According to the reaction between hydrogen and chlorine to produce hydrochloric acid (HCl), the balanced chemical equation is:
\[ H_2 + Cl_2 \rightarrow 2HCl \]
This means that 1 molecule of \(H_2\) reacts with 1 molecule of \(Cl_2\) to produce 2 molecules of \(HCl\).
In your scenario, we have 20 atoms of hydrogen. Since hydrogen exists as diatomic molecules (\(H_2\)), to find out how many molecules of \(H_2\) correspond to 20 atoms, you can calculate:
\[ \text{Number of } H_2 \text{ molecules} = \frac{20 \text{ atoms of } H}{2 \text{ atoms per molecule}} = 10 \text{ molecules of } H_2 \]
According to the balanced equation, 10 molecules of \(H_2\) will react with 10 molecules of \(Cl_2\) to produce 20 molecules of \(HCl\).
Next, we convert the molecules of chlorine \( (Cl_2) \) to atoms. Each molecule of \(Cl_2\) consists of 2 chlorine atoms, so:
\[ \text{Number of } Cl \text{ atoms} = 10 \text{ molecules of } Cl_2 \times 2 \text{ atoms per molecule} = 20 \text{ atoms of } Cl \]
Therefore, 20 atoms of chlorine reacted with the hydrogen.