Question

Sodium fusion extract of an organic compound (Y) with CHCl\(_3\) and chlorine water gives violet colour to the CHCl\(_3\) layer. \(0.15\,\text{g}\) of (Y) gave \(0.12\,\text{g}\) of the silver halide precipitate in Carius method. Percentage of halogen in the compound (Y) is _________ (Nearest integer). 
Given: 
\[ \text{C} = 12,\quad \text{H} = 1,\quad \text{Cl} = 35.5,\quad \text{Br} = 80,\quad \text{I} = 127 \]

Hint:

In Lassaigne’s test, bromine gives a brownish-violet colour in the CHCl\(_3\) layer with chlorine water, while iodine gives a deep violet colour.

Answer 1

Correct Answer: 34

The problem involves determining the percentage of halogen in a compound (Y) using the Carius method. Let's break down the solution methodically:

Step 1: Determine the Type of Halogen
The sodium fusion extract gives a violet color with CHCl\(_3\) and chlorine water, indicative of iodine. Hence, we are dealing with iodine in the compound.

Step 2: Use the Carius Method to Determine Halogen Content
In the Carius method, the organic compound is subjected to oxidation, and the released halogen forms a silver halide precipitate with silver nitrate.

Given:
\(0.15\:\text{g}\) of compound (Y) yields \(0.12\:\text{g}\) of silver iodide (AgI).

The molar mass of AgI = Ag + I = 107.9 + 127 = 234.9 g/mol.

Step 3: Calculate the Moles of AgI Formed
Moles of AgI = \(\dfrac{\text{mass of AgI}}{\text{molar mass of AgI}} = \dfrac{0.12}{234.9} \approx 0.000511\:\text{mol}\).

Step 4: Calculate the Mass of Iodine in the AgI
Mass of iodine in AgI = Moles of AgI \(\times\) molar mass of I = \(0.000511 \times 127 \approx 0.0649\:\text{g}\).

Step 5: Calculate the Percentage of Iodine in Compound (Y)
Percentage of iodine = \(\left(\dfrac{\text{mass of iodine in AgI}}{\text{mass of compound (Y)}}\right) \times 100 = \left(\dfrac{0.0649}{0.15}\right) \times 100 \approx 43.27\%\).

Upon rounding, the nearest integer is 43.

Validation: The calculated percentage falls outside the specified range (34,34), possibly due to provided specifications or an error in measured data.

Conclusion: The percentage of iodine in compound (Y) is calculated to be 43 (as a nearest integer), but this does not fit the specified expected range. This indicates a need for reevaluation with given constraints or intended data correction.