Дано
m(ppa CH3COOH) = 75 g
W(CH3COOH) = 15%
-----------------------------------
m(NaOH)-?
m(CH3COOH) = 75*15% / 100% = 11.25 g
CH3COOH+NaOH-->CH3COONa+H2O
M(CH3COOH) = 60 g/mol
n(CH3COOH) = m/M = 11.25 / 60 = 0.1875 mol
n(CH3COOH) = n(NaOH) = 0.1875 mol
M(NaOH) = 40 g/mol
m(NaOH) = n*M = 40 * 0.1875 = 7.5 g
ответ 7.5 г