Calculate and note the mass fraction of etanoic acid in a solution weighing 150 g
Calculate and note the mass fraction of etanoic acid in a solution weighing 150 g, if a sodium hydroxide solution weighing 250 g with a mass fraction of alkali of 16% was spent on its neutralization.
1. Let’s write down the equality of chemical interaction:
CH3COOH + NaOH = CH3COONa + H2O.
2. Find the chemical number of sodium hydroxide:
m (NaOH) = m (solution) * ω (NaOH) / 100% = 250 g * 16% / 100% = 40 g.
n (NaOH) = m (NaOH) / M (NaOH) = 40 g / 40 g / mol = 1 mol.
3. Based on the equality of the chemical interaction, we find the chemical number and, as a result, the mass fraction of acetic acid:
n (CH3COOH) = n (NaOH) = 1 mol.
m (CH3COOH) = n (CH3COOH) * M (CH3COOH) = 1 mol * 60 g / mol = 60 g.
ω (CH3COOH) = m (CH3COOH) / m (solution) * 100% = 60 g / 150 g * 100% = 40%.
Answer: ω (CH3COOH) 40%.