What is the `[OH^(-)]` in the final solution prepared by mixing `20.0 mL` of `0.050 M` `HCl` with `30.0 mL` of `0.10 M` `Ba(OH)_(2)`?

Options

A. `0.10 M`
B. `0.40 M`
C. `0.0050 M`
D. `0.12 M`

Answer

A

Explanation

Number of milliequivalents of HCl
`=20xx0.0.050xx1=1`
Number of milliequivalents of `Ba(OH)_(2)`
`=2xx30xx0.10=6`
`[OH^(-)]` of final solution
Milliequivalents of `Ba(OH)_(2)`
`=("- milliequivalents of HCl")/("Total volume")=(6-1)/(50)`
`= 0.1 M`