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InterviewSolution
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An aqueous solution contains `10%` ammonia by mass and has a density of `0.09g cm^(-3)`. Calculate hydroxyl and hydrogen ion concentration in this solution. `(K_(a)for NH_(4)^(+)=5.0xx10^(-10)M)` |
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Answer» Given, `(wt.of NH_(3))/("wt.of solution")=(10)/(100)` `.: 100g "solution contains "10 g NH_(3)` `:. M_(NH_(3))=(10xx1000)//[17xx100//0.99)]=5.82` `(.: V= "Mass"//"Density")` Now `{:( NH_(3)+H_(2)Orarr, NH_(4)OH hArr NH_(4)^(+),+OH^(-)),("Before dissociation",1,0,0),("After dissociation",(1-alpha),alpha,alpha):}` `:. [OH^(-)]=C.alpha=Csqrt((K_(b)//C))=sqrt((K_(b).C))` `[.: C = 5.82 M and K_(b)=K_(w)//K_(a)=10^(-14)//(5xx10^(-10))=2xx10^(-5)]` `:. [OH^(-)]=sqrt([2xx10^(-5)xx5.82])=1.07xx10^(-2)M` `:. [H^(+)]=10^(-14)//1.07xx10^(-2)` `=.09268xx10^(-12)M` `:. pH= -log [H^(+)]= - log 0.9268xx10^(-12)` `=12.0330` |
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