Calculate how much copper is required to react with an excess of concentrated nitric acid to produce 4 L of nitric oxide (IV)

Given:
V (NO2) = 4 l

To find:
m (Cu) -?

Decision:
1) Write the equation of a chemical reaction:
Cu + 4HNO3 => Cu (NO3) 2 + 2NO2 ↑ + 2H2O;
2) Calculate the molar mass of Cu:
M (Cu) = Mr (Cu) = Ar (Cu) = 64 g / mol;
3) Calculate the amount of substance NO2:
n (NO2) = V (NO2) / Vm = 4 / 22.4 = 0.18 mol;
4) Determine the amount of Cu substance (taking into account the coefficients in the reaction equation):
n (Cu) = n (NO2) / 2 = 0.18 / 2 = 0.09 mol;
5) Calculate the mass of Cu:
m (Cu) = n (Cu) * M (Cu) = 0.09 * 64 = 5.8 g.

Answer: The mass of Cu is 5.8 g.