Chemistry Selina Chapter Answers

Hydrochloric Acid


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HCl gas if formed by comining Hydrogen with chlorine in dilute sunlight. It is explosive in direct sunlight and negligible at dark. In it’s laboratory prepration NaCl is treated with Sulphuric Acid to give out HCl gas which is dried by dehydrating agent i.e. Sulphuric Acid. Other acidsagents like Phosphorus pentaoxide and CaO are not used as they react with HCl. NaCl is preferred as it is cheap.

    When hydrocholric gas is dissolved in water it is called Hyrdrochloric acid. HCl gas is highly soluble in water. It gets ionised in water but not in toulene which shows absense of H30+ ions in toulene. It also tells that HCl is covalent compound. HCl acid is prepared by absorbing HCl gas in water using funnel which provide large surface and prevent back suction.

     It is used for pickeling of metals, removing rust from iron sheets , medicines and extraction of glue from bones. It is also used in manufacture of Aqua Regia (Royal Water) which can even corrode gold and platinum.

     Tests – It forms white fumes of Ammonium Chloride when treated with Ammonia. It also gives white ppt. when treated with Silver Nitrate. It realese chlorine when reacted with oxidising agents like MnO2