Ca -> CaO -> Ca(OH)2 -> CaSO4 ->H2SO4 -> Na2SO4 -> Na3PO4 -> Fe(NO3)2 -> FeCl3 -> KCl -> HCl

Сa⇒CaO⇒Ca(OH)₂⇒CaSO₄⇒H₂SO₄⇒Na₂SO₄⇒Na₃PO₄⇒Fe(NO₃)₂⇒FeCl₃⇒
⇒KCl⇒HCl
2Сa +O₂=2CaO
CaO + H₂O=Ca(OH)₂↓
Ca(OH)₂ +H₂SO₄=CaSO₄ + H₂O

CaS +  3CaSO₄= 4CaO +4SO₂
2SO₂ +O₂=2SO₃
SO₃+H₂O=H₂SO₄

H₂SO₄+ 2NaOH=Na₂SO₄ +H₂O

Na₂SO₄≠Na₃PO₄
Na₃PO₄≠Fe(NO₃)₂
Fe(NO₃)₂≠FeCl₃

FeCl₃ + 3KOH = 3KCl + Fe(OH)₃↓
2KCl + H₂SO₄=K₂SO₄+ 2HCl