Question

Calculate the amount of 6 M nitric acid you need to add to fully react with .5 grams of copper and add a 20 percent excess.

Answer 1

Here is a worked example of a stoichiometry problem such as this. After finding moles HNO3, the M = moles/L will give you volume HNO3, then add 20% excess to that.
http://www.jiskha.com/science/chemistry/stoichiometry.html

Answer 2

I still do not understand.

Answer 3

You haven't had time to try yet. Follow the steps one by one. Those instructions, which I wrote, will take you to the answer.
The equation is
3Cu + 8HNO3 ==>3Cu(NO3)2 + 2NO + 4H2O
Check that to make sure it is balanced.

Answer 4

It still doesnt make aense because the answer comes out to 240 liters.

Answer 5

That's not a balanced equation. It should be Cu + 4HNO3 ==>Cu(NO3)2 + 2NO + 2H2O