CHAPTER 6: States of matter
Worksheet 6.4
Particles in our lives
Science Quest 8: pages 226–30
Answers
Gases and soft drinks
1. A soft drink contains particles of carbon dioxide gas dissolved under pressure in flavoured water. If
you increase the pressure, more of the carbon dioxide dissolves in the water. When the lid is
removed, bubbles of the gas start to escape from the water and the bottle. This gas can be collected
in a balloon as shown in the diagram.
(a) Explain why carbon dioxide starts to bubble out of the soft drink as
the lid is removed.
The pressure of the carbon dioxide gas above the liquid is
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released when the lid is opened. This sudden drop in pressure
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causes the dissolved carbon dioxide to bubble out as it is no
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longer under such high pressure.
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(b) Predict how the volume of gas in the balloon changes if the bottle is
placed in a beaker of hot water. Explain your answer.
The hot water will drive more gas out of the soft drink and
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so the balloon will increase in volume.
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(c) The balloon of gas is then detached and a gas pressure gauge is
attached. The balloon is then placed in a beaker of ice blocks.
(i) Predict how the volume of the balloon will change as the
apparatus cools down.
The cooling of the drink will assist more gas to dissolve
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and thus the volume of the balloon will decrease as
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there is less gas in the balloon.
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(ii) Predict how the reading on the pressure gauge will change.
Explain your answer.
The reading on the pressure gauge will drop as some
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gas will dissolve in the drink at lower temperatures.
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The water cycle
2. Use the water cycle diagram to describe what happens to the particles of water throughout the cycle.
Liquid water in the ocean or lakes will evaporate into
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the air using the heat energy from the sun. In the
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cooler upper atmosphere the gaseous water vapour
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condenses into droplets that form clouds. Eventually
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the drops become heavy enough to fall down to the
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ground as rain. The rain washes over the surface of
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the ground and finds its way to the lake or ocean
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once again.
© John Wiley & Sons Australia, Ltd
Science Quest 8 Student Workbook