Module 5 A Lesson in a Lab 英汉对照 课件 （外研必修1）.pptVIP

* * Passage A It is hard to think of a world without metals.Different metals have different uses，for example，steel is used in cars，and iron is used in electrical equipment.When we use metals，it is important to know how they react with different substances，for example，water and oxygen.The reaction of metals with these substances can be put in order.Here is a table with the metals that react most at the top，and the metals that react least at the bottom. Metal Heated in oxygen Reaction with water or steam Potassium Burns to form an oxide* Reacting with cold water Sodium Calcium Magnesium Reacting with steam Aluminium Zinc Iron Reacts slowly Partial reaction Copper Partial reaction No reaction * an oxide＝another substance＋oxygen Passage B A Simple Scientific Experiment Below is a description of a simple scientific experiment.It shows us how iron reacts with air and with water. Aim: To find out if iron rusts (a) in dry air；(b) in water that has no air in it (air-free water)；(c) in ordinary water. Apparatus: 3 clean iron nails；test tubes；test tube holder；cotton wool；oil；Bunsen burner. Iron in dry air Method (1) Put some iron nails at the bottom of a test tube. (2) Push some cotton wool down the tube. (3) Leave the tube for one week. Result After one week，the nails have not rusted. Conclusion Iron does not rust in dry air. Iron in air-free water Method (1) Half-fill a test tube with water. (2) Boil the water for three minutes.(This makes sure there is no air in the water.) (3) Put two or three clean nails in the water. (4) Add some oil to the water.This will keep air out of the water. (5) Leave the tube for one week. Result The nails do not rust in the tube with air-free water. Conclusion Iron does not rust in air-free water. Iron in ordinary water Method (1) Half-fill a test tube with water and add two or three clean nails. (2) Leave the tube for one week. Result The nails rust in the tube with ordinary water. Conclusion Iron rusts in ordinary water. 文章A 很难想象一个没有金属