Question

Hòa tan 15,5g Na₂O + H2O -> dung dịch có V =500ml

a) C_M = ?

b) V = ? dung dịch H2SO4 20% (D=1,14 g/ml) để trung hòa dung dịch trên

Answer 1

Na₂O + H₂O → 2NaOH (1)

\(n_{Na_2O}=\frac{15,5}{62}=0,25\left(mol\right)\)

a) Theo pT1: \(n_{NaOH}=2n_{Na_2O}=2\times0,25=0,5\left(mol\right)\)

\(\Rightarrow C_{M_{NaOH}}=\frac{0,5}{0,5}=1\left(M\right)\)

b) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O (2)

Theo pT2: \(n_{H_2SO_4}=\frac{1}{2}n_{NaOH}=\frac{1}{2}\times0,5=0,25\left(mol\right)\)

\(\Rightarrow m_{H_2SO_4}=0,25\times98=24,5\left(g\right)\)

\(\Rightarrow m_{ddH_2SO_4}=\frac{24,5}{20\%}=122,5\left(g\right)\)

\(\Rightarrow V_{ddH_2SO_4}=\frac{122,5}{1,14}=107,46\left(ml\right)\)