Calculate the mass of nitric acid that is required for reactions with a portion of copper oxide weighing 8 g.

1. Let’s compose the equation of the chemical reaction:

CuO + 2HNO3 = Cu (NO3) 2 + H2O.

2. Find the chemical amount of copper oxide:

n (CuO) = m (CuO) / M (CuO) = 8 g / 80 g / mol = 0.1 mol.

3. Using the reaction equation, we find the chemical amount, and then the mass of nitric acid:

n (HNO3) = n (CuO) * 2 = 0.1 mol * 2 = 0.2 mol.

m (HNO3) = n (HNO3) * M (HNO3) = 0.2 mol * 63 g / mol = 12.6 g.

Answer: m (HNO3) = 12.6 g.