NEUTRALISATION

==Neutralisation== Neutralisation is a type of chemical reaction involving an '''acid''' and a '''base'''. [image:http://i.imgur.com/3LXNopW.gif?1] Adding an acid to a base reduces the alkalinity of the solution. Adding a base to an acid reduces the acidity of the solution. In both cases this brings the pH closer to 7 (neutral) If the right amount of acid / base is added the solution will be neutral (pH 7). An indicator can be used to show when the solution is neutral (e.g. universal indicator will turn green). If excess acid is added the solution will become more acidic. If excess base is added the solution will become more basic. ===What's going on=== Acids release H^+^ ions in solution and this is what makes the solution acidic. Most bases (alkalis) will release OH^-^ ions into solution and this is what makes the solution more basic. H^+^ and OH^-^ ions will readily combine to form water which is neutral. Neutralisation: H^+^ + OH^-^ → H~2~O The equation above only accounts for the H^+^ and OH^-^ that are released by an acid / alkali. A base usually contains a metal ion and an acid always contains a non-metal ion. These metal & non-metal ions combine to forma salt. This means that an Acid-Base (neutralisation) reaction can be summarised as follows: Acid + Base → Salt + Water Note that both of the products formed (salt and water) are neutral. This is why the reaction is called a neutralisation reaction. The name of the salt produced in a neutralisation reaction can be derived from the acid and base used. A base usually contains a metal and this forms the first part of the salts name. The acid will contain a non-metal ion that determines the second half of the name. *'''Hydrochloric acid''' always forms '''metal-chloride''' salts *'''Sulphuric acid''' always forms '''metal-sulphate''' salts *'''Nitric acid''' always forms '''metal-nitrate''' salts For instance in a reaction between Sulphuric Acid and Sodium Hydroxide (base)... Sulphuric acid + Sodium Hydroxide → Sodium Sulphate (salt) + Water ==Isolating a salt from solution== [image:http://i.imgur.com/H9Kixjz.gif] In order to separate the salt from water the solution can be heated in an evaporating basin. The water will evaporate leaving behind solid salt crystals.