Chapter 4 Review Answers

Chapter 4 Review Answers
1. (a) Concentrated means that there is a large amount of solute per volume of solution, while
dilute means the opposite.
(b) An acid turns blue litmus paper red, is corrosive, tastes sour, and neutralizes bases. A base
turns red litmus paper blue, is corrosive, tastes bitter, feels slippery, and neutralizes acids.
2. Bases turn red litmus paper blue but do not change the colour of blue litmus paper.
3. Scripts will vary but should include the following points describing the pH scale:
• used to classify substances as acidic, basic, or neutral
• scale goes from 0–14
• acids found from 0–7
• bases found from 7–14
• neutral substances found at 7
• substances become more corrosive the farther they are from 7
• substances found at the ends of the scale are extremely corrosive and require special handling
4. Neutralization means to make a substance neither acidic nor basic.
5. Rust is the product of iron reacting with oxygen (corrosion).
6. Your aunt (cousin’s mother) prefers the more concentrated sugar-tea solution (3/cup).
7. As concentration decreases, the amount of solute decreases.
8. A ready-to-use product produces more waste packaging than a concentrated product.
True for Acids
(a) sour taste
(b) bitter taste
True for Bases
(c) speeds up corrosion
(d) soaps are an example
True for Both
Acids and Bases
(e) can be detected with an indicator
(f) is often corrosive
10. Scientists use indicators to identify acids and bases because it is safer and more accurate than
tasting them.
11. An apple with a pH of 3 is an acid.
12. Because lemon juice is an acid, it can neutralize the smelly base of fish oil.
13. Factors that affect corrosion include:
• pH
• salts
• humidity
• temperature
14. Acids speed corrosion.
15. Any homemade indicator could be used, such as red cabbage juice, hydrangea, cranberry
juice, or lichen.
16. (a) tomatoes = acid
(b) lye = base
(c) stomach acid = acid
(d) bananas = acid
(e) blood = neutral (slightly basic)
(f) milk of magnesia = base
(g) ammonia = base
(h) eggs = neutral (slightly basic)
17. The scale should go from 0–14. Acids are found from 0–7, neutral substances at 7, and bases
from 7–14.
18. The advantages of buying a product with very little or no solvent include:
• takes up less space
• requires less packaging
• weighs less
19. The solution that changed the colour of copper and turned blue litmus paper red was an acid.
20. Baking soda is a base so it will help neutralize the acids that are causing the heartburn.
21. Realistic ideas on how to reduce the amount of garbage thrown out will vary but might
• using more concentrated products
• recycling
• avoiding over-packaged products
22. (a) Rain with a pH of 3.2 will cause more corrosion than rain with a pH of 5.2.
(b) Storing a car in a heated garage will cause more corrosion than storing in a non-heated
garage during the winter.
(c) Living on the coast will cause more corrosion than living near a desert.
23. Flowcharts of the process of making frozen concentrated orange juice will vary but should
• extracting juice from oranges
• evaporating some of the solvent
• freezing the resulting concentrate
24. Strategies to reduce the pain of an ant bite will vary but may include:
• washing the area with soap (a base)
• applying a base such as baking soda