2020同步外研英语必修1新突破(课件+讲义+精练):Module 5.doc
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1、1有两种变化:化学变化和物理变化,那么你知道化学变化和物理变化的区别吗?Chemical Change and Physical ChangeThere are two kinds of changechemical change and physical change.In a chemical change, there is always a new substance formed.Breaking up water into hydrogen and oxygen is a chemical change.In each of the chemical change at least
2、 one new substance is formed.A change is not a chemical change if it doesnt form a new substance.Physical changes are very common, too.There are many examples.You can make a physical change by tearing a piece of paper into two, or by cutting a piece of iron with a lathe.Here the paper is still paper
3、, and the iron is still iron.Another way of making physical change is dissolving something in water.When you dissolve salt in water, the salt disappears.You may think that a new substance has been formed.But in fact there is no new substance.The salt is still salt.You can still taste it.So the disso
4、lving of anything is a physical change.When water freezes, the change is also a physical one.The water changes from liquid to solid.But it is still the same substance.That is why the freezing of anything is a physical change.2And people often tell the differences between a chemical change and a phys
5、ical change through some experiments.We should try to explore the magical science world by doing experiments by ourselves.阅读障碍词1hydrogen n氢气2tear v撕扯3lathe n车床4freeze v结冰;冷冻5magical adj.魔力的诱思导读根据短文内容,判断正误(T/F)1In a chemical change, there is always a new substance formed.(T)2Breaking up water into hy
6、drogen and oxygen is a physical change.(F)3Water changing from liquid to solid is a chemical change.(F) Section Warming Up, Prereading (b) in water that has no air in it (airfree water); (c) in ordinary water.Apparatus:3 clean iron nails; test tubes; test tube holder; cotton wool; oil; Bunsen burner
7、.目的:发现铁是否在下列状态下生锈:(a)在干燥的空气中;(b)在没有空气的水中(无空气水);(c)在普通的水中。仪器:三颗洁净的铁钉、试管、试管夹、棉花、油、本生灯(即煤气灯)。助读讲解 To find out if iron rusts 是目的状语,其中 if 意为“是否” ,引导宾语从句。that has no air in it 是 that 引导的定语从句,修饰先行词water。Iron in dry airMethod(1)Put some iron nails at the bottom of a test tube.(2)Push some cotton wool down t
8、he tube.(3)Leave the tube for one week.ResultAfter one week, the nails have not rusted.ConclusionIron does not rust in dry air.Iron in airfree waterMethod(1)Halffill a test tube with water.(2)Boil(煮沸) the water for three minutes.(This makes sure there is no air in the water.)(3)Put two or three clea
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