Reaction of oxides with water

Question 1

Which oxides are insoluble?

Answer 1

• aluminium and silicon oxide
• therefore they dont react

Question 2

Which oxides are basic?

Answer 2

• sodium and magnesium oxides

Question 3

What happens when Na₂O reacts with water?

Answer 3

• gives a sodium hydroxide solution
  
  • strongly alkaline
• → 2Na²⁺ (aq) + 2OH^- (aq)

Question 4

What happens when MgO reacts with water?

Answer 4

• gives magnesium hydroxide
• sparingly soluble
• soemwhat alkaline
• → Mg(OH)₂ (s) ⇌ Mg²⁺ (aq) + 2OH^-(aq)

Question 5

What elements in period 3 are acidic oxides?

Answer 5

• non-metals on the right of the Periodic Table typically form acidic oxides

Question 6

What happens when P₄O₁₀ reacts with water? Wgat are the equations

draw them if necessary

Answer 6

• reacts quite violently with water to produce and acidic solution of phosphoric(V) acid
• this ionises, so the soln is acidic
• P₄O₁₀ (s) + 6H₂O (l) → 4H₃PO₄ (aq)
• H₃PO₄ (aq) ⇌ H+ (aq) + H₂PO₄^- (aq)

Question 7

What happens when sulfur dioxide reacts with water?

Answer 7

• it is fairly soluble and reacts with water to give an acidic solution of sulfuric(IV) acid (sulfurous acid)
• partially dissociated producing H⁺
• SO₂ (g) + H₂O (l) → H₂SO₃ (aq)
• H₂SO₃ (aq) ⇌ H⁺ (aq) + HSO₃^- (aq)

Question 8

How does sulfur trioxide react with water?

Answer 8

• reacts violently with water to produce sulfuric acid (sulfuric(VI) acid)
• →H₂SO₄ (aq) → H⁺ (aq) + HSO₄ (aq)

Question 9

What is the ovarall patern of the acidity of oxides going across the period?

Answer 9

become more acidic

Question 10

Why are the metal oxides acidic?

Answer 10

• composed of ions
• contain oxide ion
  
  • very strong base (attracts protons)
• readily reeacts with water to produce hydroxide ions a strongly alkaline solution
• magnesium less alkaline because it is less soluble

Question 11

Why are the insoluble oxides insoluble

Answer 11

• bonding in aluminium oxide is too strong for ions to be separated
  
  • partially due to the additional covalent bond
• silicon dioxide is giant macromolecular and water will not affect this type of structure

Question 12

Why do phosphorus oxides and sulfur oxides form acd solution

Answer 12

covalent molecule react with water to form acidic solutions