Ammonium hydrogenosulfide (s) dissociates itself according to:
$NH_4HS(s)$ $NH_3(g)+H_2S(g)$,
with $K=1.81\cdot10^{-4} $ $M^2$ at $25^oC$
This substance is introduced in an empty container.
- Calculate the molarities of the two gases at equilibrium!
- Calculate the total pressure at equilibrium!
$ K$ $=$ $[NH_3]\cdot [H_2S]$
When one mole of $NH_4HS$ has dissociated itself, 1 mole of ammonia and 1 mole of hydrogen sulfide have been formed, so, at equilibrium:
$[NH_3]$ $=$ $[H_2S]$ $=$ $x$
$K$ $=$ $x^2$
$x$ $=$ $[NH_3]$ $=$ $[H_2S]$ $=$ $\sqrt{K}$ $=$ $\sqrt{1,81\cdot10^{-4}}$ $=$ $0.0135$ M
$p_{NH_3}$ $=$ $p_{H_2S}$ $=$ $x\cdot RT$ $=$ $0.0135\cdot 0.082\cdot 298.15$ $=$ $0.330 \;atm$
$P$ $=$ $p_{NH_3}$ $=$ $p_{H_2S}$ $=$ $0.330$ $+$ $0.330$ $=$ $0.660 \; atm$
$NH_3(g)+H_2S(g)$,
with $K=1.81\cdot10^{-4} $ $M^2$ at $25^oC$
This substance is introduced in an empty container.
- Calculate the molarities of the two gases at equilibrium!
- Calculate the total pressure at equilibrium!