Question

How many grams of iron are needed to produce 42.8 L of hydrogen gas according to the following reaction at 25oC and 1 atm?

iron (s) + hydrochloric acid (aq) iron(II) chloride (aq) + hydrogen (g)

Answer 1

Here is a worked example of a stoichiometry problem such as this. Just follow the steps. 42.8L/22.4 = moles H2 gas.
http://www.jiskha.com/science/chemistry/stoichiometry.html