Say we start with a strong alkali containing Universal indicator, and gradually add acid The alkali will gradually get weaker and weaker as it is cancelled out by the acid. Eventually, with the right amounts, the solution becomes neutral. The neutral compounds produced by neutralisation are called SALTS ACID + ALKALINE  NEUTRAL SALT + WATER ALKALINE HYDROXIDE (aq) The H + ion is present in acids The hydroxide, OH - ion, makes solutions alkaline. The particular salt made depends on : the acid usedthe metal in the alkali neutralising nitric acid produces salts called NITRATES neutralising sulphuric acid produces salts called SULPHATES neutralising hydrochloric acid produces CHLORIDES.

NEUTRALISATION EQUATIONS. ACID + ALKALI = SALT + WATER SODIUM HYDROXIDE + HYDROCHLORIC ACID  ……………...…………… + …………….. SODIUM CHLORIDEWATER Na Cl + H 2 O POTASSIUM HYDROXIDE + SULPHURIC ACID  ……………...………...…… + …………….. POTASSIUM SULPHATE WATER CALCIUM HYDROXIDE + NITRIC ACID  …………………………. + …………….. CALCIUM NITRATE WATER AMMONIA (aq) + HYDROCHLORIC ACID  ………………………………… + …………….. AMMONIUM CHLORIDE WATER Na OH + H Cl 

NEUTRALISATION EQUATIONS. Acids contain H + Alkalis contain OH - Let’s mix H + and OH - in the correct amounts : H+H+ OH - H+H+ H+H+ H+H+ H+H+ H+H+ H2OH2O Na OH + H Cl  Na Cl + H 2 O H H + (aq) + OH - (aq)  H 2 O(l) This is an ionic equation showing exactly what happens during neutralisation Once the H + and the OH - have reacted, the salt is a combination of : the alkali metal ion that was in the hydroxide the negative ion with the H + in the acid.

WRITING BALANCED EQUATIONS FOR NEUTRALISATION. potassium hydroxide + nitric acid = potassium nitrate + water KOH + HNO 3  KNO 3 +H2OH2O balanced sodium hydroxide + sulphuric acid = sodium sulphate + water NaOH + H 2 SO 4  Na 2 SO 4 +H2OH2O NOT balanced balanced 2 2

HOW DO WE MAKE SALTS OF TRANSITION METALS ? We can react their oxides and hydroxides with acid. Transition metal oxides and hydroxides though, do not dissolve in water. They are called BASES. Base + acid  salt + water But because bases are insoluble, the method used is different. Our example will be : Copper oxide(s) + sulphuric acid(aq)  copper sulphate(aq) + water note : solid

Making copper sulphate, starting with copper oxide and sulphuric acid. warm sulphuric acid(aq) add copper oxide (black powder) all the copper oxide reacts and some of the acid changes to copper sulphate (blue). again more acid reacts, more copper sulphate made. again Keep adding copper oxide to the acid, with stirring until no more will react. Solution goes bluer as more copper sulphate is made. All the acid gets used up the excess copper oxide can be filtered off the copper sulphate solution coming through the filter is pure.

Base + acid = salt + water An insoluble oxide of a transition metal Lead oxide + nitric acid = + lead nitratewater copper chloride Copper oxide + hydrochloric acid = + water Copper oxide + sulphuric acid = + copper sulphate water PbO + HNO 3  Pb(NO 3 ) 2 +H2OH2O CuO + HCl  CuCl 2 +H2OH2O CuO + H 2 SO 4  CuSO 4 +H2OH2O NOT balanced 2 2 balanced NOT balanced balanced balanced