Again, 1 mole of H2 reacting with 1 mole of Cl2 produces 2 moles of HCl, you can see this from the balanced equation. It's a mathematical ratio. For every mole of H2, assuming you have enough Cl2 to react with it, you can produce 2 moles of HCl.
So the reaction we are considering is: H2 + Cl2 --> 2HCl
Remember how the coefficients of the species involved in the reaction represent mole ratios of the products and reactants. So for example, here in this equation we can see how 1 mole of H2 reacting with 1 mol of Cl2 produces 2 moles of HCl.
If it helps, you can visualize this as one H2 molecule and one Cl2 molecule separating into 2 H atoms and 2 Cl atoms respectively, and then the H and Cl atoms combining to form 2 HCl molecules. This essentially represents what is going on at a larger scale, with 1 mol of H2 and 1 mol of Cl2 producing 2 moles of HCl, where a mole is just a unit of measurement representing 6.022*10^23 particles.
Again, 1 mole of H2 reacting with 1 mole of Cl2 produces 2 moles of HCl, you can see this from the balanced equation. It's a mathematical ratio. For every mole of H2, assuming you have enough Cl2 to react with it, you can produce 2 moles of HCl.
So the reaction we are considering is: H2 + Cl2 --> 2HCl
Remember how the coefficients of the species involved in the reaction represent mole ratios of the products and reactants. So for example, here in this equation we can see how 1 mole of H2 reacting with 1 mol of Cl2 produces 2 moles of HCl.
If it helps, you can visualize this as one H2 molecule and one Cl2 molecule separating into 2 H atoms and 2 Cl atoms respectively, and then the H and Cl atoms combining to form 2 HCl molecules. This essentially represents what is going on at a larger scale, with 1 mol of H2 and 1 mol of Cl2 producing 2 moles of HCl, where a mole is just a unit of measurement representing 6.022*10^23 particles.