Acids, Bases and Salts

Acids:

• Acids are those  substances which gives H+ inside a solution.
• Ph 1 to Ph 3 are considered as Strong Acids.
• Ph 4 to Ph 6 are considered as weak acids.
• Acidic substances like lemon juice , vinegar etc.. tastes sour.
• Hydrochloric acids, nitric acids are some  examples of  strong acids.
• Acetic acids, phosphoric acids are some examples of weak acids.

Bases:

• Bases are those substances which give hydroxide ions( OH-) inside a solution.
• Ph 8 to Ph 14 are considered as bases.
• Ph 8 to 10 are weak bases.
• Ph 11 to 14 are strong bases.
• Bases tastes bitter and are are soapy in nature.
• Sodium hydroxide , calcium hydroxide are some examples of strong bases.
• Ammonia, hydrogen sulphide are some examples of weak bases.

Indicators:

• Substances which are used to identify another substance acidic or basic nature are termed as Indicators.
• Indicators change their colour when exposed to a acid or a base.
• Turmeric, China Rose are some examples of Natural Indicators.

Litmus Paper:

• Litmus is the most commonly used natural indicator.
• It is extracted from Lichens.
• It turns red when added to an acidic solution.
• It turns blue when added to a basic solution.
• The solutions which does not change it’s colour are known as neutral solutions.
• Neutral Solutions have a Ph 7.

Acid Rain:

• Biological processes on land lead to the formation of harmful gases.
• Acid rain is caused due to sulphuric acid and nitric acid.
• When normal rain falls, these harmful gases get mixed with the rain water and thus forms acid rain.
• Acid rain is also harmful to the health of humans.
• Acid rain can travel longer distances.
• Acid rain is very harmful for buildings, monuments, forests , aquatic life etc..

Neutralization:

• The reaction which takes place between acids and bases to give salts and water is known as Neutralisation Reaction.
• For example: when hydrochloric acid is mixed with sodium hydroxide it gives sodium chloride (salt) and water.
• Hydrochloric acid is present on our stomach and it helps in the digestion of our food..
• If we suffer from indigestion then we take antacids such as milk which contain magnesium hydroxide that neutralises the effect of excessive acid.
• Acids of ant bites can be neutralised by rubbing moist baking soda.
• Excessive acids in soil is treated with bases like quick lime or slaked lime.