Calculate the mass and amount of oxygen reacted with copper if 4 g of mowed copper (II) was formed.

1. Oxygen reacts with copper according to the equation:

2Cu + O2 = 2CuO.

2. Establish the chemical amount of the formed copper (II) oxide:

n (CuO) = m (CuO): M (CuO);

M (CuO) = 64 + 16 = 80 g / mol;

n (CuO) = 4: 80 = 0.05 mol.

3. According to the equation, from one mole of oxygen, two moles of copper oxide are obtained, then the amount of oxygen:

n (O2) = n (CuO): 2 = 0.05: 2 = 0.025 mol.

4. Let’s calculate the mass of oxygen:

m (O2) = n (O2) * M (O2) = 0.025 * 32 = 0.8 g.

Answer: 0.8 g, 0.025 mol.