Question

Sodium and Potassium were determinate in a sample of feldspar of 0.5035 g, first metals were isolated in form of combined chlorides. The mixture of NaCl y KCl weighted 0.1208 g. This mixture was dissolved in water and treated with AgNO₃, forming 0.2513 g of AgCl. Calculate the percentages of Na₂O and K₂O in feldspar.

Answer 1

The mixture of NaCl y KCl weighted 0.1208 g

No of mol of AgCl = 0.2513/143.32   = 0.001753 mol

No of mol of Cl = 0.001753 mol

mass of Cl = 0.001753*35.5 = 0.0622 grams

mass of Na,K in the mixture = 0.1208-0.0622 = 0.0586

molar mass ratio of Na,K = 23/39 = 0.56

total mass of Na+k = 0.0586 grams

Na mass in the mixture = 0.0586/1.56 = 0.0376 grams

K mass in the mixture   = 0.0586-0.0376 = 0.021 grams

no of mol of Na = 0.0376/23 = 0.00163 mol

No of mol of K = 0.021/39 = 0.00538 mol

1 mol Na2O = 2 mol Na

1 mol k2o = 2 mol K

mass of Na2O = (0.00163/2)*61.9789 = 0.0505 grams

mass of K2O = (0.00538/2)*94.2 = 0.25 grams

mass of (Na2o+K2O) in mixture = 0.25+0.0505 = 0.3005 grams

percent of (Na2o+K2O) in mixture = 0.3/0.5035*100

   = 59.583%