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UPPCS Chemistry Gap Sheet: Common Compounds: Names and Formulas.
UPPCS has asked 23 of these. 3 have not been asked yet. Lock the first list, then read the second: it holds what UPPCS has not used yet.
First, the concept
A common name may hide the metal ion, the acid radical or water of crystallisation. Learn the chemical name and formula together. Hydrated salts have fixed water molecules within their crystals.
Carbonate, hydrogen carbonate, hydroxide and sulphate are different families. Heating may remove crystal water without changing the metal. A familiar use does not mean that a compound is safe to eat.
✅ Already asked (23)
Sodium and potassium compounds
- Common salt · Sodium chloride, NaCl.
- Baking soda · Sodium hydrogen carbonate, NaHCO₃.
- Washing soda · Sodium carbonate decahydrate, Na₂CO₃·10H₂O.
- Caustic soda · Sodium hydroxide, NaOH.
- Hypo · Sodium thiosulphate pentahydrate, Na₂S₂O₃·5H₂O; photographic fixer.
- Borax · Sodium tetraborate decahydrate, Na₂B₄O₇·10H₂O.
- Potassium permanganate · KMnO₄; a purple oxidising agent.
Calcium compounds
- Quicklime · Calcium oxide, CaO.
- Slaked lime · Calcium hydroxide, Ca(OH)₂.
- Limestone, chalk and marble · Mainly calcium carbonate, CaCO₃.
- Gypsum · Calcium sulphate dihydrate, CaSO₄·2H₂O.
- Plaster of Paris · Calcium sulphate hemihydrate, CaSO₄·½H₂O.
- Bleaching powder · Common school formula CaOCl₂; commercial material is a mixture of calcium compounds.
- Calcium carbide · CaC₂; produces acetylene on contact with water.
- Bone mineral · Mainly calcium phosphate in the form of hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂.
Other familiar salts and oxides
- Blue vitriol · Copper sulphate pentahydrate, CuSO₄·5H₂O.
- Green vitriol · Ferrous sulphate heptahydrate, FeSO₄·7H₂O.
- Epsom salt · Magnesium sulphate heptahydrate, MgSO₄·7H₂O.
- Potash alum · KAl(SO₄)₂·12H₂O; a double salt.
- Chinese white · Zinc oxide, ZnO; also called philosopher's wool.
- Silica · Silicon dioxide, SiO₂; quartz and the main constituent of ordinary sand.
- Hydrogen peroxide · H₂O₂; an oxidising and bleaching agent.
- Milk of magnesia · Suspension of magnesium hydroxide, Mg(OH)₂; an antacid.
❌ Not asked yet (3)
Items marked 'asked in other exams' have come in UPSC or other state exams, not yet in UPPCS.
🔒 3 items not asked yet
Sodium and potassium compounds: 1 · Other familiar salts and oxides: 2
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⚠️ Washing soda is not baking soda; plaster of Paris is not calcium carbonate.
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