Question

In Sulphur estimation, 0.7 g of an organic compound gives 1 g of BaSO₄ by Carius method. What is the % of ‘S’ in the compound?

• A. 19.61
• B. 23.85
• C. 27.93
• D. 14.57

Hint:

When calculating the percentage of sulfur in a compound using the Carius method, always account for the molar masses of BaSO₄ and sulfur in the compound.

Answer 1

The Correct Option is A

To find the percentage of Sulphur \((\text{S})\) in the given organic compound using the Carius method, follow these steps:

Understand the chemical reaction and its outcome: In the Carius method, the organic compound containing Sulphur is oxidized to form Barium Sulfate \((\text{BaSO}_4)\). The mass of \(\text{BaSO}_4\) obtained is given as \(1\ \text{g}\).

Calculate the moles of \(\text{BaSO}_4\):

The molar mass of \(\text{BaSO}_4\) is approximately \(233\ \text{g/mol}\).

So, the moles of \(\text{BaSO}_4\) = \(\frac{1\ \text{g}}{233\ \text{g/mol}} = 0.00429\ \text{mol}\).

Relate moles of \(\text{S}\) to moles of \(\text{BaSO}_4\) : Each mole of \(\text{BaSO}_4\) contains one mole of Sulphur (S).

Hence, moles of \(\text{S} = 0.00429\ \text{mol}\).

Calculate the mass of Sulphur: The atomic mass of Sulphur \((\text{S})\) is approximately \(32\ \text{g/mol}\).

So, the mass of \(\text{S} = 0.00429\ \text{mol} \times 32\ \text{g/mol} = 0.13728\ \text{g}\).

Determine the percentage of Sulphur in the organic compound:

The original mass of the organic compound is \(0.7\ \text{g}\).

Therefore, the percentage of \(\text{S}\) in the compound is given by:

\(\frac{0.13728\ \text{g}}{0.7\ \text{g}} \times 100 = 19.61\%\\).

Thus, the percentage of Sulphur in the compound is 19.61%.