Question

An equimolar mixture of NaCl and KCl weigh 266 mg. Find mass of AgCl produced on addin
AgNO, to above mixture.
(1) 143.5 mg
(2) 574 mg
(3) 287 mg (4) None of these
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Answer 1

Answer:

The correct option is 2.

Explanation:

xKCl + yNaCl + (x+y)AgNO3 = xKNO3 + yNaNO3 + (x+y)AgCl

Let x moles of KCl and y moles of NaCl present in the mixture

The moles of AgCl formed = x+y = 2/143.5 moles

Therefore

x + y = 2/143.5 --------------(1)

Given that, 74.5x +58.5y = 1 -----------(2)

solving the two equations for x,y

multiply first equation by 74.5

74.5x + 74.5y = 2 x 74.5/143.5 = 149/143.5 = 1.038

74.5x + 58.5y = 1

(74.5-58.5)y = 1.038 -1

y = 0.038/16 = 0.00237 moles

mass of NaCl = 0.0237 x 58.5 = 0.139 g = 14%

mass of KCl = 1 - 0.139 = 0.861 g = 86%

The composition of original mixture is 14 % NaCl and 86% KCl.

So the correct option is B.