In the combustion of 2.0 g of methane 25 kcal heat is liberated, heat of combustion of methane would be ___________ .

Options

A. 100 Kcal
B. 200 Kcal
C. 300 Kcal
D. 4000 Kcal

Answer

To find the heat of combustion of methane, we can follow these steps:

### Step 1: Determine the molecular mass of methane (CH₄)
The molecular mass of methane is calculated as follows:
- Carbon (C) has an atomic mass of 12 g/mol.
- Hydrogen (H) has an atomic mass of 1 g/mol, and there are 4 hydrogen atoms in methane.

So, the molecular mass of methane (CH₄) is:
\[ \text{Molecular mass of CH₄} = 12 + (4 \times 1) = 12 + 4 = 16 \text{ g/mol} \]

### Step 2: Calculate the heat released per gram of methane
We know that 2.0 g of methane releases 25 kcal of heat. To find the heat released per gram, we divide the total heat by the mass of methane:
\[ \text{Heat released per gram} = \frac{25 \text{ kcal}}{2 \text{ g}} = 12.5 \text{ kcal/g} \]

### Step 3: Calculate the heat released for 16 g of methane
Since the heat of combustion is typically expressed for 1 mole (which is 16 g for methane), we can calculate the total heat released for 16 g of methane:
\[ \text{Heat released for 16 g} = 12.5 \text{ kcal/g} \times 16 \text{ g} = 200 \text{ kcal} \]

### Conclusion
The heat of combustion of methane is therefore:
\[ \text{Heat of combustion of methane} = 200 \text{ kcal} \]

### Final Answer
The heat of combustion of methane would be **200 kcal**.

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