2844011
Description
Flashcards by Taylor Smith, updated more than 1 year ago
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Created by Taylor Smith
almost 9 years ago
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| Question | Answer |
| Tests for Water | 1. Anhydrous copper sulphate 2. Cobalt chloride paper |
| Anhydrous copper sulphate | - Changes from white to blue. - Forms hydrous copper sulphate because of water crystallisation (water crystals bond to copper atoms) |
| Cobalt chloride paper | - Changes from blue to pink. - Hydrous cobalt chloride is formed. - Reaction is reversible. |
| Uses of water in the home: | 1. Cleaning 2. Gardening 3. Drinking 4. Cooking 5. As a solvent |
| Uses of water in industry and agriculture: | 1. Hydro-electric power 2. Cleaning 3. Irrigation 4. Coolant 5. Solvent 6. Reactant in the manufacture of chemicals |
| Purification of water | - Water is obtained from surface and ground water. |
| Impurities in surface/ground water | 1. Bacteria 2. Dissolved substances (e.g. iron salts) 3. Debris (e.g. clay, sand) 4. Chemicals which cause taste and odours 5. Acidic substances |
| Impurities in water (cont.) | - Iron is not harmful, but when Fe+2 is exposed to air, it forms Fe(OH)2 (insoluble brown precipitate), which stains laundry, walls and white plumbing. - Fe+3 ions form black compounds with tannic acids in teas and gives it a metallic taste. |
| Steps for water purification | 1. Water is pumped from source to reservoir. 2. Air is added to remove iron compounds. 3. Aluminium sulphate is added to coagulate clay. 4. Water is fed into sedimentation tank where larger particles are left to settle. |
| Steps for water purification (cont.) | 5. Water is passed through sand bed under pressure where particles filter out the impurities. Filters are cleaned by backwashing. 6. Chlorine is added to clear bacteria and algae (HCl and HOCl are formed, HOCl penetrates cell walls by destoring lipids in cell wall and destroying inside structures (germicidal action). |
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