GIVEN THE FOLLOWING CHEMICAL EQUATION:

Question

3 +Cu +8 HNO3 = 3 Cu(NO3)2 + 2 NO + 4 H2O.

1).HOW MANY MOLES OF Cu(NO3)2 ARE PRODUCED WHEN 3 MOLES OF Cu REACT?

2).HOW MANY MOLES OF Cu MUST REACT TO PRODUCE 4 MOLES OF NO?

3). If 4 moles of NO ARE PRODUCED HOW MANY MOLES OF h2o are also produced?

Answer 1

You let the coefficients in the balanced equation tell you the answer.
For #1.
mols Cu(NO3)2 = mols Cu x (3 mols Cu(NO3)2/3 mols Cu) = 3 x 3/3 = 3.

For #2.
mols Cu = mols NO x (3 mols Cu/4 mols NO) = 4 mols NO x 3/4 = 3 mols Cu.
Note how the factor used converts what we have to what we want (in the first example what we have is 3 mols Cu and what we want is mols Cu(NO3)3. In the second example, what we have is 4 mols NO and what we want is mols Cu.
The third one is done the same way. This is the same as the problem you posted earlier; however, this is the systematic way of doing it.
Check my work carefully.