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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) (aq)

The H+ ion is present in

acids

The hydroxide, OH- ion, makes solutions

alkaline.

The particular salt made depends on :

the acid used the 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 + WATERSODIUM HYDROXIDE + HYDROCHLORIC ACID

……………...…………… + ……………..SODIUM CHLORIDE WATER

Na Cl + H2O

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+ OH -H+ OH -H+OH -H+ OH -H+ OH -H+ OH -H2O

Na OH + H Cl Na Cl + H2O

H

H+(aq) + OH-(aq) H2O(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 + HNO3 KNO3 + H2O balanced

sodium hydroxide + sulphuric acid = sodium sulphate + water

NaOH + H2SO4 Na2SO4 + H2O

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) + waternote : 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.

againagainagainKeep 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 nitrate water

copper chlorideCopper oxide + hydrochloric acid =

+ water

Copper oxide + sulphuric acid = + copper sulphate water

PbO + HNO3 Pb(NO3)2 + H2O

CuO + HCl CuCl2 + H2O

CuO + H2SO4 CuSO4 + H2O

NOT balanced

2

2 balanced

NOT balanced balanced

balanced