posted by fru .
A small piece of zinc is dissolved in 22.29 mL of 0.968 M HCl.
Zn (s) + 2 HCl (aq) ----> ZnCl2 (aq) + H2 (g)
At the end of the reaction, the concentration of the 22.29-mL sample is redetermined and found to be 0.691 M HCl.
What must have been the mass of the piece of zinc that dissolved?
1. Calculate mols HCl initially.
mols = M x L.
2. Calculate mols HCl at the end of the reaction.
3. Subtract and that is mols HCl used.
4. Using the coefficients in the balanced equation, convert mols HCl to mols Zn.
5. Convert mols Zn to grams Zn.
mols x molar mass = grams.
Post your work if you get stuck.