2H2 + O2 -> 2H2O

Question

there are four atoms of hydrogen before the reaction. how many atoms of hydrogen are present after the reaction?

Answer 1

In the reaction \(2H_2 + O_2 \rightarrow 2H_2O\), you start with 4 hydrogen atoms (from the \(2H_2\) molecules).

After the reaction, the products are \(2H_2O\). Each water molecule (\(H_2O\)) contains 2 hydrogen atoms. Since there are 2 water molecules produced, the total number of hydrogen atoms after the reaction is:

\[ 2 \text{ H}_2O \times 2 \text{ H atoms per molecule} = 4 \text{ H atoms} \]

So, there are 4 hydrogen atoms present after the reaction, which is the same number as before the reaction.