2 The pH scale Hydrogen Ions make acidic solutions Hydroxide ions make basic/alkaline solutions.Bases are substances that can neutralise acids. They are usually metal oxides or metal hydroxides.Alkalis are soluble basesAlkalineNeutralAcid
3 Neutralisation H+ (aq) + OH-(aq) -> H2O (l) The acid reacts with the alkali to form a salt and water which is a neutral solution. The hydrogen ions in the acid join with the hydroxide ions in the alkali to form a neutral water molecule. The gas in the acid reacts with the metal or ammonium in the alkali to form an ionic salt.E.g.Hydrochloric acid + sodium hydroxide -> sodium chloride +waterHCl(aq) NaOH(aq) > NaCl(aq) H20 (l)
4 Reactions of Salts Acid + Metal -> a salt + hydrogen E.g. Sulphuric acid + potassium -> potassium sulphate + hydrogenThis is a displacement reactionAcid + Base -> a salt + waterE.g. Sulphuric acid + sodium oxide -> sodium sulphate + waterThis is a Neutralisation reactionAcid + Alkali -> a salt + waterE.g. Sulphuric acid + potassium hydroxide -> potassium sulphate + waterThis is a neutralisation reactionAcid + Carbonate -> a salt + water + carbon dioxideE.g. Sulphuric acid + copper carbonate -> copper sulphate + water + carbon dioxide
5 This comes from the acid Naming Saltstype of metal or ammonium in the base/alkali/metal/carbonate which reacts with the acidThis comes from the acidSodium ChlorideRememberHydrochloric acid makes chloride saltsSulphuric acid makes sulphatesNitric acid makes nitrates
6 Precipitation Reactions This is a reaction where a solid insoluble salt is produced when two soluble salt solutions are mixed together. This type of reaction is important when we want to remove heavy metal ions from polluted water.E.g. Lead nitrate + Sodium chloride -> lead chloride + sodium nitratePb(NO3)2(aq) NaCl(aq) > PbCl2(s) NaNO3(aq)E.g.Silver nitrate + potassium iodide -> silver iodide + potassium nitrateAgNO3(aq) KI2(aq) > AgI(s) KNO3(aq)
7 QuestionsName the salt which is produced when hydrochloric acid reacts with ammonium hydroxide.Which ions make acidic solutions?What is an alkali?Write the balanced symbol equation for sulphuric acid + potassium. Include the state symbolsWhat is produced in a precipitation reaction?What is the equation for a neutralisation reaction?