Given the following equation: Mg(s)+2HCl(aq) goes to MgCl2(s)+H2(g)

Question

How many grams of hydrogen chloride (HCl) are needed to produce 200g of hydrogen H2?

Answer 1

Here is a sample stoichiometry problem work out for you. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html
Post your work if you get stuck.