Equal volumes of three acid solutions of pH 3, 4 and 5 are mixed in a vessel. What will be the `H^(+)` ion concentration in the mixture ?

Options

A. `1.11xx10^(-4)M`
B. `3.7xx10^(-4)M`
C. `3.7xx10^(-3)M`
D. `1.11xx10^(-3)M`

Answer

B

Explanation

`[H_(3)O]^(+)` for a solution having pH=3 is given by
`[H_(3)O]^(+)=1xx10^(-3)` moles/litre
`[therefore [H_(3)O]=10^(-pH)`]
Similarly for solution having pH=4,
`[H_(3)O]^(+)=1xx10^(-4)` moles/litre and for pH=5
`[H_(3)O^(+)]=1xx10^(-5)` moles/litre
Let the volume of each solution in mixture be 1L, then total volume of mixture solution L=(1+1+1)L=3L Total `[H_(3)O]^(+)` ion present in mixture solution `=(10^(-3)+10^(-4)+10^(-5)` moles
Then `[H_(3)O]^(+)` ion concentration of mixture solution
`=(10^(-3)+10^(-4)+10^(-5))/(3)M=(0.00111)/(3)M`
`=0.00037 M=3.7xx10^(-4)M`