Sections 10.1 & 10.2
A. Concept checking p.25
1. True
2. False
3. False
4. True
5. False
6. True
B. Multiple choice p.25
1. B
2. D
3. B
4. C
5. B
6. A
7. A
C. Fill in the blanks p.27
1. sour
2. opposite
3. (a) bitter
(b) soapy / slippery
4. (a) sodium hydroxide
(b) potassium hydroxide
(c) protective gloves / gloves
5. (a) slow running water / the tap
(b) 10
Section 10.3
A. Multiple choice p.27
1. B
2. D
3. C
4. A
5. A
B. Fill in the blanks p.28
1. (a) blue
(b) red
(c) red
(d) blue
(e) Neutral
2. (a) degree
(b) acidic
(c) neutral
(d) alkaline
C. Questions p.29
1. (a) ii
(b) iv, vii
(c) v, vi
(d) iii
(e) i, viii
2. (a) Its pH value may be 2.5 – 5.
(b) Carbon dioxide is boiled off. There is no / less carbonic acid. The amount of acid in the drink decreases, so the drink becomes less acidic and its pH value increases.
3. (a) Use a piece of pH paper / a pH meter / universal indicator solution to measure its pH value.
(b) Silk Liquid Soap
(c) ABC Liquid Soap
(d) Silk Liquid Soap has a pH value of 5.5, which is the same as the pH value of healthy skin. It is better for our skin. Soap solution has a pH value of 10, which is significantly higher than the pH value of our skin and may irritate / harm our skin.
Integrated Exercise
A. Concept checking p.45
1. True
2. False
3. True
B. Multiple choice p.45
1. C
2. B
3. B
4. C
C. Questions p.48
1. (a) Solution A: vinegar
Solution B: rainwater
Solution C: soap solution
Solution D: lime water
(b) Its pH value may be between 8.8 and 12.3.
2. (a) Indicators P and T
(b) Indicators Q and R are blue in ammonia.
(c) Indicator Q is yellow in both acids. Indicator S is colourless in both acids.
(d) Indicator P is yellow in ethanoic acid and in sodium hydroxide.
(e) Indicator P is red in a solution with a pH value equal to or less than 2. Indicator T is yellow in a solution with a pH value in between 2 and 8. If a solution looks red after adding indicator P and yellow after adding indicator T, it means that the solution has a pH value of about 2.
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