Types de réactions basiques associées aux composés covalents binaires

1. Types of Chemical Reactions
Special Cases of Synthesis &
Decomposition
We know the basics, but how about
the specifics?

2. Special Types of Synthesis Reactions
Metals
• Metal + Oxygen → Metal oxide
– 4Na(s) + O2(g) → 2Na2O(s)
– 2Mg(s) + O2(g) → 2MgO(s)
• Metal + Sulfur → Metal Sulfide
– Why the same?
• Metal Oxide + Water → Metal Hydroxide
– Na2O(s) + H2O(l) → 2NaOH(aq)
– MgO(s) + H2O(l) → Mg(OH)2(aq)

3. Special Types of Synthesis Reactions
Nonmetals
• Non-metals will react with oxygen to form non-
metal oxides:
– S8(s) + 8O2(g) → 8SO2(g)
– C(s) + O2(g) → CO2(g)
• Non-metals will also react with Cl2 or Br2 to form
chlorides or bromides
– P4(s) + 6 Br2(l) → 4 PBr3(l)
• Non-metal oxides react with water to form
oxyacids:
– SO2(g) + H2O(l) → H2SO3(aq)

4. Reactions of Metals with Halogens
• Mg(s) + Cl2(g) → MgCl2(s)
– This referred to as an oxidation-reduction
(REDOX) reaction
– Why?
– Magnesium is oxidized (electrons are lost)
– Chlorine is reduced (electrons are gained)
– Cl2 causes Mg to be oxidized and is called the
oxidizing agent
– Mg causes Cl2 to be reduced and is the reducing
agent

5. Decomposition Reactions of Metals
• Metal Carbonates (+ heat) → Metal Oxide + CO2(g)
– CaCO3 → CaO(s) + CO2(g)
• Metal Hydroxides (+ heat) → Metal Oxide + H2O(l)
– Ca(OH)2 → CaO + H2O
– Does not happen for Group I hydroxides

6. Decomposition Reactions of Metals
• Metal Chlorates (+ heat) → Metal Chloride + O2(g)
– 2 KClO3(s) → 2 KCl(s) + 3 O2(g)
– This reaction takes place with a catalyst (a substance
added to speed up reaction that is not changed)
• Metal Nitrates (+ heat) → Metal Nitrite + O2(g)
– 2 NaNO3 → 2 NaNO2 + O2(g)
• Hydrogen Peroxide (+ catalyst) → H2O(l) + O2(g)