SATHEE: Some Basic Concepts of Chemistry

Some Basic Concepts of Chemistry - Result Question 59

####58. In the analysis of $0.5 g$ sample of feldspar, a mixture of chlorides of sodium and potassium is obtained, which weighs $0.1180 g$ . Subsequent treatment of the mixed chlorides with silver nitrate gives $0.2451 g$ of silver chloride. What is the percentage of sodium oxide and potassium oxide in the sample?

$(1979, 5 M)$

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Solution:

Oxides of sodium and potassium are converted into chlorides according to following reactions :

$\begin{aligned} N a_{2} O + 2 H C l & ⟶ 2 N a C l + H_{2} O K_{2} O + 2 H C l & ⟶ 2 K C l + H_{2} O \end{aligned}$

Finally all the chlorides of $N a C l$ and $K C l$ are converted into $A g C l$ , hence

$moles of (N a C l + K C l) = moles of A g C l$

(one mole of either $N a C l$ or $K C l$ gives one mole of $A g C l$ )

Now, let the chloride mixture contain $x g N a C l$ .

$\Rightarrow \frac{x}{58.5} + \frac{0.118 - x}{74.5} = \frac{0.2451}{143.5}$

Solving for $x$ gives $x = 0.0338 g$ (mass of $N a C l$ )

$\Rightarrow$ Mass of $K C l = 0.118 - 0.0338$

$= 0.0842 g$

Also, moles of $N a_{2} O = \frac{1}{2} \times$ moles of $N a C l$

$\Rightarrow$ Mass of $N a_{2} O = \frac{1}{2} \times \frac{0.0338}{58.5} \times 62 = 0.0179 g$

Similarly, mass of $K_{2} O = \frac{1}{2} \times \frac{0.0842}{74.5} \times 94 = 0.053 g$

$\Rightarrow$ Mass of $N a_{2} O = \frac{0.0179}{0.5} \times 100 = 3.58$

Mass of $K_{2} O = \frac{0.053}{0.5} \times 100 = 10.6$

Some Basic Concepts of Chemistry - Result Question 59

Solution:

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Some Basic Concepts of Chemistry - Result Question 59

Solution:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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