Question

Use the chemical reaction to answer the question.

2H2+O2→2H2O


There are four atoms of hydrogen ( H
) before the reaction. How many atoms of hydrogen are present after the reaction?

Answer 1

In the chemical reaction:

\[ 2H_2 + O_2 \rightarrow 2H_2O \]

We can break it down as follows:

- On the left side of the equation, there are 2 molecules of \( H_2 \), and each \( H_2 \) molecule contains 2 hydrogen atoms. Therefore, the total number of hydrogen atoms before the reaction is:

\[ 2 \, \text{molecules} \times 2 \, \text{atoms/molecule} = 4 \, \text{atoms of H} \]

- On the right side of the equation, there are 2 molecules of \( H_2O \), and each \( H_2O \) molecule contains 2 hydrogen atoms. Therefore, the total number of hydrogen atoms after the reaction is:

\[ 2 \, \text{molecules} \times 2 \, \text{atoms/molecule} = 4 \, \text{atoms of H} \]

Thus, there are 4 atoms of hydrogen present after the reaction as well. The number of hydrogen atoms remains the same before and after the reaction.