please help me please i have been stuck for many hours

Question

Question 1: 3 Cu  +   8HNO₃   g 3 Cu(NO₃)₂   +  2 NO  +  4  H₂O

In the above equation how many moles of NO can be made when 60 moles of HNO₃ are consumed?



Question 2: 2 NH₃  +  3 CuO   g  3 Cu  +  N₂  +   3 H₂O

In the above equation how many moles of water can be made when 79 moles of NH₃ are consumed?

Question 3: S   +   6 HNO₃  -->  H₂SO₄  +  6 NO₂  +   2 H₂O

In the above equation how many moles of water can be made when 47 moles of HNO₃ are consumed?

Please give and only give explanation and solution please.

Answer 1

Solutions:

Question 1: 15 moles NO (20 moles NO for 1 sig fig)

Question 2: 119 moles H2O (120 moles H2O for 2 sig figs)

Question 3: 15.7 moles H2O (16 moles H2O for 2 sig figs)

Explanations:

Question 1:

The question essentially calls to convert the 60 moles of HNO3 into moles of NO.

You would therefore need a conversion factor, or in this case the molar ratio, between HNO3 and NO. This comes from the coefficients in the chemical equation. The coefficients for HNO3 and NO are 8 and 2, respectively - giving you a molar ratio between HNO3 : NO = 8 : 2. The units in the chemical equations can be in moles for a molar ratio of (8 moles HNO3) : (2 moles NO).

Now that you have the molar ratio, you can use multiply with them as a fraction:

60 moles of HNO3 × (2 moles NO)/(8 moles HNO3) = 15 moles of NO

Question 2:

Using a similar process in question 1, the question essentially calls to convert the 79 moles of NH3 into moles of H2O.

The molar ratio in this case is (2 moles NH3) : (3 moles H2O)

79 moles of NH3 × (3 moles H2O)/(2 moles NH3) = 120 moles of NO

Question 3:

Using a similar process in question 1, the question essentially calls to convert the 47 moles of HNO3 into moles of H2O.

The molar ratio in this case is (2 moles H2O) : (6 moles HNO3)

47 moles of HNO3 × (2 moles H2O)/(6 moles HNO3) = 16 moles of NO