Chapter 3

1. Chapter 3 Test Review

2. Question #1 DESCRIBE one method used separate the following mixtures into the products indicated • Sewage to clean water • Wheat grains to white flour • Petroleum to gasoline

3. Sewage to Clean Water • One method of separating sewage water is to use floating and settling to remove solids, grease and oil. From there the remaining water passes through tanks containing bacteria. Oxygen is bubbled through the mixture and the bacteria breaks down any remaining human waste and plant material. The water settles again and bacteria settles to the bottom to be removed. Finally the water is filtered and chemicals like chlorine are added to kill any remaining organisms.

4. Wheat Grains to White Flour • The grains first need to be purified by passing through a series of sieves to remove any substances such as dust and sand that the grain may have come in contact with. From there the grain is sent through the milling process and sent through more sieves to separate the endosperm, wheat germ and bran. The endosperm is then used to make white flour.

5. Petroleum to Gasoline • A furnace heats the petroleum which causes the components to evaporate. The hot gases rise through the fractional distillation column that cools the gases and allows them to settle at different levels in the column. From there the settled fraction can be further purified to make gasoline used in cars.

6. Question #2 • Suggest a mechanical mixture (not already mentioned) that could be separated into its parts by each of the following methods.

7. A) Sorting – A salad • B) Floating and Settling – Gold dust can be separated from water and other rocks by using settling • C) Using a Magnet – The iron in a pile of scrap metal can be separated from other materials by using a magnet • D) Using a filter or a sieve – Dust and Pollen can be removed from the air by using a filter • E) Dissolving soluble parts of the mixture – A mixture of salt and sand could be separated by dissolving salt in water

8. Question #3 • Why is it important to remove harmful materials from waste before putting the waste into the environment?

9. It is important to remove harmful materials from waste before putting waste into the environment because those harmful materials could damage the environment and poison plants or animals, including humans

10. Question #4 • DESCRIBE one way to separate each of the following mechanical mixtures • A) Air and Dust • B) Paper clips and erasers • C) Mud (Soil and water) • D) Sugar and Sand • E) Sawdust and sand

11. A) A filter can separate dust from air. Air will move through the filter but dust will be trapped. • B) A magnet can be used to separate paper clips and erasers. The magnet will pick up the paper clips, but not the erasers. • C) Settling can separate soil from water. The soil will settle to the bottom of the container of water. You could also use evaporation and evaporate the water from the soil. • D) Dissolving can sort sugar from sand. The sugar will dissolve in water, leaving the sand behind. • E) Floating can separate sawdust and sand. The sawdust will float on water, but the sand will sink.

12. Question #5 • Which methods of separating mechanical mixtures do you think would be most useful in separating garbage that includes compost, waste paper, steel cans and plastic bottles? Explain why?

13. Many separating techniques would be needed to separate this mixture. The waste paper would have to be sorted out by hand. It has similar properties to the compost, but is more easily distinguished. Magnets could be used to separate the steel cans from everything else. The floating and settling could be used to separate bottles. The plastic bottles would float and the compost would sink.

14. Question #6 • Sylvester poured salt into his glass of juice by accident. Can Sylvester remove all the salt by pouring his juice through a filter? Explain why or why not?

15. No, Sylvester won’t be able to remove all the salt from his juice by using a filter. When salt dissovles in water, it breaks into particles too tiny to see. When Sylvester pours his drink through a filter, the tiny particles of salt will pass through along with the juice. The filter might trap some undissolved salt if the juice and salt mixture is saturated (and can’t dissolve any more salt), but it won’t trap all of the salt.

16. Question #7 • Create a flow chart to show the changes that happen in uranium from when it is mined to when it is finally disposed of. Evaluate this process in terms of potential hazards to the environment and living things. Is nuclear power a benefit to society?

17. Nuclear energy is a benefit to society. Like all power generation solutions, it has problems, but it provides energy without creating CO2 emissions

18. Question #8 • People often separate mechanical mixtures in their daily lives. Do you agree or disagree with this statement? Explain why. Use examples and details to support your answer.

19. SAMPLE ANSWER • I agree that people often separate mixtures in their daily lives. We separate mixtures any time we organize our closets, do laundry, cook pasta, or make tea.