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Monday, 6 April 2020

Facts about Acids, Bases and Salts

FACTS ABOUT ACIDS, BASES & SALTS


FACTS ABOUT ACIDS

Acids are substances which produces hydronium ion (H3O+) in its aqueous solution.

An acid is sour in taste.

An acid turns blue litmus paper into red.

Sulphuric acid is also known as 'Oil of Vitriol'.

'King of chemicals' is sulphuric acid.

It is manufactured through 'contact process'.

Pure, concentrated sulphuric acid is a bad conductor of electricity while the dilute acid is a good conductor of electricity.

Sulphuric acid is used in the manufacture of chemicals, dyes and pigments, soaps and detergents, plastics and fibres (rayon).

It is used in the manufacture of fertilizers (super phosphate of lime, ammonium sulphate), explosives (nitroglycerine and trinitro toluene (i.e., TNT). a It is used in petroleum refining, tempering of steel and in lead storage batteries.

Earliest known acid is acetic acid.

Substance and Acid

1. Oranges, Lemon - Citric acid
2. Tamarind, Grapes - Tartaric acid
3. Tea - Tannic acid
4. Vinegar - Acetic acid
5. Urine - Uric acid
6. Ant - Formic acid
7. Milk, Curd - Lactic acid
8. Fat - Stearic acid
9. Olive oil - Oleic acid
10. Apple - Maleic acid, Ascorbic acid

The acid that can be used as a hypnotic is barbituric acid.

Old name of hydrochloric acid is muriatic acid.

The acid that functions as digesting agent in our body is hydrochloric acid.

Dilute phenol is called carbolic acid.

Weakest (inorganic) acid is hydrocyanic acid.

The acid which fumigates when exposed to air is nitric acid.

To purify gold, it should be treated with concentrated nitric acid.

Old name of nitric acid is aquafortis.

Acid and Use

1. Citric acid - Food preservation, Vitamin C preparation
2. Oxalic acid - Ink stain remover
3. Boric acid - Eye-wash/antiseptic
4. Carbonic acid - Flavoured drinks
5. Tartaric acid - Baking powder
6. Acetic acid - Flavouring food, food preservation
7. Hydrochloric acid - Cleaning of metal items, printing industry
8. Benzoic acid - Preservation of fruit pulps and making of perfumes and medicines
9. Nitric acid - Explosives
10. Phosphoric acid - Fertilizers

Gastric juice contains hydrochloric acid Cola contains phosphoric acid.

Ordinary soda water is chemically carbonic acid.

Tartaric acid: Constituent of baking powder (reacts with sodium bicarbonate to release car-bon dioxide which makes the dough light and spongy).

FACTS ABOUT BASES

Oxides and hydroxides of metals (or metal like radicals) are called bases.

Sodium hydroxide: Manufacture of soap.

Calcium hydroxide:

i) Manufacture of bleaching powder, mortar
ii) Softening of hard water,
iii) Neutralizing acid in the soil and in water supplies.

Potassium hydroxide: Alkaline batteries.

Magnesium hydroxide: As an antacid to neutralize acidity caused by hydrochloric acid in the stomach.

Aluminium hydroxide: Foaming agent in fire extinguishers.

Ammonium hydroxide: Used to remove grease stains from clothes.

pH value

The measure of the acidic or basic character of a liquid or solution is the pH value.

The pH scale is introduced by Sorensen.

pH value generally starts from 0 and ends at 14

Pure neutral solutions are having pH exactly 7.

pH value greater than 7 and upto 14 is basic.

pH value 0 to 6.9 is acidic.

Generally human secretions other than blood have pH 6.1 to 6.9.

The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali are called Buffer Solutions.

pH Value

1. Pure water - 7
2. Sea water - 8.5
3. Human blood - 7.3 or 7.4
4. Saliva - 6.5 - 7.4
5. Coffee - 5
6. Tea - 5.5
7. Milk - 6.5
8. Bear - 4.5
9. Acid rain - 3.00 - 4.5
10. Lemon juice - 2.4

FACTS ABOUT SALTS

Salts are ionic compounds containing a positive ion (cation) and a negative ion (anion).

Sodium chloride (NaCI) is a normal salt.

Hydrolysis is a reaction in which a salt reacts with water to form a solution which is either acidic or alkaline.

Salts containing water of crystallisation are called hydrated salts.

Sodium chloride is used as a flavouring agent in food.

Sodium bicarbonate is an essential ingredient in baking powder.

Sodium carbonate as washing soda, manufacturing of glass etc

Sodium benzoate as a food preservative for pickles

Potassium nitrate is used in the production of gun powder.

What is Hygroscopy?

Ans: Hygroscopy is the property of salts to absorb atmospheric moisture at ordinary temperature without dissolving in it. Anhydrous calcium chloride, conc. sulphuric acid, phosphorus pentoxide, calcium oxide (quick lime), silica gel, alcohol are the examples of hygroscopic substances.

Calcium chloride: Dehydrating agent used for removing moisture from gases.

Calcium carbonate (Lime stone): In the construction of building, cement industry.

Characteristics of Acids and Bases

Acid -> Sour taste -> Blue litmus to red -> Give H+ ions in solution
Base -> Bitter taste -> Red litmus to blue -> Give OH- ions in solutions

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