### Theory:

 S.No. Properties Acid Base 1. Taste Sour taste Bitter taste 2. Litmus test Blue litmus turns red. Red litmus turns blue. 3. Electrical conductivity Since their aqueous solutions contain ions, they conduct electricity. Conducts electricity just as acids can. 4. Reaction with metals Produces hydrogen gas when they react with active metals. $\begin{array}{l}\mathit{Mg}+{H}_{2}{\mathit{SO}}_{4}\phantom{\rule{0.147em}{0ex}}\stackrel{}{⟶}\phantom{\rule{0.294em}{0ex}}\mathit{Mg}{\mathit{SO}}_{4}+{H}_{2}↑\\ \\ \mathit{Zn}+\mathit{HCl}\phantom{\rule{0.147em}{0ex}}\stackrel{}{⟶}\phantom{\rule{0.147em}{0ex}}{\mathit{ZnCl}}_{2}+\phantom{\rule{0.147em}{0ex}}{H}_{2}↑\end{array}$ Produces hydrogen gas and salt when they react with metals. $\mathit{Zn}+{\mathit{2NaOH}}_{2}\phantom{\rule{0.147em}{0ex}}\stackrel{}{⟶}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}{\mathit{Na}}_{2}\mathit{Zn}{O}_{2}+{H}_{2}↑$ 5. Reaction with metallic oxide Salt and water are produced. $\mathit{CaO}+{H}_{2}{\mathit{SO}}_{4}\stackrel{}{⟶}\phantom{\rule{0.147em}{0ex}}{\mathit{CaSO}}_{4}+\phantom{\rule{0.147em}{0ex}}{H}_{2}O$ Reacts with non-metallic oxides to produce salt and water. $\mathit{CaO}+{H}_{2}{\mathit{SO}}_{4}\stackrel{}{⟶}\phantom{\rule{0.147em}{0ex}}{\mathit{CaSO}}_{4}+\phantom{\rule{0.147em}{0ex}}{H}_{2}O$ 6. Reaction with acid/base Acids and bases combine to form salt and water. ${\mathit{Ca}\left(\mathit{OH}\right)}_{2}+{\mathit{CO}}_{2}\phantom{\rule{0.147em}{0ex}}\stackrel{}{⟶}\phantom{\rule{0.147em}{0ex}}{\mathit{CaCO}}_{3}+{H}_{2}O$ Acids and bases combine to form salt and water. ${\mathit{Ca}\left(\mathit{OH}\right)}_{2}+{\mathit{CO}}_{2}\phantom{\rule{0.147em}{0ex}}\stackrel{}{⟶}\phantom{\rule{0.147em}{0ex}}{\mathit{CaCO}}_{3}+{H}_{2}O$ 7. pH < $$7$$ > $$7$$ 8. In aqueous solutions Produces $$H^+$$ ions. Produces $$OH^-$$ ions.

Uses of acids:
• Since it is used to make many other compounds, sulphuric acid is known as the "King of Chemicals." It is also used in car batteries.
• In toilets, hydrochloric acid is used as a cleaning agent.
• Citric acid is used to make effervescent salts and is also used as a food preservative.
• Fertilisers, dyes, colours and medicines are all made with nitric acid.
• Iron and manganese deposits on quartz crystals are removed with oxalic acid. It is also used to remove black stains and as wood bleach.
• In aerated beverages, carbonic acid is used.
• Baking powder has tartaric acid as a component.
• Our stomachs generate hydrochloric acid, which helps in the digestion of food.
• Vinegar contains acetic acid, which is used to preserve food.
• Benzoic acid is also used in the preservation of foods such as pickles.
• Important laboratory reagents include hydrochloric acid, nitric acid and sulphuric acid.
• Nucleic acids are the essential nuclear substance found in all living creatures' cells. Deoxyribonucleic acid (DNA) is found in animals, whereas ribonucleic acid (RNA) is found in plants.
• Pickles remain in good condition for long time due to the presence of vinegar (acetic acid) or benzoic acid.
Uses of bases:
• In the production of soap, sodium hydroxide is used.
• Buildings are whitewashed with calcium hydroxide.
• Bathing soaps are made with potassium hydroxide.
• Sodium hydroxide is used to make washing soaps, also used in paper industries, textile industries and medicines.
• Aluminum hydroxide and magnesium hydroxide are used in antacids to cure acidity problems.
• Ammonium hydroxide is used to manufacture fertilisers, nylon, plastics and
rubber.
• Grease stains on clothing are removed with ammonium hydroxide.
Do you know?

Tin metal (eyam) is used to coat copper or brass cooking vessels because the organic acids present in the food materials will react with copper and make the food poisonous. The tin protects the vessel from acids, preventing food poisoning.