How to write the balanced equation?

Question

If 3.30g of Cu(NO₃)₂ is obtained from allowing 1.86g of Cu to react with excess HNO₃, what is the percent yield of the reaction? Write the balanced equation.

Answer 1

First determine a balanced equation for the reaction (clue: H2 is produced)

 

From balanced equation determine theoretical gm Cu(NO3)2 produced using unit cancellation:

 

Theoretical gm Cu(NO3)2 = (gm Cu / gm/mol Cu) x (mol Cu(NO3)2 / mol Cu) x gm/mol Cu(NO3)2

 

pct yield = 100 x actual gm Cu(NO3)2 / theoretical Cu(NO3)2