Topic: Thermodynamics
In order to burn 1 Kg of $CH_{4}$ completely the minimum under of kilograms of Oxygen needed is (take atomic weight of H,C,O as 1,12,16 respectively)
- A. 3
- B. 6
- C. 5
- D. 4
Answer: D. 4
Explanation: Chemical reaction: $CH_{4} + 2O_{2} \rightarrow CO_{2} + 2H_{2}O$. Molecular weight of $CH_{4} = 12 + 4(1) = 16$. Molecular weight of $2O_{2} = 2 \times (16 \times 2) = 64$. 16 kg of $CH_{4}$ needs 64 kg of oxygen. So, 1 kg of $CH_{4}$ requires $64/16 = 4$ kg of $O_{2}$.