单选题(共9题,100.0分)-|||-8.(10.0分)-|||-已知 _(a)^theta (HAc)=1.75times (10)^5 , 0.10molcdot (L)^-1HAc 和15mL-|||-.20molcdot (L)^-1NaOH 溶液混合。试计算混合后溶液的:-|||-A . =2.88-|||-B =8.79-|||-C =2.88-|||-__-|||-D =8.79

过程:A 混合后溶液为等浓度的HAC和NaAC溶液,混合后溶液的酸度主要由HAC电离决定,${K}_{a}^{\theta }=\dfrac{c(H{}^{+})\cdot c(A{c}^{-})}{c(HAC)}$ , $c(H{}^{+})=c(A{c}^{-})$ , $c(HAC)=0.10\times 30\div (30+15)=0.15mol\cdot {L}^{-1}$ , $c(H{}^{+})={K}_{a}^{\theta }\div c(A{c}^{-})=1.75\times {10}^{-5}\div 0.15=1.17\times {10}^{-5}$ , $PH=-lgc(H{}^{+})=-lg1.17\times {10}^{-5}=4.88$
A