Question

1 gm of organic compound gave 1.32g $\text{CO}_2$, 0.53g of same compound gave 0.75g AgBr. If molecular formula of compound is $\text{C}_x\text{H}_y\text{Br}_z$ then calculate percentage of hydrogen in the given compound.

• A. 2%
• B. 3%
• C. 5%
• D. 4%

Hint:

Always check the sample mass used for each specific estimation analysis. It differs here (1g for C, 0.53g for Br).

Answer 1

The Correct Option is D

To find the percentage of hydrogen in the given compound, we can follow these steps:

1. Calculate the moles of carbon in the compound:
   • We know that 1 mole of CO₂ contains 1 mole of carbon and has a mass of 44 g.
   • The given mass of CO₂ is 1.32 g.
   • Convert this to moles: \(\text{Moles of CO}_2 = \frac{1.32}{44}\) \(\approx 0.03\) moles.
   • Since each mole of CO₂ corresponds to 1 mole of C, the moles of C are also 0.03.
   • The mass of carbon can be calculated as: \(\text{Mass of C} = 0.03 \times 12 = 0.36\) g.
2. Calculate the moles of bromine:
   • 1 mole of AgBr has a mass of (108 + 80) = 188 g.
   • The mass of AgBr provided is 0.75 g.
   • Convert this to moles: \(\text{Moles of AgBr} = \frac{0.75}{188}\) \(\approx 0.004\) moles.
   • Each mole of AgBr contains 1 mole of Br, so the moles of Br are 0.004.
   • Calculate the mass of Br: \(\text{Mass of Br} = 0.004 \times 80 = 0.32\) g.
3. Calculate the mass of hydrogen in the compound:
   • The total mass of the organic compound is 1 g.
   • The mass of hydrogen is given by: \(\text{Mass of H} = 1 - (0.36 + 0.32) = 0.32\) g.
4. Determine the percentage of hydrogen:
   • Calculate percentage: \(\text{Percentage of H} = \left(\frac{0.32}{1}\right) \times 100 = 4\%.\)

Therefore, the percentage of hydrogen in the compound is 4%.