Question

what is the chemical equation for the burning of propane if all the products and reactants are in the gas phase? 4h₂o(g) + 3co₂(g) + 5o₂(g) → c₃h₈(g) c₃h₈(g) + 5o₂(g) → 3co₂(g) + 4h₂o(g) c₃h₈(g) + o₁₀(g) → 3co₂(g) + 4h₂o(l) 4h₂o(l) + 3co₂(g) → c₃h₈(g) + 5o₂(g)

Explanation:

Burning (combustion) of a hydrocarbon like propane ($\ce{C3H8}$) reacts with oxygen ($\ce{O2}$) to produce carbon dioxide ($\ce{CO2}$) and water. The reaction should have reactants as propane and oxygen, products as $\ce{CO2}$ and $\ce{H2O}$ (gas phase here). Let's analyze each option:

• First option: Reactants and products are reversed (shows products as reactants and vice versa), incorrect.
• Second option: Reactants are $\ce{C3H8(g)}$ and $\ce{5O2(g)}$, products are $\ce{3CO2(g)}$ and $\ce{4H2O(g)}$ (gas phase), and the equation is balanced (C: 3 on both, H: 8 on both, O: 10 on both).
• Third option: Oxygen is written as $\ce{O10}$ (incorrect formula, oxygen is $\ce{O2}$) and water is liquid, not gas, incorrect.
• Fourth option: Reactants and products are reversed (like a reverse reaction, not combustion) and water is liquid, incorrect.

Answer:

B. $\ce{C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(g)}$