what amout of zinc will be required to generate sufficient hydrogen to completely combined with oxygen obtained by complete decomposition of 30 g of potassium clorate?
2KClO3 ==> 2KCl + 3O2
Convert 30g KClO3 to mols. mols = grams/molar mass.
Using the coefficients in the balanced equation, convert mols KClO3 to mols O2.
2H2 + O2 ==> 2H2O
Using the coefficients in the H2O equation, convert mols O2 from KClO3 reaction to mols H2.
Zn + 2HCl ==> ZnCl2 + H2
Using the coefficient in the Zn equation, convert mols H2 from the H2O equation to mols Zn.
You want to know grams Zn; therefore mols Zn x atomic mass Zn = grams Zn.