Question

produsul obtinut la arderea a 8 g. de sulf a fost trecut prin 200 g , solutie de hidrixid de sodiu cu partea de masa 20 % , calculeaza masa sarii formate

Answer 1

n = m/M = 8/32 = 0.25 moli S

S + O₂ ⇒ SO₂

n S = nSO₂ = 0,25 moli

C = md/ms×100 ⇒ md = C*ms/100 = 20*200/100 = 40g NaOH

n = m/M = 40/40 = 1 mol NaOH

1 mol...2 moli
SO₂ + 2NaOH  ⇒ Na₂SO₃ + H₂O
0,25 moli....x = 0,5 moli

1 mol SO₂.........2 moli NaOH
x = 0,5 moli..........1 mol NaOH 

n NaOH  exces = 1-0,5 = 0,5  moli => 20g NaOH

1 mol SO₂....................126g Na₂SO₃
0,25 moli SO₂..............x = 31,5g Na₂SO₃

MNa₂SO₃ = 126g/mol