Gọi `a` là `V_X`
`∑[OH^-]=0,2+2.0,1=0,4(M)`
`=>n_{OH^-}=0,4V(mol)`
`∑[H^+]=2.0,25+0,75=1,25(M)`
`=>n_{H^+}=1,25.0,04=0,05(mol)`
`OH^{-} +H^+ ->H_2O`
`n_{OH^-}=n_{H^+}`
`=>0,4V=0,05`
`=>V=0,125(l)`
`\text{___________________________________}`
Đáp án:
`V=0,125(l)=125(ml)`