Posted by
**Carter** on
.

I cannot figure out how to work this stoichiometry problem with the given equation: Mg+2HCl-->MgCl2+H2

What volume of hydrogen is produced from the reaction of 50.0g of Mg and the equivalent of 75g of HCl

What do you not understand about it?

It is a limiting reagent problem? Either Mg or HCl will not be completely consumed in the reaction.

Yes. It is a limiting reactant problem. I cannot figure out how you figure out the volume of hydrogen that is produced.

Two ways to do it. The one I like, which takes more time but is easier for me to explain, works this way.

Change g Mg and and g HCl to mols.

mols = g/molar mass.

Convert mols Mg and mols HCl, in two separate steps, to mols H2 produced. Use the coefficients in the balanced equation as usual for this part of the stoichiometry.

The numbers will not be the same. The smaller one (it's always the smaller one) is the one you take. That one, whichever it is; i.e., HCl or Mg, is the limiting reagent and the OTHER one will not be consumed entirely (that is it is the one in excess). See if you can take it from here. Post your work if you get stuck and I can help you through it.