4.
Al → Al₂O₃ → AlCl₃ → Al(OH)₃ → Al₂O₃ → Al
1) 4Al + 3O₂ = 2Al₂O₃
2) Al₂O₃ + 6HCl = 2AlCl₃ + 3H₂O
3) AlCl₃ + 3NaOH = 3NaCl + Al(OH)₃↓
4) 2Al(OH)₃ →t°→ Al₂O₃ + 3H₂O
5) 2Al₂O₃(электролиз) → 4Al + 3O₂
5.
CuO + 2 HNO₃ = Cu(NO₃)₂ + H₂O
M(CuO) = 80 г/моль
n(CuO) = m(CuO) ÷ M(CuO) = 20 ÷ 80 = 0,25
n(Cu(NO₃)₂) = n(CuO) = 0,25 моль
M(Cu(NO₃)₂) = 188 г/моль
m(Cu(NO₃)₂) = n(Cu(NO₃)₂) × M(Cu(NO₃)₂) = 0,25 × 188 = 47 г
4.
Al → Al₂O₃ → AlCl₃ → Al(OH)₃ → Al₂O₃ → Al
1) 4Al + 3O₂ = 2Al₂O₃
2) Al₂O₃ + 6HCl = 2AlCl₃ + 3H₂O
3) AlCl₃ + 3NaOH = 3NaCl + Al(OH)₃↓
4) 2Al(OH)₃ →t°→ Al₂O₃ + 3H₂O
5) 2Al₂O₃(электролиз) → 4Al + 3O₂
5.
CuO + 2 HNO₃ = Cu(NO₃)₂ + H₂O
M(CuO) = 80 г/моль
n(CuO) = m(CuO) ÷ M(CuO) = 20 ÷ 80 = 0,25
n(Cu(NO₃)₂) = n(CuO) = 0,25 моль
M(Cu(NO₃)₂) = 188 г/моль
m(Cu(NO₃)₂) = n(Cu(NO₃)₂) × M(Cu(NO₃)₂) = 0,25 × 188 = 47 г