INTERACTIVE SCIENCE 1B

Transcription

1 INTERACTIVE SCIENCE 1B Workbook Solutions (Enrichment Edition) Chapter 5 THE WONDERFUL SOLVENT WATER Part A Sectional Exercise 5.1 Concept checking p False 2. True 3. False 4. False 5. True Multiple choice p B 2. B 3. C 4. C Questions p (a)(i) A is a filter paper. (ii) B is a filter funnel. (iii) P is called the residue. (iv) Q is called the filtrate. (b)(i) Filtration (ii) Insoluble impurities (iii) Soluble impurities and micro-organisms 2. (a) Distillation (b) 5.1

2 (c) (i) Thermometer (ii) Condenser (d) Water changes into steam. (e) To cool down/condense steam into water. (f) Distilled water 5.2 Concept checking p False 2. True 3. True 4. True 5. False Multiple choice p B 2. C 3. A 4. A 5. C Questions p (a) Ozone can be used to sterilise water. (b) Ozone is used to sterilise water in swimming pools. 2. Chlorination used in water treatment plants. Using ozone in swimming pools. Using ultraviolet light in drinking water fountains. (Or any three reasonable answers.) 5.2

3 3. (a) To remove large solid substances. (b) To remove heavy and insoluble solid substances. (c) To remove small and insoluble solid substances. (d) To sterilise the water by killing micro-organisms. (e) To help us prevent tooth decay. 5.3 Multiple choice p A 2. B 3. D 4. C 5. A Fill in the blanks p.30 (a) (i) evaporate (ii) water vapour (iii) evaporation (b) (i) water vapour (ii) condensed (iii) cold (iv) condensation (c) clouds (d) (i) rain (ii) water cycle Questions p (a) The water vapour in the air condensed to tiny water droplets on the cold surface of the spectacles. (b) The water evaporated into the air. 2. (a) Towel B. It has a larger exposed surface area. (b) Sunny, windy and low humidity 5.3

4 5.4 Concept checking p False 2. True 3. False 4. True Multiple choice p D 2. B 3. B 4. D 5. C Question p.32 The oils and detergents poured into the sink in the Home Economics room. The coloured water or glue poured into the sink in the Art room. The chemicals poured into the sink in the Science Laboratory. (Or any three reasonable answers.) 5.5 Fill in the blanks p (a) solution (b) solute (c) solvent 2. (a) undissolved (b) saturated 3. (a) more (b) solubility Multiple choice p C 2. B 3. C 4. C Questions p (a) Water (b) Powder P (c) Saturated solution (d) Add more water. 5.4

5 Heat up the solution. (Or any two reasonable answers.) 2. Use packets of sugar grains/powder. Stir the tea. (Or any two reasonable answers.) 3. (a) Syrup/Sugar solution (b) Sugar in solid form dissolves slowly in cold water (solution), while syrup (sugar solution) mixes with cold water quickly. 5.6 Multiple choice p D 2. C 3. B 4. B 5. B Fill in the blanks p.35 (a) regular (b) flat (c) cooling (d) evaporating (e) Large Questions p (a) Saturated solution (b) Cool down the saturated solution quickly by putting the beaker in an ice bath./ Heat to evaporate some water from the saturated solution and let it cool down. (c) Hang a small piece of table salt crystal in a beaker of saturated table salt solution and cover with a piece of paper. (d) 2. (a) 60 g 5.5

6 (b) 20 g (c) (i) 70 g/100 cm 3 water (ii) 45 g/100 cm 3 water (d) (70 45) g 5.7 Multiple choice p D 2. A 3. A 4. D 5. B Question p.38 (a) (i) (ii) (iii) (b) solvent Y (c) Potential hazard: The solvent is flammable./it may cause dizziness or difficult in breathing./it is harmful to our skin. (Or any reasonable answers.) Safety precaution: Keep away from fire./ensure good ventilation./avoid direct contact with skin. (Or any reasonable answers.) Part B Integrated Exercise Concept checking p True 2. False 3. False 4. False 5. True 6. False 7. True 5.6

7 8. True 9. False 10. True Multiple choice p B 2. A 3. A 4. B 5. B 6. C 7. B 8. B 9. D 10. C 11. B Questions p (a) 5.7

8 (b) No, it still contains soluble impurities and micro-organisms. (c) He should distill the water. (d) 2. (a) (i) A: Evaporation B: Condensation C: Cloud formation D: Raining (ii) Process A / Evaporation (iii) The energy comes from the Sun. (b) It is because only the water from the sea evaporates and condenses to become rain, the salt is left behind in the sea. (c) No, the salt dissolves in water and cannot be filtered away. (d) It is too expensive. 3. (a) Diagram B (b) Sunlight, wind and large exposed surface area of clothes (or any three reasonable answers) 4. (a) The moving air/wind blows on the wet hands, making the water evaporate quickly. (b) Make it blow warm air. Make it blow stronger. 5. (a) Domestic waste, agricultural waste, industrial waste, oil spills and rubbish (b) Domestic waste and industrial waste (c) Do not use too much cleaning agents. Do not use too much sauces/oil. (Or any two reasonable answers.) (d) Set up laws and regulations. Treat sewage before discharging it into the sea. Educate the public the importance of controlling water pollution. (Or any three reasonable answers.) 6. (a) 69 m 3 5.8

9 (b) 129 days (c) 69 m 3 / (4 129) = m 3 /day (= L/day) (d) (i) 20.0 m 3 (ii) 20.0 m 3 / (4 30) = m 3 /day (= L/day) (e) ( ) m 3 /day = m 3 /day or ( ) /day = 33.0 /day (f) (i) The rate of water charges ($ per m 3 ) is lower. (ii) To encourage us to use less water/save water. Part C Concept Diagram p soluble impurities 12. agricultural waste 22. evaporating 2. insoluble impurities 13. industrial waste 23. high 3. micro-organisms 14. oil spills 24. small 4. sedimentation 15. rubbish 25. stirred 5. filtration 16. laws and regulations 26. rain 6. distillation 17. chemical waste 27. clouds 7. chlorination treatment 28. condensation 8. ozone 18. education 29. moving 9. ultraviolet light 19. solution 30. large 10. fluoridation 11. domestic waste 20. solutes 21. cooling 31. high 32. low Part D Reading Comprehension p (a) The water these children drink is dirty and unsafe/is contaminated/carries diseases. (b) Cholera, typhoid and hepatitis (c) Trachoma is an eye disease caused by dirty water. (It may cause blindness). (d) They may need to walk for 5 hours to collect water for their families. (e) By using water purification tablets. (f) by drilling for fresh underground water. (g) Donate/give money to them (through suitable organizations such as UNICEF). (Or other reasonable answers.) Part E Little Einstein s Corner p (a) The sugar is in fine powder form. (b) (i) 1. the type of sugar (with different sizes of sugar grains) 2. the weight of sugar, the volume of water, the temperature of water, the rate of stirring. 3. the time taken for the sugar to dissolve (ii) A balance (to weigh the sugar), a measuring cylinder (to measure the volume 5.9

10 2. (a) of water), a stopwatch (to take the time), a glass rod/stirrer (to stir the water), a beaker/cup (to hold the water for dissolving the sugar) (b) 10.0 g (c) (i) The solubility of the two solids increases (i.e. more solids are dissolved) as the temperature of water increases. (ii) The solubility of solid B increases much faster than the solubility of solid A. (d) (i) About 77.5 C (ii) About 35.0 g/100 cm 3 water (e) (i) 18.0 g 60/100 = 10.8 g (ii) 10.0 g 60/100 = 6.0 g (iii) ( ) g = 4.8 g (f) (i) Solid B crystallises because 100 cm 3 of water can dissolve at most 7.0 g of solid B at 20 C while 33.5 g of solid A can be dissolved in the same volume of water. (ii) ( ) g = 13.0 g (iii) Filtration 5.10