A 0.411 g sample of powdered copper mixed with an inert, soluble additive was fully consumed by 23.4mL of 0.602M nitric acid, producing copper (II) nitrate, water, and nitric oxide. What is the percent copper by mass in the sample?

Question

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

Answer 1

Dear Veronica,
number of moles of HNO3 used=
0.602x(23.4/1000)
= 0.014
number of mol of Cu used=
0.014/8x3
=5.28255x10^-3

mass of the Cu involved in the reaction
= 5.28255x10^-3 x 63.5
= 0.33544g

%by mass of Cu =
0.33544/0.411 x 100%
= 81.6%