In the analysis of 0.500 g sample of feldspar, a mixture of chlorides of sodium and potassium is obtained which weighs 0.1180g. Subsequent treatment of mixed chlorides, with silver nitrate gives 0.2451 g of silver chloride. What is the percentage of sodium oxide and potassium oxide in feldspar.
Answers
Weight of feldspar=0.5 gm
Weight of AgCl= 0.2451 gm
Total weight NaCl+KCl = 0.1180 gm
First the mass of AgCl will be solved obtained from NaCl and KCl
2NaCl=Na 2 O and 2KCl=K2O
Let the amount of Nacl be x gm
And the amount of KCl is (0.1180 - x) gm
NaCl + AgNo3 ---> AgCl + NaNO3
58.5 gm NaCl gives = 143.5 gm AgCl
X gm = 143.5/58.5 into x
Similarly for KCl
KCl + AgNO3 ---> AgCl + KNO3
74.5 gm KCl gives = 143.5gm AgCl
(0.1180 - x) gm = 143.5/74.5 x (0.118 - x )
Total weight AgCl (given in the ques) = 0.2451 gm
==>(143.5/58.5) into x + (143.5/74.5) x (0.118 - x)) = 0.2451
When we solve this we get x= 0.0338 gm
Amount of KCl = (0.118-0.0338) = 0.0842gm
2 NaCl = Na2O
2x58.5 = 62
117gm=62gm
====> 0.0338 = 62/117 x 0.0338
= 0.0179 gm Na2O
%Na2O in 0.5 gm feldspar = 0.0179/0.5 x 100 = 3.58%
Similarly for 2KCl = K2O
2x74.5 = 94
149 gm = 94 gm
149 gm KCl = 94 gm K2O
So ===> 0.0842 = 94/149 x 0.0842 = 0.0531 gm K2O
% K2O in 0.5gm feldspar = 0.0531/0.5 x 100 = 10.62 % K2O
Na2O= 3.58 %
K2O = 10.62%