

The total pressure is about 1.30 atm

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ce110

Solid $NH X_{4} HS$ and solid $NH X_{4} Cl$ are both present in an evacuated vessel at fixed temperature, so that $NH X_{4} HS (s) NH X_{3} (g) + H X_{2} S (g)$ ( $K_{p 1} = 0.12 at m^{2}$ ) and $NH X_{4} Cl (s) NH X_{3} (g) + HCl (g)$ ( $K_{p 2} = 0.30 at m^{2}$ ) are simultaneously at equilibrium. Which statements are correct?

NH X_{3}

is shared, so

p_{NH X_{3}} = p_{H X_{2} S} + p_{HCl}

. With

p_{H X_{2} S} = 0.12/ p_{NH X_{3}}

and

p_{HCl} = 0.30/ p_{NH X_{3}}

we get

p_{NH X_{3}}^{2} = 0.42

, so

p_{NH X_{3}} = 0.648

atm,

p_{H X_{2} S} = 0.185

atm and

p_{HCl} = 0.463

atm. Total

= 2 p_{NH X_{3}} = 1.30

atm. Statements 1 and 3 are correct; statement 2 uses the

H X_{2} S

value, and statement 4 ignores the second equilibrium.