Question

The hydrogen ion concentration of a `10^(-8) M HCl` aqueous soultion at `298 K(K_(w)=10^(-14))` is
A. `9.525xx10^(-8) M`
B. `1.0xx10^(-8) M`
C. `1.0xx10^(-6) M`
D. `1.0525xx10^(-7) M`

Answer 1

Correct Answer - D
`HClrarrunderset(10^(-8) M)(H^(+))+Cl^(-)`
`H_(2)OhArrunderset(10^(-8)+a)(H^(+))+underset(a)(OH^(-))`
`K_(w)=[H^(+)][OH^(-)]`
`:. K_(w)=(10^(-8)+a)xxa`
or `10^(-14)=10^(-8)a+a^(2)`
or `a=0.95xx10^(-7)`
`:. [H^(+)]=10^(-8)+0.95xx10^(-7)`
`=1.05xx10^(-7)`