Ethanol is added to chloroform to inhibit its oxidation to phosgene (COCl₂) – a negative catalyst. Others are positive catalysts that speed up reactions.
Explanation:
Smelting involves heating a metal oxide ore (roasted or calcined) with a reducing agent like coke (carbon) or CO to obtain the metal in the molten state. Example: Fe₂O₃ + 3CO → 2Fe + 3CO₂ in blast furnace. Calcination: heating carbonate/ hydroxide ore in absence of air. Roasting: heating sulfide ore in excess air. Leaching: chemical dissolution of ore. Smelting is a key pyrometallurgical step.
Explanation:
Atomic number 8 is oxygen (2,6). It needs 2 more electrons to complete octet, so it gains 2 or shares 2 electrons. Its valency is 2 (typically). It can form two covalent bonds. In H₂O, oxygen forms two bonds.
Explanation:
CaOCl₂ + 2HCl (dil.) → CaCl₂ + Cl₂ + H₂O. It also releases Cl₂ on reaction with CO₂ in air: CaOCl₂ + CO₂ → CaCO₃ + Cl₂. Water alone hydrolyses it slowly. NaOH does not release Cl₂. The chlorine gas is responsible for bleaching and disinfection.
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