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Acid vs Base:

Acid	Base
Contains H+ /H3O+ ions in aqueous solution	Contains OH– ions in aqueous solution
Turns blue litmus paper red.	Turns red litmus paper blue.
Sour in taste.	Bitter in taste.
Neutralizes solution containing OH– ions by producing salt.	Neutralizes solution containing H+ ions by producing salt.
E.g. Sulphuric Acid, Acetic Acid, etc.	E.g. Sodium Hydroxide, Potassium Hydroxide, etc.

• Identification of Acid or base:

Indicator	Acid	Base
Litmus Test	Red litmus: No color change Blue litmus: Turns red	Red litmus: Turns blue Blue litmus: No color change
Phenolphthalein Solution Test	Solution is colorless	Solution turns pink
Methyl Orange Test	Solution turns red	Solution turns yellow
Onion juice	Do Not lose smell	Lose smell
Vanilla	Do Not lose smell	Lose smell

• Chemical properties of Acids and Bases:
• Acids:
1. Reaction with metals: Displaces hydrogen from acid and forms salt.

1. Reaction with Carbonates: Produces Salt, Carbon Dioxide and Water.

1. Reaction with Bicarbonates: Produces Salt, Carbon Dioxide and Water.

1. Reaction with Metal Oxides: Produces salt and water

• Bases:
1. Reaction with non-metallic oxides: Salt is produced.

• Reaction of Acid and Base with each other: (Neutralization reaction) Produces Salt and water

             

• Common properties of acids and bases :
• Electrical Conduction: In aqueous solution, free H+ ions from acid and free OH– ions from base causes  electrical conduction. Glucose and alcohols do not show electrical conduction, due to absence of H+ or OH– ions in aqueous solution  
• Dissolution in water:
1. Acids dissociates to form H+ ions in water.

1. Bases dissociates to form OH– ions in water.

All bases are not soluble in water. Soluble bases are called alkali e.g. NaOH.

• Dilution: It is mixing of acid or base in water, to decrease concentration of H+ or OH– ions.
• Strength of acid or base:
• pH scale: A strip of equally spaced colors, used to measure concentration of H+ ions.
• pH value: Marking from 0-14 on pH scale.
• Acidic Nature:  pH value less than 7.
• Neutral Nature: pH value is 7.
• Basic Nature: pH value greater than 7.

Strength	Concentration	pH value
Strong acids	High H+ ions	Low
Weak acids	Low H+ ions	High
Strong bases	High OH– ions	High
Weak bases	Low OH– ions	Low

 

• pH in everyday life:

 

• Human Health: Change in pH of human body below 7 or  above 7.8 leads to sickness
• Aquatic Life: Acid rains decreases the pH of water resources below 5.4. This leads to suffering of aquatic life.
• Plant Growth: Specific range of pH in soil is required for healthy plant growth.
• Healthy teeth: Degradation of food by bacteria produces acid in mouth. Fall of pH below 5.5 lead to  corrosion and decay of tooth. To prevent this toothpaste used are basic in nature.
• Food digestion: Hydrochloric Acid produced by stomach helps in food digestion. During indigestion, excess of acid is released into stomach causing irritation. Magnesium Hydroxide which is basic in nature neutralises acid and provides relief.  
• Self defence: Bee sting injects acid which causes pain and irritation. Applying baking soda gives relief. Stinging hair of nettle leaves injects methanoic acid into body. Leaves of dock plant contains liquids of basic nature, when these leaves are rubbed in stung area, it gives relief.  

• Naturally occurring acids and their sources:

Source	Acid
Vinegar	Acetic acid
Orange , Lemon, etc	Citric acid
Tamarind	Tartaric acid
Tomato	Oxalic acid
Curd	Lactic acid
Ant sting, Nettle sting	Methanoic acid

• Salt: Salt is a product obtained in Acid-Base Neutralization Reaction which contains a positive and a negative radical.
• Salt Family:
• Sodium Salts: Contains Sodium Radical. E.g. Sodium Chloride (NaCl), Sodium Sulphate (Na2SO4), Sodium Nitrate (NaNO3), etc.
• Salts of Chloride Family: Contains Chlorine Radical. E.g. Sodium Chloride (NaCl), Potassium Chloride (KCl), Ammonium Chloride (NH4Cl), etc.
• Salts of Sulphate Family: Contains Sulphate Radical (SO42-). E.g. Potassium Sulphate (K2SO4 ), Sodium Sulphate (Na2SO4 ), Calcium Sulphate (CaSO4 ), etc.
• pH of Salts:

pH	Reaction	Example
Neutral Salts (pH = 7)	Strong Acid + Strong Base ⟶ Neutral Salt	NaCl, KNO3, NaNO3, etc.
Acidic Salts (pH < 7)	Strong Acid + Weak Base ⟶ Acidic Salt	NH4Cl, ZnSO4, etc.
Basic Salts (pH > 7)	Weak Acid + Strong Base ⟶ Basic Salt	Na2CO3, CH3COONa, etc

• Uses of Common Salt (Sodium Chloride):
1. Used in food material for taste and as a food preservative.
2. Used as raw material for production of various chemical like:  

• Sodium Hydroxide:

• Bleaching powder:

• Uses: For bleaching cotton and linen in the textile industry, wood pulp in paper factory, washing clothes in laundry, as an oxidising agent, as disinfectant for drinking water.

• Sodium Hydrogen Carbonate:

    

• Uses: It is used in making baking powder, used as an antacid in acidity problems, used as fire extinguisher.
• Sodium Carbonate:

• Uses: Used in glass, soap and paper industries, in manufacturing of sodium compounds such as borax, used as cleaning agent for washing clothes, used to remove permanent hardness of water.

• Water of Crystallization: The fixed number of water molecules in each formula unit of a salt is water of crystallization.

• Plaster of Paris: Gypsum heated at 373 K loses water molecule and forms Calcium Sulphate Hemihydrate (CaSO4 ᐧ1/2H2O ) or Plaster of Paris. It is white powder which on mixing with water, regains its hardness, by forming gypsum again.

• Uses:
1. Used by doctors to support fractured bones.
2. Used to make toys, decorative materials and to make surface smooth.