[Science Form 2] Neutralisation

The process in which an acid reacts with an alkali to form a neutral solution containing a salt and water is called neutralisation.

As an acid is added to an alkali, the pH of the solution decrease. The end point of neutralisation is when pH value of the solution is 7. When this happens, it means that the alkali has been neutralised.

The balance of acids and alkalis is crucial for our good health and for our environment. If one dominates too much over the other, all sorts of things can go wrong and life on earth would be in peril.

Acid rain, fish deaths from acid rain, dirty swimming pools, Legionnaire bacteria outbreaks and indigestion are examples of acids and alkalis being out of balance.

The following are the examples of the application of neutralisation in our daily life:

1. Shampoos are usually slightly alkaline. They neutralise the acidic oil that the skin secretes to keep our hair healthy and strong.
   
   
2. Hair conditioner, which is slightly acidic, neutralises the residue of shampoo on the hair and makes the hair smooth and shiny.
   
   
3. Bee stings are acidic. They can be treated with bicarbonate powder, which is a weak alkali.
   
   
4. Toothpastes are alkaline. They neutralise the acid produced by bacteria that act on the food in our mouth.
   
   
5. Plants grow well in soil that is neutral. Farmers add slaked lime to reduce the acidity in the soil.

Facts:

• The plant hydrangeas only produces pink or white flowers in an alkaline soil, and blue flowers in an acidic soil.
  
  
• In order to digest food and kill the kinds of bacteria and viruses that come with the food, the inside of our stomach is acidic. As we drink more alkaline water; more hydrochloric acid is secreted to maintain the acidic pH value in our stomach.