Chapter EH, Problem 2R

Solution

Interpretation: The balanced equation for the reaction between hydrogen and oxygen gas needs to be determined.

Concept Introduction: A chemical reaction is said to be balanced if there are an equal number of the same atoms on both sides of the reaction arrow.

  ${\text{2H}}_2\left(g\right)+{\text{O}}_2\left(g\right)\to 2{\text{H}}_{\text{2}}\text{O}\left(l\right)$

According to the question, hydrogen and oxygen gas react in a fuel cell. The reaction can be represented as follows:

  ${\text{H}}_2+{\text{O}}_2\to {\text{H}}_{\text{2}}\text{O}$

Here, hydrogen and oxygen are in a gaseous state, and water so formed is in a liquid state.

Thus,

  ${\text{H}}_2\left(g\right)+{\text{O}}_2\left(g\right)\to {\text{H}}_{\text{2}}\text{O}\left(l\right)$

The above equation can be balanced by giving coefficient 2 to ${\text{H}}_{\text{2}}\text{O}\left(l\right)$ .

  ${\text{H}}_2\left(g\right)+{\text{O}}_2\left(g\right)\to 2{\text{H}}_{\text{2}}\text{O}\left(l\right)$

Now, give coefficient 2 to ${\text{H}}_2\left(g\right)$ to balance the number of H and O atoms.

  ${\text{2H}}_2\left(g\right)+{\text{O}}_2\left(g\right)\to 2{\text{H}}_{\text{2}}\text{O}\left(l\right)$

Thus, the balanced chemical equation is represented as follows:

  ${\text{2H}}_2\left(g\right)+{\text{O}}_2\left(g\right)\to 2{\text{H}}_{\text{2}}\text{O}\left(l\right)$