Question

8 Would your exper ould your experimental percent sulfate be high or low if your alum sample had a soluble non-sultate writy, for example, water to prove your answer, do the following calculation. Assume that included in the weight of a sample of alum are 0.10 g of water. The total weight of sample is 1.20 g. Calculate the percent sulfate in the sample.

Answer 1

Example A soluble non sulfate impurity decreases the Sulfat percent in sample because percent of pure alum decreases. Alum - kusou Al(SO4)3.24 H₂O K, = 39X2 = 78 AL2 = 27 x 2 =54 (SO4)3+1 = 96x4 = 384 24 H2O = 18 x 24 = 432 molar mass of Alum= 948 g/mol " " Sulphate = 38491 med percent of sulphate in Alum = 384 g/mol (massol so) loo 948g 1 mol(mass of Alom) = 40.5 4. Sulphate in Alum % of Alum in impure sample = 10o-impasity. 1. impurity of water = mass of water xlo Total mass lo Xloo 120 = 0.3 Alum in sample = 91.7% 948g Alum contain a 304 g scelphate . 9079 " - 384917 = 37.14 948 Thi$ 37.14 g sulphate it from loog impark sample. so percent of sculphate in impure sample=37.14% sulphat in pure sample = 40.51.. So, impurity decreased sulphate persent in Al4m.