Properties of Acids and Bases Topic 8.2

But first, a review!

Practice problems Identify the acid, base, conjugate acid, conjugate base, and conjugate acid-base pairs: acidbase conjugate acidconjugate base HC 2 H 3 O 2 (aq) + H 2 O (l)  C 2 H 3 O 2 – (aq) + H 3 O + (aq) conjugate acid-base pairs acidbase conjugate acidconjugate base OH – (aq) + HCO 3 – (aq)  CO 3 2– (aq) + H 2 O (l) conjugate acid-base pairs

acidbase conjugate acidconjugate base HF (aq) + SO 3 2– (aq)  F – (aq) + HSO 3 – (aq) conjugate acid-base pairs acidbase conjugate acidconjugate base CO 3 2– (aq) + HC 2 H 3 O 2 (aq)  C 2 H 3 O 2 – (aq) + HCO 3 – (aq) conjugate acid-base pairs acidbase conjugate acidconjugate base H 3 PO 4 (aq) + OCl – (aq)  H 2 PO 4 – (aq) + HOCl (aq) conjugate acid-base pairs (a) (b) (c)

acidbase conjugate baseconjugate acid HCO 3 – (aq) + S 2– (aq)  HS – (aq) + CO 3 2– (aq) conjugate acid-base pairs baseacid conjugate acidconjugate base H 2 CO 3 (aq) + OH – (aq)  HCO 3 – (aq) + H 2 O (l) conjugate acid-base pairs acidbase conjugate acidconjugate base H 3 O + (aq) + HSO 3 – (aq)  H 2 O (l) + H 2 SO 3 (aq) conjugate acid-base pairs 8a) 8b) 11a) baseacid conjugate baseconjugate acid OH – (aq) + HSO 3 – (aq)  H 2 O (l) + SO 3 2– (aq) conjugate acid-base pairs 11b) For more lessons, visit

Properties of (some) Acids taste sour cool to use in movies corrode metals (produce H 2 gas) react with bases to form a “salt” (ionic compounds that can result from the neutralization reaction of an acid and a base) and water pH is less than 7 turns blue litmus paper to red strong acids are strong electrolytes, weak acids are weak electrolytes

Properties of (some) Bases produce OH - ions in solution (Arrhenius definition) taste bitter feel soapy, slippery dissolve oil and grease react with acids to form a salt and H 2 O pH is greater than 7 turns red litmus paper to blue strong bases are good electrolytes, weak bases weak electrolytes

Bases in Solution a soluble base is called an alkali – when added to water release an OH - ion base(aq) = alkali – K 2 O(s) + H 2 O(l)  2K + (aq) + 2OH - (aq) – NH 3 (aq) + H 2 O(l) ⇌ NH 4 + (aq) + OH - (aq) – CO 3 2- (aq) + H 2 O(l) ⇌ HCO 3 - (aq) + OH - (aq) – HCO 3 - (aq) ⇌ CO 2 (g) + OH - (aq)

The 5 Reactions of Acids “swap the hydrogen for the metal”

ACIDS Salt + Water Salt + Water + CO2 Salt + H2 Salt + Water (NH4)Salt Water METAL (if more reactive than hydrogen) METAL CARBONATE or HYDROGEN CARBONATE (base) METAL HYDROXIDE (base) BASES (without OH) METAL OXIDE (base)

1. Acids reaction with metals most dilute acids react with metals above hydrogen in the reactivity series (Topic 9) to produce H 2 gas and a solution of a salt – in general: reactive metal + acid  “salt” + hydrogen » Mg(s) + 2HCl(aq)  MgCl 2 (aq) + H 2 (g) » Mg(s) + 2HNO 3 (aq)  Mg(NO 3 ) 2 (aq) + H 2 (g) » Mg(s) + H 2 SO 4 (aq)  MgSO 4 (aq) + H 2 (g) » Mg(s) + 2CH 3 COOH(aq)  (CH 3 COO) 2 Mg(aq) + H 2 (g)

Reactivity series (Topic 9)

2. Acid reaction with metal hydroxides acids react to give salt and water when a metal hydroxide(OH) or aqueous ammonia is added in general: – metal hydroxide + acid  “salt” + water NaOH(aq) + HNO 3 (aq)  NaNO 3 (aq) + H 2 O(l) KOH(aq) + H 2 SO 4 (aq)  K 2 SO 4 (aq) + H 2 O(l)

3. Acid reaction with metal carbonates or hydrogen carbonates acids react to give CO 2 (g) when a metal carbonate or metal hydrogen carbonate is added in general – (metal)CO 3 + acid  salt + water + carbon dioxide CaCO 3 (s) + 2HCl(aq)  CaCl 2 (aq) + H 2 O(l) + CO 2 (g) – (metal)HCO 3 + acid  salt + water + carbon dioxide NaHCO 3 (s) + HCl  NaCl(aq) + H 2 O(l) + CO 2 (g)

4. Acid Reaction with metal oxides acids react to give salt and water when a metal oxide is added: in general: – metal oxide + acid  “salt” + water CuO(s) + H 2 SO 4 (aq)  CuSO 4 (aq) + H 2 O(l) CuO(s) + 2HNO 3 (aq)  Cu(NO 3 ) 2 (aq) + H 2 O CuO(s) + 2HCl(aq)  CuCl 2 (aq) + H 2 O(l) CuO(s) + 2CH 3 COOH(aq)  Cu(CH 3 COO) 2 (aq) + H 2 O(l)

5. Acid reactions with bases (even ones without an OH) a base is a substance that reacts with an acid to form water and a salt only, this is known as neutralization – most have an OH, however some do not in general: – base + acid  salt + water NaOH(aq) + HNO 3 (aq)  NaNO 3 (aq) + H 2 O(l) NH 3 (aq) + HNO 3 (aq)  NH 4 NO 3 (aq) (water is “assumed”) NH 3 (aq) + H + (aq)  NH 4 + (aq) (water is “assumed”) H 3 PO 4 (aq) + 3NaHCO 3 (s)  Na 3 PO 4 (aq) + 3H 2 O(l) + 3CO 2 (g) CaCO 3 (s) + 2HCl(aq)  CaCl 2 (aq) + H 2 O(l) + CO 2 (g)

ACIDS Salt + Water Salt + Water + CO2 Salt + H2 Salt + Water (NH4)Salt Water METAL (if more reactive than hydrogen) METAL CARBONATE or HYDROGEN CARBONATE (base) METAL HYDROXIDE (base) BASES (without OH) METAL OXIDE (base)

Acids and bases effects on indicators indicators – substances that change color in an acid or base (concentration of hydrogen ions changes)

Color changes for different indicators are on page 22 of the IB Data booklet