Acids – Compounds which give hydrogen ion in water solution. For eg, HCl Bases – Compounds which give hydroxide ion in water solution. For eg, NaOH

Strong and Weak– Strong acids ionize fully in water to produce large number of H+ ions. For eg, HCl Weak acids ionize partially in water to produce small number of H+ ions. For eg, H3PO4

Strong and Weak– Strong bases ionize fully in H2O to produce large number of OH– ions. For eg, KOH Weak bases ionize partially in H2O to produce small number of OH– ions. For eg, NH4OH

Concentrated Solution– large amount of solute is dissolved in less amount of water. Dilute Solution– small amount of solute is dissolved in a large amount of water.

Diluting Acids and Bases– If concentrated acid (or base) is mixed with water, concentration of H3O+ decreases. Always add concentrated acid/base to water; not water to concentrated acid/base.

Acids– The word ‘Acid’ came from the Latin word ‘Acidus or Acere’ which means sour. Sour in taste such as curd, grapes, etc.

Types of Acids on the basis of their occurrence– Natural Acid– Acids which are obtained from natural sources (plants and animals). Mineral Acids– Acids that prepare from minerals such as HCl.

Note: Organic acids are always weak but mineral acids can be strong as well as weak. We can take dilute weak acids in our body. But strong acids are very harmful for us.

Bases– Bitter in taste and feels soapy on touch. Turns red litmus paper to blue. Substances which contain bases such as soap, detergents, etc.

Conduction of Electricity in Acids/Bases– H+ ions react with water and make H3O+ ions. These H3O+ ions can move in solution to conduct electricity. Acid and base solutions are called electrolytes.

Neutralization Reaction In the reaction between acid and base both neutralize each other and respective salt and water are formed.  Eg: HCl+NaOH→NaCl+H2O Note: H+ and OH– ions combine to form H2O.