Acids and Bases

idk what this is (its not really notes) §

MgSO4 - salt KMnO4 - salt CH3COOH - acid Cu(OH)2 - base HNO3 - acid LiOH - base

base: Arrhenius: salt: salt is a substance formed when hydrogen from acid is substituted by metal ion.

Arrhenius Model §

• 109. Use the Arrhenius model to define and describe acids and bases in aqueous solution.

Capabilities of Arrhenius Model §

Arrhenius (Swedish Chemist) described a theory of acid-base behaviour centred on the ability of certain substances that contain H or OH to produce hydrogen ions, $H^{+}$ (aq) or hydroxide ions, $O{H}^{-}$ (aq) when dissolved in water. His theory states that:

• an acid is a substance that will ionise in solution producing $H^{+}$ (aq) ions
  • eg $HN{O}_3(aq)\to H^{+}(aq)+N{O}_3^{-}(aq)\dots \dots$
• a base is a substance that will dissociate in solution producing $O{H}^{-}$ (aq) ions
  • eg $NaOH(s)\to O{H}^{-}(aq)+N{a}^{+}(aq)\dots \dots$
• the theory gives a good account of the acid-base behaviour of many acids and ionic hydroxides.

Weaknesses of Arrhenius Model §

• to able to explain or predict the acid-base behaviour of many other compounds:
  • for example, why salts like sodium carbonate and potassium phosphate (which do not contain OH) are basic in nature and not neutral.
  • the Brønsted–Lowry model is more comprehensive and gives a broader and more satisfactory account of acid-base behaviour

Comparing 0.1 mol/L HCl and 1.0 mol/L CH3COOH §

• CH3COOH has a larger concentration
• HCl is a stronger acid because it disassociates fully
• HCl has more electrolytes so it is more conductive than CH3COOH

Reactions of Acids §

• metal (s) + acid (aq) -> salt (check w/ solubility table) + hydrogen gas (g)
• metal oxide (s) + acid (aq) -> salt (check w/ solubility table) + water (l)
• metal hydroxide (check) + acid (aq) -> salt (check) + water (l)
• metal carbonate (check) + acid (aq) -> salt (check) + water (l) + carbon dioxie (g)
• metal hydrogen carbonate (check/trust observation/read q) + acid (aq) -> salt (check) + water (l) + carbon dioxide (g)
  • Ca(HCO3)2 (aq) +2HCl (aq) -> CaCl2 (aq) + 2H2O (l) + 2CO2 (g)

Ionic Reactions §

• in most areas of chemistry, we write ionic reactions, not molecular reactions (even if it is not asked, we assume it wants balanced ionic reactions with state symbols)
• for acids and bases, write and determine what type of acid and bases you are dealing with.
  • eg $NaOH(aq)+HCl(aq)\to NaCl(aq)+H_{2}O(l)$
  • strong base + strong acid (this step is important, explained why later)
  • $N{a}^{+}(aq)+O{H}^{-}(aq)+H^{+}(aq)+C{l}^{-}(aq)\to N{a}^{+}(aq)+C{l}^{-}(aq)+H_{2}O(l)$
  • remove spectator ions:
  • $O{H}^{-}(aq)+H^{+}(aq)\to H_{2}O(l)$
  • if it is a weak acid, then in solution it is present as the same thing.
    • eg CH3COOH -> CH3COOH because it is a weak acid (from molecular to ionic)