Calculate the mass and amount of oxygen reacted with copper if 4g of copper oxide (||) is formed.

The equation for the reaction of copper with oxygen will look like this:

2Cu + O2 = 2CuO.

It can be seen from the equation that 1 mole of oxygen enters the reaction to form 2 mole of copper oxide.

Accordingly, the molar mass will be:

M (O2) = 32 g / mol.

M (2CuO) = 2 x 80 = 160 g / mol.

Find the mass of oxygen by the formula:

m1 • M1 = m2 • M2.

m1 (О2) = m2 • М1 / М2 = 4 • 32/160 = 0.8 g.

We find the number of moles of oxygen by the formula:

n (О2) = m / M.

n (O2) = 0.8 / 32 = 0.025 mol.