InterviewSolution
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InterviewSolution
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Equal volumes of the following `Ca^(2+)` and `F^(-)` solutions are mixed. In which of the solutions will precipitations occur ? `[K_(sp)` of `CaF_(2)=1.7 xx 10^(-10)]` 1. `10^(-2) M Ca^(2+)+10^(-5)MF^(-)` 2. `10^(-3) M Ca^(2)+10^(-3)MF^(-)` 3. `10^(-4) MCa^(2)+10^(-2)MF^(-)` 4. `10^(-2) MCa^(2)+10^(-3)MF^(-)` Select the correct answer using the codes given belowA. In 4 onlyB. In 1 and 2C. In 3 and 4D. In 2,3 and 4 |
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Answer» Correct Answer - C In case I `[Ca^(2+)]` in reaction mixture `=0.5 xx 10^(-2)M` `[F^(-)]` in reaction mixture `=0.5 xx 10^(-5)M` `:. ` Ionic product `=[Ca^(2+)][F^(-)]^(2)=(0.5 xx 10^(-2))xx (0.5 xx10^(-5))^(2)` `=125 xx 10^(-15)=1.25 xx 10^(-13)xx1.7 xx 10^(-10)` `:. `No. ppt is formed in this case In case 2 `[Ca^(2+)]` in reaction mixture `=0.5 xx 10^(-3)M` `[F^(-)]` in reaction mixture `=0.5 xx 10^(-3)M` `:. `Ionic product `=(0.5 xx 10^(-3))(0.5 xx 10^(-3))^(2)` `=125 xx 10^(-12)=1.25 xx 10^(-10)lt 1.7 xx 10^(-10)` No. ppt. is formed in this case In case 3 `[Ca^(2+)]` in reaction mixture `=0.5 xx 10^(-4)M` `[F^(-)]` in reaction mixture `=0.5 xx 10^(-2)M` `:. ` Ionic product `=[Ca^(2+)]xx[F^(-)]^(2)` `=[0.5 xx 10^(-4)] xx [0.5 xx 10^(-2)]^(2)` `=125 xx 10^(-11)` `=1.25 xx 10^(-9) gt 1.7 xx 10^(-10)` Thus a ppt. of `CaF_(2)` will be formed In case 4 `[Ca^(2+)]` in reaction mixture `=0.5 xx 10^(-2)M` `[F^(-)]` in reaction mixture `=0.5 xx 10^(-3)M` Ionic product `[Ca^(2+)][F^(-)]^(2)` `=[0.5 xx 10^(-2)][0.5 xx 10^(-3)]^(2)=125 xx 10^(-11)` `=1.25 xx 10^(-9) gt 1.7 xx 10^(-10)` Thus a ppt of `CaF_(2)` will be formed. |
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