What mass of acetaldehyde can be obtained by oxidizing ethanol with a volume of 80 cm3, if the mass fraction of its output is 90%.

To solve, we write down the reaction equation:
1. С2Н5ОН + CuO = CH3COH + Cu + H2O – ethanol oxidation reaction, acetaldehyde obtained;
2. Let’s calculate the molar masses of substances:
M (C2H5OH) = 46 g / mol;
M (CH3COH) = 44 g / mol;
3. Let’s convert cm3 to liters according to ethanol data:
1 cm3 = 0.001 l; 80 cm3 = 0.08 l;
4. Let’s calculate the amount of ethanol mol:
1 mol of gas at n. y – 22.4 l;
X mol С2Н5ОН – 0.08 L. hence, X mol (C2H5OH) = 1 * 0.08 / 22.4 = 0.0036 mol;
According to the equation, the amount of moles of alcohol and aldehyde are equal to 1 mole each, which means that Y (CH3COH) = 0.0036 mole
5. Let’s calculate the theoretical mass of acetaldehyde:
m (theoretical) = Y * M = 0.0036 * 44 = 0.158 g;
6. Determine the practical mass, taking into account the product yield of 90%:
W = m (practical) / m (yelling) * 100;
m (practical) = 0.90 * 0.158 = 0.142 g.
Answer: the mass of acetaldehyde is 0.142 g.