
Peter M. answered 05/06/21
Organic Chemistry PhD Student Tutoring For Over 6 Years!
3 Cu + 8 HNO3 --> 3 Cu(NO3)2 + 2 NO + 4 H2O
We want to calculate the number of moles of water produced when reacting with 25 moles of HNO3. In order to do this, we can use the mole ratio that is given to us by the balanced chemical equation. These are the coefficients in front of each specie in the equation. The only thing to take into account is that units that are diagonal from each other when multiplying cancel.
25 mol HNO3 * (4 mol H2O / 8 mol HNO3) = 12.5 mol H2O
2 NaClO3 ---> 2 NaCl + 3 O2
The same explanation applies. If we want to make 44 moles of O2, then we just start with that and use the ratio, cancelling along the diagonal, and multiplying to get our answer.
44 mol O2 * (2 mol NaClO3 / 3 mol O2) = 29.33 mol NaClO3