What mass of hydrogen gas is produced when 3.0 mol of iron react with excess hydrochloric acid according to the reaction below

2Fe + 6HCl --> 2FeCl3 + 3H2

To calculate the mass of hydrogen gas produced when 3.0 mol of iron react with excess hydrochloric acid, we need to use the stoichiometry of the balanced chemical equation.

The stoichiometry tells us that 2 mol of iron reacts with 6 mol of hydrochloric acid to produce 3 mol of hydrogen gas.

First, we need to calculate the amount of hydrogen gas produced in moles using the given amount of iron (3.0 mol) and the stoichiometry:

3.0 mol iron * (3 mol hydrogen gas / 2 mol iron) = 4.5 mol hydrogen gas

Now, to convert the amount of hydrogen gas from moles to grams, we use the molar mass of hydrogen gas. The molar mass of hydrogen is approximately 1.008 g/mol.

4.5 mol hydrogen gas * 1.008 g/mol = 4.536 g hydrogen gas

Therefore, approximately 4.536 grams of hydrogen gas will be produced when 3.0 mol of iron reacts with excess hydrochloric acid.