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What is the pH of `10^(-3)` M ammonia cyanide solution, if `K_(HCN)=7.2 xx 10^(-11)` and `K_(NH_(3))=1.8 xx 10^(-5)mol L^(-1)` ?A. 14B. 9.7C. `12.0`D. `7.5` |
Answer» Correct Answer - B `[H^(+)]` for the salt of weak acid and weak base is given by the expression `[H^(+)]=sqrt((K_(w)xx K_(a))/(K_(b)))` `=sqrt((10^(-14)xx7.2 xx 10^(-11))/(1. 8 xx 10^(-5)))=2 xx 10^(-10)` `pH =-log 2 xx 10^(-10)=10-log2` `=10-0.3010=9.699` |
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