Question

$1$ L sample of impure water containing sulphide ion is made ammonial and is titrated with $300$ mL of $0.1M$ $AgN{O}_3$ solution. Which of the following statements is/are correct about the above reaction?

• A. The strength of $H_{2}S$ in water is $0.51$ g/L.
• B. The strength of $H_{2}S$ in water is $5.1$ g/L.
• C. The concentration of $H_{2}S$ in water in ppm is $510$.
• D. The concentration of $H_{2}S$ in water in ppm is $51$.

Answer 1

Answer: (A), (C)

The strength of $H_{2}S$ in water is $0.51$ g/L.
The concentration of $H_{2}S$ in water in ppm is $510$.

Milliequivalents of $H_{2}S=$ Milliequivalents of $S^{2-}=$ Milliequivalents of $AgN{O}_3$
$\frac{W}{\frac{34}{2}}\times 1000$ $=300\times 0.1$ ($n$-factor$=1$) $=30$
$\therefore W_{H_{2}S}=\frac{30\times 17}{1000}=0.51$ g/L
ppm of $H_{2}S=\frac{0.51\times {10}^6}{{10}^3}=510$

Hence, options A and C are correct.