Determine the mass of cuprum (2) oxide, which is formed by the interaction of 6.42 copper with 1.62 mass oxygen.

1. We write down the equation of reactions.
2Cu + O2 = 2CuO.
Find the molar mass of copper.
M (Cu) = 64 g / mol.
Find the molar mass of oxygen.
M (O2) = 2 × 16 = 32 g / mol.
Find the mass of oxygen according to the reaction equation.
6.42 g Cu – x g O2.
2 × 64 g / mol Сu – 32 g / mol О2.
X = 6.42 × 32 ÷ (2 × 64) = 205.44 / 128 = 1.605 g O2.
In fact, oxygen is 1.62, therefore, oxygen is in excess. This means that we find the mass of copper oxide in terms of copper.
M (CuO) = 64 + 16 = 80 g / mol.
6.42 g Cu – X g CuO.
2 × 64 g / mol Cu – 2 × 80 g / mol CuO.
x = 6.42 × 2 × 80 / (2 × 64) = 1027.2 / 128 = 8.025 g.
Answer: the mass of copper oxide is 8.025 g.



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