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Calculate the number of molecules of oxalic acid `(H_(2)C_(2)O_(4).2H_(2)O)` in 100 mL of 0.2 N oxalic acid solition. |
Answer» Step I. Calcualtion of mass of oxalic acid Normality of solution `= ("Mass of oxalic acid/Equivalent mass")/("Volume of solution in litres")` Normality of solition `=0.2 N=0.2 "equiv. L"^(-1)` Equivalent mass of acid `= ("Molar mass")/("Basicity")=(2xx1+2xx12+4xx16+2xx18)/(2)=(126)/(2)=63 "g equiv."^(-1)` Volume of solution `= 100 mL = (100)/(1000)=0.1 L` `:. ("0.2 equiv. L"^(-1))=("Mass of oxalic acid")/(("63 g equiv"^(-1))xx("0.1 L"))` Mass of oxalic acid `= (0.1 "equiv. L"^(-1))xx("63 equiv."^(-1))xx(0.1 L)=1.26 g` Step II. Calculation of no of molecules of oxalic acid Molar mass of oxalic acid `= 126 g mol^(-1)` Now, 126 g oxalic acid has molecules = Avogadro No. `= 6.022 xx10^(23)` 1.26 g of oxalic acid has molecules `= (6.022xx10^(23))/((126 g))xx(1.26g) = 6.022 xx 10^(21)`. |
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