0.197 g of a substance when heated with strong nitric acid and silver nitrate gave 0.3525 g of silver iodine. Percentage of iodine is

Options

A. 95
B. 96.7
C. 95.5
D. 98.05

Explanation

To find the percentage of iodine in the given substance, we can follow these steps:

### Step 1: Determine the molar mass of silver iodide (AgI)
The molar mass of silver iodide (AgI) can be calculated using the atomic masses of silver (Ag) and iodine (I):
- Atomic mass of Ag = 107.87 g/mol
- Atomic mass of I = 126.90 g/mol

Molar mass of AgI = Atomic mass of Ag + Atomic mass of I
= 107.87 g/mol + 126.90 g/mol
= 234.77 g/mol

### Step 2: Calculate the number of moles of silver iodide (AgI) produced
Using the mass of silver iodide produced (0.3525 g), we can find the number of moles of AgI:
Number of moles of AgI = Mass of AgI / Molar mass of AgI
= 0.3525 g / 234.77 g/mol
≈ 0.0015 mol

### Step 3: Determine the mass of iodine in the silver iodide
Since 1 mole of AgI contains 1 mole of iodine, the number of moles of iodine is the same as the number of moles of AgI. Now, we can calculate the mass of iodine:
Mass of Iodine = Number of moles of Iodine × Atomic mass of I
= 0.0015 mol × 126.90 g/mol
≈ 0.19035 g

### Step 4: Calculate the percentage of iodine in the original substance
To find the percentage of iodine in the original substance, we use the formula:
Percentage of Iodine = (Mass of Iodine / Mass of Substance) × 100
= (0.19035 g / 0.197 g) × 100
≈ 96.7%

### Final Result
The percentage of iodine in the substance is approximately **96.7%**.

---