CHEMICAL REACTIONSPART IV METAL REPLACEMENT Hydrogen gas is

CHEMICAL REACTIONS-PART IV: METAL REPLACEMENT Hydrogen gas is liberated when metals with Eo values greater than hydrogen react with acids. Consult the table of E° values (replacement series) following Part V I. Zn(s) HCI(aq) ZnCl2(aq) +Ha 3. Mg(s)H3PO4 Map04-

Solution

1.

Zn + 2 HCl --> ZnCl₂ + H₂

Zn²⁺ + 2e Zn(s)          E^o = 0.76 V

2.

Ca + H₂SO₄ --> CaSO₄ + H₂

Ca²⁺ + 2e Ca(s)          E^o = 2.87 V

3.

3 Mg + 2 H₃PO₄ --> Mg₃(PO₄)₂ + 3 H₂

Mg²⁺ + 2e Mg(s)       E^o = 2.37 V

Since, Mg, Zn, Ca are placed higher in E^o values than hydrogen, they react with acids to evolve hydrogen gas.