Heating a mixture of ethanol and propionic acid gave 15.3 g of ether. Neutralization of the same amount

| April 29, 2021 | education

Heating a mixture of ethanol and propionic acid gave 15.3 g of ether. Neutralization of the same amount of the mixture requires 38.8 cm ^ 3 of NaOH solution (w = 20% p = 1.22 cm ^ 3). Determine the mass fraction of substances in the original mixture.

1. Reaction between ethanol and propionic acid:
С2Н5ОН + С2Н5СООН = С2Н5СООС2Н5 + Н2О
According to the equation, the amount of ether is equal to the amount of ethanol:
n (C2H5OH) = n (C2H5COOC2H5) = 15.3 / M (C2H5COOC2H5) = 15.3 / 102 = 0.15 mol
Hence, the mass of ethanol in the mixture is
m (C2H5OH) = n (C2H5OH) * M (C2H5OH) = 0.15 * 46 = 6.9 g
2. Neutralization of propionic acid:
CH3CH2COOH + NaOH → CH3CH2COONa + H2O
Alkali mass:
m = ρ * V = 1.22 * 38.8 = 47.3 g
Alkali amount:
n (NaOH) = 47.3 * 0.2 / M (NaOH) = 9.46 / 40 = 0.24 mol
According to the equation, the amount of acid is equal to the amount of alkali:
n (C2H5COOH) = n (NaOH) = 0.24 mol
Acid mass:
m (C2H5COOH) = n (C2H5COOH) * M (C2H5COOH) = 0.24 * 74 = 17.76 g
Mix weight:
mc = 6.9 g + 17.76 g = 24.66 g
Mass fractions are:
Ethanol: 6.9 / 24.66 = 27.9%
Propionic acid: 17.76 / 24.66 = 72.1%
Answer: mass fractions of Ethanol 27.9%, propionic acid 72.1%



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