Question

given a chemical reaction, methane (ch₄) burns in oxygen (o₂) to produce carbon dioxide (co₂) and water (h₂o). which of these represent an unbalanced equation with the correct chemical formulas?

a. ch₄ + o₂ → co₂ + h₂o

b. ch₄+ co₂ → o₂ + h₂o

c. co₂+ h₂o → ch₄+ o₂

d. ch₄ → o₂ + co₂+ h₂o

Explanation:

Step1: Analyze the reaction description

The reaction is methane ($\ce{CH_4}$) burning in oxygen ($\ce{O_2}$) to produce carbon dioxide ($\ce{CO_2}$) and water ($\ce{H_2O}$). So the reactants should be $\ce{CH_4}$ and $\ce{O_2}$, and products should be $\ce{CO_2}$ and $\ce{H_2O}$.

Step2: Evaluate each option

• Option A: Reactants are $\ce{CH_4}$ and $\ce{O_2}$, products are $\ce{CO_2}$ and $\ce{H_2O}$. The formulas are correct, and it's unbalanced (check atoms: C:1 on left, 1 on right; H:4 on left, 2 on right; O:2 on left, 3 on right).
• Option B: Reactants are $\ce{CH_4}$ and $\ce{CO_2}$, which is incorrect as per the reaction description (oxygen should be a reactant, not carbon dioxide).
• Option C: Reactants are $\ce{CO_2}$ and $\ce{H_2O}$, products are $\ce{CH_4}$ and $\ce{O_2}$, which is the reverse of the combustion reaction, incorrect reactants/products.
• Option D: Reactant is only $\ce{CH_4}$, but combustion needs $\ce{O_2}$ as a reactant, so incorrect.

Answer:

A. $\ce{CH_{4} + O_{2}
ightarrow CO_{2} + H_{2}O}$