Properties of Acids and Alkalis

6.1

Properties of Acids and Alkalis

Properties of an acid and an alkali

Acid	Alkali
pH value less than 7	pH value more than 7
Tastes sour	Tastes bitter
Corrosive	Corrosive
Turns blue litmus paper red	Turns red litmus paper blue
Reacts with metals to produce hydrogen gas	Does not react with metals

Acidic and Alkaline Substances

- Example : Vinegar - Acidic substances & Soap - Alkaline substances

- Indicator is a colouring or a mixture of different colourings that changes colour based on the substance tested

Indicator

Phenolphthalein

Acid & neutral: Colourless

Alkali: Pink

Universal Indicator

Acid: Red

Neutral: Green

Alkali: Blue

Methyl orange

Acid: Red

Neutral and Alkali: Yellow

Blue litmus paper

Acid: Red

Neutral and Alkali: Blue

Red litmus paper

Acid and neutral: Red

Alkali: Blue

Strength of Acids and Alkalis

- The pH scale is used to show the strength of acids or alkalis

- The lower the pH value, the stronger the acid

- The higher the pH value, the stronger the alkali

Uses of Acids and Alkalis in Daily Life

Acid

Alkali

1) Tartaric acid - Tartaric acid

2) Fizzy drink - Carbonic acid

3) Car battery - Sulphuric acid

4) Pickle - Vinegar

1) Soap - Potassium hydroxide

2) Fertiliser - Ammonia

3)Detergent - Sodium hydroxide

4)Antacid pills - Magnesium hydroxide