Acids and Bases C12

Here is notes on the theory, neutralisation, and conjugate pairing of acids.

Arrehenius Theory requires the presence of water:

Arrehenius definition of an acid : An acid is a substance that dissociates in water to produce H+ ions.

Strong acids are those that fully dissociate in water i.e almost every molecule breaks up to give a H+ ion. Obviously weak acids are the opposite

Mono basic acids are ones that only donate one ion in solution. Di basic and Tri basic give two and three respectively.

HA(acid) + H20 –> H30+ + A- because H+(proton) + H20 –> H30+

the H3O ion is called the Hydronium ion.The bond here is dative covalent.

Arrehenius definiton of base: a substance that dissociates in water to produce OH- ions

Problems with his theory:

he suggested that H+ ions existed on their own, They dont, rather Hydronium ions do.

his definition is restricted to aqueous solutions. Toluene, benzene are not included in the definiton.

not all acid base reactions require water. In his theory the following wouldnt be referred to as acid base reaction even though it is:

NH3 + HCL –> NH4CL

Bronsted lowry theory of acid states that an acid is a proton donor and a base is a proton acceptor. A proton is the same as a H+ ion.

In reactions, whatever gives the proton is the acid and whatever accepts the acid is a base. This theory does not depend on the presence of water. Some substances are amphoteric or amphiprotic which means that they give and accept protons in reactions and hence can act as both acid and base e.g. water

Since reactions under the bronsted lowry theory can occur both ways a system of conjugate acids and conjugate bases is set up. When an acid donates a SINGLE proton is becomes its conugate base and vice verca. A conjugate acid base pair is thus any pair consisting of an acid and a base which differ in only one proton.

Neutralisation is the reaction betweem acid and a base to form salt and water.

The hydrogen ions in the acid react with the hydroxide ions in the base to form the water, the salt is formed from the spectator ions(the others).

Neutralisation in our lives:

Medicine: Stomach acid can build up to painful levels. The excess acid damages the lining of the stomach.For this an antacid is taken which is a base that neutralises the excess acid in our stomachs. AlkaSeltzer, Bisodol, Milk of Magenia contain sodium hydroxide and maggensium hydroxide respectively which are bases

Agriculture: Some plants grow best in basic conditions. Lime is added (calcum oxide) which reacts with water to form slated lime (calcium hydroxide). This neutralises the acidity in the land and makes it suitable for beetroot etc.

Miscellaneous: In shampoo a conditioner is used afterwards to neutralise the acidity of the shampoo which causes the hair scales to open. Wasp stings are alkaline(base dissolved in water) and so acid is used to treat it. Bee stings are the opposite.

Environment: Lime is used in factory chimneys and in lakes to neutralise the acidity that come from gases released by burning or acid rain.

Acids and Bases: By Axle(Ahmad Asad)

2 thoughts on “Acids and Bases C12”

  1. It is nice to see you posting on this topic, I need to book mark this website. Keep up the good work.

Leave a Reply