Calculate the mass of ethyl alcohol, which is necessary to obtain 88 g. acetaldehyde.

To solve the problem, let’s write down the data:

С2Н5ОН + CuO = CH3 – COH + Cu + H2O – alcohol oxidation, acetaldehyde is released;
Calculations by formulas:
M (C2H5OH) = 46 g / mol;

M (C2H4O) = 44 g / mol;

Y (C2H4O) = m / M = 88/44 = 2 mol.

Y (C2H5OH) = 2 mol since the amount of substances is 1 mol.

We find the mass of the original substance:
m (C2H5OH) = Y * M = 2 * 46 = 92 g

Answer: you need ethyl alcohol weighing 92 g