Uses of HCl acid.

Here are the uses of $\text{HCl}$ acid as listed in your notes:

• Removing rust from metal: For example, de-scaling iron before it is galvanized or electroplated.
• Treatment of water: Used in chlorination at water works.
• Sewage treatment.
• Making dyes, drugs, and photographic materials: Such as silver chloride on photographic films.
• pH control and neutralization: In industries that require purity.

Your notes also mention "Environmental Pollution by chlorine & its compounds", stating that:

• Chlorine is a non-metallic element belonging to the family of halogens.
• Chlorine water contains hydrochloric acid and chloric(I) acid.
• Hydrochloric acid reacts with metals above hydrogen in the reactivity series, liberating hydrogen gas.

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