C1.14a Ban chlorine!
Toxic gas in swimming pool disaster! Chlorine was implicated in a disaster yesterday when the steel beams in the roof of Northtown swimming pool collapsed, showering swimmers below with chunks of concrete and debris. Engineers said that chlorine compounds used to keep the water clean had corroded and weakened the beams. Incidents have occurred in other places when chlorine compounds weakened joints between plastic water pipes, causing thousands of pounds worth of water damage to computer equipment below. Chlorine gas is toxic. If you breathe it, it dissolves in the moisture in your throat and lungs and forms hydrochloric acid.
Hydrochloric acid can also form in the moisture in your eyes. Chlorine disinfectants can also react with other substances in water or sweat to form harmful by-products. Chlorine gas has even been used in wars to kill and injure troops. There have been accidents in which clouds of chlorine gas have escaped from factories or crashed chemical tankers. People have been killed or injured in these accidents, and whole towns have had to be evacuated. So why is this dangerous substance allowed to be used? Join our campaign to ban all products containing chlorine! Click on the link below.
1
How can you test a sample of gas to find out whether or not it is chlorine?
2
a
Why are chlorine compounds used in swimming pools?
b
Why are chlorine compounds used to treat drinking water?
c
Which of these two uses is the most important? Explain your answer.
d
Why is the fact that chlorine is toxic important for these uses?
3 4 5
The writer of the news article above suggests that a non-toxic compound should be used to treat water. Suggest why this might not be possible. Write down two other uses of chlorine. Reports in the media can often report scientific facts inaccurately, or show bias. All of the facts in the above article are true. a
What is the difference between a ‘fact’ and an ‘opinion’?
b
Explain how the article shows bias.
c
Write an extra paragraph to add to the article to correct the bias.
© Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
C1.14b A new factory You do not need to remember the details on this sheet for your exam but you could be asked to apply your knowledge to unfamiliar situations. Almost everything we buy has been made or grown using products of the chemical industry. Chlorine is an important element in this industry. 1
The information below is about seven products of the chemical industry and their uses: Bleach (sodium hypochlorite) – cleaning, killing bacteria Glycerol (propan-1,2,3-triol) – making pharmaceuticals PVC (polychloroethene) – building and medical industries Tetrachloroethene – dry cleaning
DDT (dichlorodiphenyltrichloroethane) – insecticide Phenol (hydroxybenzene) – making drugs and plastics Teflon® (polytetrafluoroethene) – non-stick coatings
Some of these products have chlorine in their structures. The rest do not have chlorine in their structures, but were made using compounds of chlorine. Which products do you think have chlorine in their structures? Explain your answer. A chemical company wants to build a new factory to make chlorine. They need to consider several different factors when choosing a site for their factory. One location being considered is Kinlochleven, a small town in Scotland. There is a reservoir above the town, with pipes to carry water down the hillside. The water from the reservoir was once used to generate electricity for an aluminium factory that is now closed. Kinlochleven is on the coast. 2
Suggest why a location on the coast is important.
3
Suggest why the company is looking for a location with a supply of cheap electricity.
4
There is no railway line at Kinlochleven, and 10 miles of narrow road linking it to the main roads. Suggest some advantages and disadvantages of this remote location: a
for running the factory
b
in the case of an accidental release of chlorine.
Extra challenge 5
Find Kinlochleven on a map. Why is this location: a
likely to be a problem for the company to recruit workers to work in the factory
b
likely to cause protests from visitors and tourism companies?
© Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
C1.14c Electrolysis questions Name 1
Class
Date
This diagram shows the apparatus used for electrolysis. Label the diagram using words from the box.
electricity supply electrodes sea water
6 V d.c. supply
2
What kind of electricity supply is used for electrolysis? Tick one box. F alternating current
3
F direct current
You can test for chlorine using damp litmus paper. Complete the sentences to describe what happens if the gas you are testing is chlorine. Use words from the box.
red
Hold damp _______ litmus paper in the gas. If the gas is chlorine the litmus
blue
white
paper will turn ___________, and then turn ________. 4
You can carry out electrolysis using hydrochloric acid. Which two gases are produced by the electrolysis of hydrochloric acid? __________________________________________________________________
5
Write down three uses for chlorine. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________
6
a
Which of these hazard symbols would you see on a container of chlorine?
b
What is the meaning of the symbol you have ticked? _______________________________________________________________
Š Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.
C1.14d Electrolysis and chlorine Chlorine can be produced by the electrolysis of sea water. 1
Draw a labelled diagram to show how to produce chlorine from sea water.
Chlorine reacts with hydrogen to form hydrogen chloride gas. When this is dissolved in water it forms hydrochloric acid. Hydrochloric acid can be split up into chlorine and hydrogen again. 2
3
a
Write a word equation to show the reaction of chlorine and hydrogen.
b
Write a balanced equation to show this reaction.
You can write balanced equations that include hydrogen chloride gas, or hydrochloric acid. Both of these compounds have the formula HCl. How can you show the difference in a balanced equation?
4
How can hydrochloric acid be split up to form hydrogen and chlorine?
5
What hazard symbol should be shown on containers of chlorine?
6
a
Describe three uses of chlorine.
b
Explain how one of these uses is related to your answer to question 5.
7
Suggest why many people would not want a new chemical factory making chlorine to be built near their town.
Extra challenge 8
Use the Internet to find a copy of Wilfred Owen’s poem Dulce et decorum est. This describes a gas attack in the First World War. a
How does the gas affect the soldier who did not put on his gas mask in time?
b
Do you think gas should be used in war? Is it any worse than killing enemy soldiers using guns?
Š Pearson Education 2010. Edexcel GCSE Science Activity Pack This document may have been altered from the original.