I think you need to do some work first, before I help.
What is the balanced reaction? you have to write the symbols and compounds correctly: Hint, doing that is likely to give you the answer.
5.74 g of mg reacts with hcl to form mgcl and h .calculate the moles of h from 0.0840 of mg and excess hcl
2 answers
PLEASE learn where the caps key is on your computer and USE it.
Second, your question is confusing. Is that two problems or one? I'll ignore the 5.74 g Mg; I don't know what that has to do with the problem. Now, dealing only with the 0.0840 g Mg (by the way, mg is milligrams and not Mg for magnesium).
Mg + 2HCl --> MgCl2 + H2
mols Mg = grams/atomic mass = ?
Now, look at the coefficients in the balanced equation. 1 molMg will produce 1 mol H2; therefore, mols H2 produced will be the same as mols Mg you started with.
Post your work if you need furthere assistance.
Second, your question is confusing. Is that two problems or one? I'll ignore the 5.74 g Mg; I don't know what that has to do with the problem. Now, dealing only with the 0.0840 g Mg (by the way, mg is milligrams and not Mg for magnesium).
Mg + 2HCl --> MgCl2 + H2
mols Mg = grams/atomic mass = ?
Now, look at the coefficients in the balanced equation. 1 molMg will produce 1 mol H2; therefore, mols H2 produced will be the same as mols Mg you started with.
Post your work if you need furthere assistance.