Find percentage purity－航空百大

標題:

Find percentage purity

發問:

It was found by analysis that an impure sample of ammonium sulphate contained 24.59% by mass of NH4+ ion. Calculate the percentage purity of the sample. (Ans：90.17%)

最佳解答:

It was found by analysis that an impure sample of ammonium sulphate contained 24.59% by mass of NH4+ ion. Calculate the percentage purity of the sample. Assume that the impurity does not contain NH4^+ ion. Molar mass of NH4^+ ion = 14 + 1x4 = 18 g/mol Molar mass of (NH4)2SO4 = 18x2 + 32 + 16x4 = 132 g/mol Mass fraction of NH4^+ ion in (NH4)2SO4 = 18x2/132 = 36/132 Consider 1 g of the sample: Mass of NH4^+ ion in the sample = 1 x 24.59% = 0.2459 g Mass of (NH-4)2SO4 in the sample = 0.2459 ÷ (36/132) = 0.9016 g Percentage purity of the sample = (0.9016/1) x 100% = 90.16%