双语教案
2020-03-03 17:48:55 来源：范文大全收藏下载本文
来自九年义务教育初中化学教科书
Properties of Carbon Dioxide
Outline: 1.physical properties of carbon dioxide 2.chemical properties of carbon dioxide 3.Uses of carbon dioxide
15化学1班
谭雪锋 2015364138 2017/4/21Good morning, everyone.Welcome to my claroom.Let’susknow an important gas.Every day we need to breath, what is gas of breath outside? Can you gue it, my dear student?
Yes, it is carbon dioxide.Carbon Dioxide is important for living things, so what important properties does it have? Who can tell me its physical properties?( As some students said, it is…colourle) First,Look at the picture.When carbon dioxide is poured into a paper bag.Watch if the two paper bags still balance.Why?From the experiment we know that carbon dioxide is a colorle gas and the bag fill with carbon dioxide is tilted, which shows carbon dioxide has a higher density than air.That is reason why… Besides,Usually,about 1 volume of carbon dioxide diolve in 1 volume of water.My dear, look at the experiment.Place two burning candles on each of a 2-step holder made of a galvanized iron sheet.Put the holder inside a beaker (as shown in picture ) and pour carbon dioxide along the beaker’s wall.Pay attention to what happens to the burning candles when the carbon dioxide is poured.What does the experiment show? Who can tell me? In the experiment, the candle flame go out.And the candle on the lower step goes out first.The experiment show two things:first, carbon dioxide does not burn, nor help burning; second, carbon dioxide has a bigger density than air.
After learn many properties of carbon dioxide,you may be a little tired.Now,let’s enjoy the interesting experiment.Bubble carbon dioxide into a test tube filled with a solution of purple litmus.Watch how litmus solution changes color.After that, heated it and watch again the litmus changes color.After watch the video, we can easily know the color changed red.Why it can change red? Who knows?(that is because carbon dioxide diolves in water to form carbonic acid(H2CO3)).Good jod!
Ok, let’s continue to watch.When carbon dioxide is blown into a clear limewater, what does it will be? Who can tell me why?(clear limewater become cloudy, because white precipitates of calcium carbonate are made) Yes,you are right.
After know about physical and chemical properties of carbon dioxide, we need to know about its uses.As we know, carbon dioxide is used for put out fires.it is also used in industry for manufacture.and gas fertilizer.Moreover, dry ice can be used to preserve food or artificial rainfall.Last but not important, plants need carbon dioxide during photosynthesis.
Finally, let’s us do a summary.At this cal, we know about carbon dioxide’s physical properties and chemical properties.Besides, we also know the uses of carbon dioxide.and many interesting experiments.Cla is over, thank you!
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