DEFINE ALKALI? | THE PROPERTIES & USES OF ALKALI IN WET PROCESSING OF TEXTILE?

ALKALI:

The compounds which contain oxide (O2-) or hydroxide ion, react with acids & produce salt & water are known as alkali. Alkalis are ionized in water & produce hydroxyl ion (OH -). Example: NaOH, KOH etc.

Properties:

1. Alkalis are too much soluble in water.

2. It is ionized in water & produce hydroxyl ion (OH -). NaOH = Na+ + OH -

3. It changes the color of litmus from red to blue. Red litmas + H+ = blue litmas.

4. It reacts with acid & produce salt & water. HCl + NaOH = NaCl + H2O.

5. The alkaline soln of alkali damage organic substances or life cells.

USES OF ALKALI IN WET PROCESSING OF TEXTILE:

• NaOH is used in scouring & mercerizing of textile wet processing.
• NaOH is used in the production of viscose rayon from cellulose.
• NaOH is used to produce paper, petroleum & in the laboratories as reagent.
• Ca(OH2) is used to produce bleaching powder.
• Ca(OH2) is used to remove the hardness of water.
• NaOH&Ca(OH2) are used in various washing purposes.