For the equilibrium system `2HX (g) hArr H _(2) (g) +X _(2) (g)` the equilibrium constant is `1.0 xx10^(-5).` What is the concentration of HX if the equilibrium concentration of `H_(2) and X_(2)` are `1.2 xx10^(-3) M, and 1.2 x10^(-4) M `respectively?

Options

A. `12 xx 10^(-4)M`
B. `12 xx 10^(-3)M`
C. `12 xx 10^(-2)M`
D. `12 xx 10^(-1)M`

Answer

C

Explanation

`{:(,2HX(g),hArr,H_(2)(g),+,X_(2)(g)),("At equilibrium",,,1.2 xx 10^(-3)M,,1.2 xx 10^(-4)M):}`
`K = ([H_(2)][X_(2)])/([HX]^(2)), 10^(-5) = (1.2 xx 10^(-3) xx 1.2 xx 10^(-4))/([HX]^(2)) rArr [HX] = sqrt((1.2 xx 1.2 xx 10^(-7))/(10^(-5))) = 1.2 xx 10^(-1) = 12 xx 10^(-2)M`