Unit 10 - Acids & Bases

Acids

• Hydrochloric acid - HCl

• Nitric acid - HNO3

• Sulphuric acid - H2SO4

• Phosphoric acid - H3PO4

Real-life examples:

• Vinegar - acetic acid

• Lemon Juice - citric acid

• Tea - tannic acid

• Ant sting/venom - formic acid

Properties of Acids

• Acids produce H+ ions when dissolved in water

• Acids are sour in taste

• Proton donor

Monobasic, Dibasic and Tribasic Acids

• Monobasic acids produce 1 H+ ion

• Dibasic acids produce 2 H+ ions

• Tribasic acids produce 3 H+ ions

• Examples:

• HCl → H+ + Cl- (monobasic)

• HNO3 → H+ + NO3- (monobasic)

• H2SO4 → 2H+ + SO4- (dibasic)

• H3PO4 → 3H+ + PO4- (tribasic)

Bases

• Sodium hydroxide - NaOH

• Potassium hydroxide - KOH

• Magnesium hydroxide - Mg(OH)2

• Ammonia - NH3

Real-life examples:

• Baking soda - sodium bicarbonate

• Toothpaste - sodium fluoride

• Detergent - sodium carbonate

• Soap - sodium hydroxide

Properties of bases

• Bases produce OH- ions

• Bases are bitter in taste

• Soapy or slippery in touch

• Proton acceptor

• Bases that dissolve in water are called alkalies

Bronsted-Lowry Theory: Acids & Bases

• Acid - Proton donor

  • HCl donates a proton to H2O

• Base - Proton acceptor

  • NH3 accepts a proton from H2O

Chemical Properties

Acids Reaction with Metals:

• Acid + Metal ——> Salt + Hydrogen gas

  • Mg + H2SO4 ———> MgSO4 + H2

Acids Reaction with Metal Carbonate:

• Acid + Metal Carbonate ———> Salt + Carbon Dioxide + Water

  • Na2CO3 + H2SO4 ———> Na2SO4 + CO2 + H2O

Acids Reaction with Metal Oxide:

• Acid + Metal Oxide ———> Salt + Water

  • CaO + H2SO4 ———> CaSO4 + H2O

Bases Reaction with Ammonia Salts:

• Base + Ammonia Salts ———> Salts + Ammonia + Water

  • NaOH + NH4Cl ———> NaCl + NH3 + H2O

Oxides

Metallic Oxides:

• Basic Oxides - Na2O, CaO, CuO

  • when metal combines with oxygen

  • reacts with acid - forms salt and water

  • dissolved in water - basic solution, high pH

• Amphoteric - ZnO, Al2O3, PbO, SnO

  • can react with both acid and base

Non-metallic Oxides:

• Acidic Oxides - CO2, SO2, NO2, SiO2

  • when non-metal combines with oxygen

  • reacts with base - forms salt and water

  • dissolved in water - acidic solution, low pH

• Neutral Oxides - H2O, O2, N2O, NO, CO

  • do not react with acids or base

End of Chapter