Question

consider these intermediate chemical equations.
ch₄(g) + 2o₂(g) → co₂(g) + 2h₂o(g)
2h₂o(g) → 2h₂o(l)
which overall chemical equation is obtained by combining these intermediate equations?

ch₄(g) + 2o₂(g) → co₂(g) + 4h₂o(g) + 2h₂o(l)

ch₄(g) + 2o₂(g) → co₂(g) + 2h₂o(l)

ch₄(g) + 2o₂(g) → co₂(g) + 6h₂o(g)

ch₄(g) + 2o₂(g) → co₂(g) + 2h₂o(g)

Explanation:

Step1: Identify common species

The first equation is $\mathrm{CH}_{4}(g)+2\mathrm{O}_{2}(g)
ightarrow\mathrm{CO}_{2}(g)+2\mathrm{H}_{2}\mathrm{O}(g)$. The second equation is $2\mathrm{H}_{2}\mathrm{O}(g)
ightarrow2\mathrm{H}_{2}\mathrm{O}(l)$.

Step2: Combine equations

When we combine them, the $2\mathrm{H}_{2}\mathrm{O}(g)$ in the first - equation and the $2\mathrm{H}_{2}\mathrm{O}(g)$ in the second - equation cancel out.

Answer:

$\mathrm{CH}_{4}(g)+2\mathrm{O}_{2}(g)
ightarrow\mathrm{CO}_{2}(g)+2\mathrm{H}_{2}\mathrm{O}(l)$