Calculate the mass of the acid obtained by heating 55 g of a 40% ethanal solution with an excess of copper (II) hydroxide.
Let’s write the reaction equation:
CH3COH + 2Cu (OH) 2 → CH3COOH + Cu2O + 2H2O (conditions: temperature; acetic (ethanic) acid, copper (I) oxide).
1) Calculate the mass of the solute – ethanal:
mr.w. (CH3COH) = (mr-pa (CH3COH) * w.w.) / 100% = (55 g * 40%) / 100% = 22 g.
2) Find the amount of ethanal substance:
n (CH3COH) = m (CH3COH) / M (CH3COH) = 22 g / 44 g / mol = 0.5 mol.
Since copper hydroxide is taken in excess, we calculate based on the deficiency – ethanal.
3) Find the amount of acetic acid substance:
n (CH3COOH) = n (CH3COH) = 0.5 mol.
4) Calculate the mass of the acid:
m (CH3COOH) = n (CH3COOH) * M (CH3COOH) = 0.5 mol * 60 g / mol = 30 g.
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