Cambridge IGCS Chemistry Coursebook 2023 Chapter 10 知识点整理

这是一篇关于Acids and bases的思维导图，主要内容包括：Characteristic reactions of acids，The nature of acids and bases。

Acids and bases

• Characteristic reactions of acids
  • Reactions of acids
    • • a reactive metal (e.g. magnesium or zinc) • a base (or alkali) - a neutralisation reaction • a metal carbonate or hydrogen carbonate)
    • Reaction of acids with metals
      • metal + acid → salt + hydrogen
    • Reaction of acids with bases and alkalis
      • acid + base → salt + water
    • Reaction of acids with carbonates
      • acid + metal carbonate → salt + water + carbon dioxide
  • Strong and weak acids and alkalis
    • Strong and weak acids
      • dissociation: the separation of a covalent molecule into ions when dissolved in water
      • strong acid: an acid that is completely ionised when dissolved in water - this produces the highest possible concentration of H+(aq) ions in solution, e.g. hydrochloric acid
      • weak acid: an acid that is only partially dissociated into ions in water - usually this produces a low concentration of H+(aq) in the solution, e.g. ethanoic acid
    • What happens to the ions in neutralisation?
      • H+(aq) + OH-(aq) → H2O(l)
    • • an acid is a proton donor (it gives a proton, H+ ion, to a base) • a base is a proton acceptor (it accepts a proton, H+ ion, from an acid)
• The nature of acids and bases
  • Acid
    • Acid: a substance that dissolves in water, producing H-(aq) ions - a solution of an acid turns litmus red and has a pH below 7. Acids act as proton donors.
    • corrosive: a corrosive substance (e.g. an acid) is one that can dissolve or 'eat away' at other materials (e.g. wood, metals or human skin)
    • Organic acids
      • ethanoic acid: CH3COOH——weak——in vinegar
      • methanoic acid: HCOOH——weak——in ant and nettle stings; used in kettle descaler
      • actic acid: CH3CH(OH)CO2H——weak——in sour milk
      • citric acid: G6H8O7——weak——in lemons, oranges and other citrus fruits
    • Mineral acids
      • carbonic acid: H2CO3——strong——in fizzy soft drinks
      • hydrochloric acid: HCL——strong——used in cleaning metal surfaces; found as the dilute acid in the stomach
      • nitric acid: HNO3——strong——used in making fertilisers and explosives
      • sulfuric acid: H2SO4——strong——in car batteries; used in making fertilisers, paints and detergents
      • phosphoric acid: H3PO4——strong——in anti-rust paint; used in making fertilisers
    • Indicators
      • indicator: a substance that changes colour when added to acidic or alkaline solutions, e.g. litmus or phenolphthalein
      • litmus: the most common indicator; turns red in acid and blue in alkali
      • thymolphthalein: an acid-base indicator that is colourless in acidic solutions and blue in alkaline solutions
      • methyl orange: an acid-base indicator that is red in acidic and yellow in alkaline solutions
      • base: a substance that neutralises an acid, producing a salt and water as the only products. Bases act as proton acceptors
      • alkalis: soluble bases that produce OH (aq) ions in water - a solution of an alkali turns litmus blue and has a pH above 7
      • universal indicator: a mixture of indicators that has different colours in solutions of different pH
    • The pH scale
      • pH scale: a scale running from below 0 to 14, used for expressing the acidity or alkalinity of a solution; a neutral solution has a pH of 7
      • • acids have a pH less than 7 • the more acidic a solution, the lower the pH • neutral substances, such as pure water, have a pH of 7 • alkalis have a pH greater than 7.
      • • As we move down from pH 7, the solution is getting more acidic. • Moving up from pH 7, the solution is getting more alkaline.
  • Acid and alkali solutions: the importance of hydrogen and hydroxide ions
    • • the hydrogen ions (H*) in acid solutions turn litmus red • the hydroxide ions (OH*) in alkali solutions turn litmus blue.
    • Acids
      • hydrochloric acid: H+(aq) and Cl- (aq)
      • nitric acid: H+(aq) and NO3- (aq)
      • sulfuric acid: H+(aq), HSO4- (aq) and SO4 2- (aq)
    • Alkalis
      • calistic hydroxide (caustic soda): Na+ (aq) and OH- (aq)
      • potassium hydroxide (caustic potash): K+(aq) and OH- (aq)
      • calcium hydroxide (limewater): Ca 2+(aq) and OH- (aq)
      • ammonia solution (ammonium hydroxide): NH4+ (aq) and OH- (aq)
  • Alkalis and bases
    • What types of substance are alkalis and bases?
      • neutralisation: a chemical reaction between an acid and a base to produce a salt and water only; summarised by the ionic equation H+(aq) + OH (aq) → H2O(l)
      • antacids: compounds used medically to treat indigestion by neutralising excess stomach acid
      • NH4NO3(s) + NaOH(aq) → NaNO3(aq) + H2O(l) + NH3(g)
      • 2NH4NO3(s) + CaO(s) → Ca(NO3)2(s) + H2O(l) + 2NH3(g)
      • Alkalis
        • sodium hydroxide (caustic soda): NaOH)——strong——in oven cleaners (degreasing agent); in making soap and paper; other industrial uses
        • potassium hydroxide (caustic potash): КОН——strong——in making soft soaps and biodiesel
        • calcium hydroxide (limewater): Ca(OH)2——strong——to neutralise soil acidity and acidic gases produced by power stations; has limited solubility
        • ammonia solution (ammonium hydroxide): NH3 (aq) or NH4OH——strong——in cleaning fluids in the home (degreasing agent); in making fertilisers
      • Bases
        • calcium oxide: CaO——for neutralising soil acidity and industrial waste; in making cement and concrete
        • magnesium oxide: MgO——in antacid indigestion tablets
  • Metal oxides and non-metal oxides
    • Acidic and basic oxides
      • acidic oxides: oxides of non-metals that will react with bases and dissolve in water to produce acid solutions
      • basic oxide: oxide of a metal that will react with acids to neutralise the acid
      • Non-metals
        • sulfur——burns with bright blue flame——colourless gas (sulfur dioxide SO2)——dissolves, turn litmus red
        • phosphorus——burns with yellow flame——white solid (phosphorus(V) oxide, P2O5)——dissolves, turns litmus red
        • carbon——glows red——colourless gas (carbon dioxide, CO2)——dissolves slightly, slowly turns litmus red
      • Metals
        • sodium——burns with yellow flame——white solid (sodium oxide, Na2O)——dissolves, turn litmus blue
        • magnesium——burns with bright white flame——white solid (magnesium oxide, MgO)——dissolves sligntly, turns litmus blue
        • calcium——burns with red flame——white solid (calcium oxide, CaO)——dissolves, turn litmus blue
        • iron——burn with yellow sparks——blue-black solid (iron oxide, FeO)——insoluble
        • copper——does not burn, turns black——black solid (copper oxide, CuO)——insoluble
    • Neutral and amphoteric oxides
      • amphoteric compound: a compound (hydroxide or metal oxide) that reacts with both an acid and an alkali to give a salt and water
      • ZnO(s) + 2HCl(aq) → ZnCl2(aq) + H2O(l)
      • ZnO(s) + 2NaOH(aq) → Na2ZnO2(aq) + H2O(l)
      • Al2O3(s) + 2NaOH(aq) → 2NaAlO2(aq) + H2O(l)