Common Chemical Compounds and Their Uses Quiz: Clerkship GK
A little practice. A step forward.
10 questions on the names, formulas and uses of everyday chemical compounds, each with an explanation. 📖 Read the detailed topic
What are the chemical name and formula of baking soda?
Baking soda is sodium hydrogen carbonate (sodium bicarbonate), NaHCO₃. On heating or with an acid it gives off CO₂, which makes cakes and bread rise. Na₂CO₃ is washing soda, NaOH is caustic soda and NaCl is common salt.
- Baking powder = baking soda + tartaric acid
- Mildly basic, so used in antacids
- Found in soda-acid fire extinguishers
- Na₂CO₃ (ধোয়ার সোডা) আর NaHCO₃ (বেকিং সোডা) গুলিয়ে ফেলা সবচেয়ে সাধারণ ভুল
- Baking = bicarbonate (makes it rise), washing = carbonate (cleans)
Heating gypsum gives a compound used for plaster casts on broken bones. Which one?
Gypsum (CaSO₄·2H₂O) heated to about 100°C loses water and becomes Plaster of Paris (CaSO₄·½H₂O). When mixed with water it sets hard again as gypsum, so it is used for casts and statues. Limestone is CaCO₃ and slaked lime is Ca(OH)₂.
- Formula CaSO₄·½H₂O
- Sets hard when mixed with water
- Also used for toys, statues and decorative work
- Gypsum has two waters; Plaster of Paris keeps half a water
Which of these is used to disinfect drinking water?
Bleaching powder (CaOCl₂) releases chlorine, which kills germs in water. It is made by passing chlorine over dry slaked lime and also bleaches cotton and linen. The other three are not used to disinfect water.
- Formula CaOCl₂
- Made from dry slaked lime and chlorine
- Bleaching agent in textile and paper industries
- Bleach = smell of chlorine = kills germs
Which of these removes permanent hardness of water?
Washing soda precipitates calcium and magnesium ions as insoluble carbonates, so the water becomes soft. It is also used in laundry and glass making. Limestone is almost insoluble in water and NaCl does not soften water.
- Formula Na₂CO₃·10H₂O (with water of crystallisation)
- Used in laundry and glassmaking
- More strongly basic than baking soda
- Washing soda = cleans and softens hard water
What is 'dry ice'?
Dry ice is solid CO₂. It does not melt into a liquid but turns straight into gas (sublimation), hence 'dry'. It is used to keep ice cream and food cold.
- Temperature about −78°C
- Sublimes directly to gas
- Used to keep food cold
- Solid CO₂ = dry ice
Which acid causes the sting of an ant bite?
Ant and bee stings contain formic (methanoic) acid, so a mild base such as baking soda soothes the bite. Acetic acid is in vinegar, citric in lemon and lactic in curd.
- Vinegar: acetic acid
- Lemon: citric acid
- Curd: lactic acid
- Tamarind: tartaric acid
- Formic comes from Latin formica, 'ant'
| Source | Acid |
|---|---|
| Vinegar | Acetic acid |
| Lemon | Citric acid |
| Curd | Lactic acid |
| Tamarind | Tartaric acid |
| Ant sting | Formic acid |
| Tomato | Oxalic acid |
The main ingredient of the antacid 'milk of magnesia' is:
Milk of magnesia is a suspension of magnesium hydroxide, Mg(OH)₂, in water. It is a mild base that neutralises excess HCl in the stomach. NaOH and Ca(OH)₂ are unsuitable to swallow and HCl is itself an acid.
- Antacid = mild base
- Stomach acid is HCl
- Neutralisation gives salt and water
- Milk of magnesia = Mg(OH)₂
What is the formula of blue vitriol?
Blue vitriol is copper sulphate pentahydrate, CuSO₄·5H₂O. Its blue colour comes from the water of crystallisation; on heating it loses water and turns white. FeSO₄·7H₂O is green vitriol and ZnSO₄·7H₂O is white vitriol.
- Used as a fungicide (Bordeaux mixture)
- Turns white on heating
- Anhydrous CuSO₄ turns blue with water, a test for water
- সব ভিট্রিয়লের শেষে SO₄ ও জলের অণু আছে; রং আর ধাতু মিলিয়ে মনে রাখুন
- Copper = Cu = blue
| Common name | Formula | Colour |
|---|---|---|
| Blue vitriol | CuSO₄·5H₂O | Blue |
| Green vitriol | FeSO₄·7H₂O | Green |
| White vitriol | ZnSO₄·7H₂O | White |
Which of these is NOT obtained by electrolysis of brine (chlor-alkali process)?
Electrolysis of brine (aqueous NaCl) gives chlorine at the anode, hydrogen at the cathode and NaOH (caustic soda) in the solution. Oxygen is not a product.
- Anode: Cl₂
- Cathode: H₂
- NaOH in solution
- NaOH is used in soap and paper making
- Chlor (Cl) + alkali (NaOH): the name gives the answer
Which of these fertilisers has the highest percentage of nitrogen?
Urea, CO(NH₂)₂, contains about 46% nitrogen, the highest of these. Ammonium nitrate has about 35%, ammonium sulphate about 21% and DAP about 18%.
- Urea: about 46% N
- Ammonium nitrate: about 35% N
- Ammonium sulphate: about 21% N
- DAP: about 18% N plus phosphorus
- Urea is the most nitrogen-rich fertiliser
Nitrogen in fertilisers (approx.)
📊 Topic Analysis
10 questions on the names, formulas and uses of everyday chemical compounds, each with an explanation.
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