F2 Workbook Ch10 Integrated Exercise Answers

Integrated Exercise

A. Concept checking                                     p.45

1.          True

2.          False

3.          True

8.          False

9.          True

10.      False

B. Multiple choice                                          p.45

1.          C

2.          B

3.          B

4.          C

5.          A

6.          A

7.          A

8.          D

9.          A

10.      C

11.      A

12.      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.

3.     (a)    Red

        (b)    Concentrated hydrochloric acid gives off an acidic vapour. The acidic vapour dissolves in the water in the moist blue litmus paper and turns the litmus paper red.

4.     (a)    Colourless gas bubbles are given out.

        (b)    (i)     The lime water turns milky.

                (ii)    The gas released in the reaction is carbon dioxide.

        (c)    Marble / calcium carbonate / other carbonates

5.     (a)   

       

       

        (b)    (Take out the test tube containing the gas from the set-up in (a).) Put a burning splint near            the mouth of the test tube. If the gas burns with a ‘pop’ sound, it is hydrogen.

        (c)    (i)     Hydrogen gas will be given out at a slower rate.

                (ii)    There will be no reaction. / No hydrogen gas will be collected.

6.     (a)    The air in Sai Kung is the least polluted. The pH value of the rainwater sample collected              there was 5.5, which is closest to the pH value of 5.6 of clean / normal rain.

        (b)    (i)     The air in Tsuen Wan and Causeway Bay is the most polluted. The pH

                values of the rainwater samples collected in these areas were the lowest among

                the areas shown. This means that the rainwater was highly polluted by acidic

                pollutants / sulphur dioxide and nitrogen oxides and was the most acidic.

                (ii)    Tsuen Wan: factories and motor vehicles (Tsuen Wan is an industrial area

                with heavy traffic.) Causeway Bay: motor vehicles (Causeway Bay has heavy

                traffic.)

        (c)    (i)     The rainwater becomes more acidic during winter.

                (ii)    The southern part of Guangdong is heavily polluted with acidic pollutant

                gases / sulphur dioxide and nitrogen oxides released from the factories and power

                stations there. When these gases are blown from the north-east to Hong Kong in

                winter, the rainwater collected in Sheung Shui and Sai Kung (located in

                north-eastern parts of Hong Kong) becomes more acidic and the pH value of

                rainwater decreases.