Hydrogen and Industries
Hydrogen, the lightest and simplest of the elements, has several properties that make it valuable for many industries. It releases more heat per unit of weight than any other fuel. In rocket engines, tons of hydrogen and oxygen are burned, and hydrogen is used with oxygen for welding torches that produce temperatures as high as 4, 000 degrees F and can be used in cutting steel. Fuel cells to generate electricity operate on hydrogen and oxygen. Hydrogen also serves to prevent metals from tarnishing during heat treatments by removing the oxygen from them. Although it would be difficult to remove the oxygen by itself, hydrogen readily combines with oxygen to form water, which can be heated to steam and easily removed. Hydrogen is also useful in the food industry for a process know as hydrogenation. Products such as margarine and cooking oils are changed from liquids to semisolids by adding hydrogen to their molecules. Soap manufacturers also use hydrogen for this purpose. Hydrogen is also one of the coolest refrigerants. It does not become a liquid until it reaches temperatures of -425 degrees F. Pure hydrogen gas is used in large electric generators to cool the coils. In addition, in the chemical industry, hydrogen is used to produce ammonia, gasoline, methyl alcohol, and many other important products.
鲁教版英语八年级上册单元测试-Unit 2
鲁教版英语八下《Unit 7 I’ll help clean up the city parks》word同步测试题（1）
鲁教版英语八年级上册单元测试-Unit 3
鲁教版英语八下《Unit 3 I used to be afraid of the dark》word同步测试题（7）
鲁教版英语八下《Unit 4 Teenagers should be allowed to choose their own clothes》word同步测试题（1）
鲁教版英语八上《Unit 8 Why don’t you get her a scarf》word同步测试
鲁教版英语八下《Unit 1 Have you ever been to an amusement park》word同步测试题（5）
鲁教版英语八上《Unit 6 How long have you been collecting》word同步测试
鲁教版英语八下《Unit 1 Have you ever been to an amusement park》word同步测试题（6）
鲁教版英语八下《Unit 8 Have you packed yet》word同步测试题（2）
鲁教版英语八上《Unit 7 Would you mind turning down the music》word同步测试7套
鲁教版英语八下《Unit 4 Teenagers should be allowed to choose their own clothes》word同步测试题（3）
鲁教版英语八下《Unit 7 I’ll help clean up the city parks》word同步测试题（2）
鲁教版英语八下《Unit 4 Teenagers should be allowed to choose their own clothes》word同步测试题（8）
鲁教版英语八下《Unit 8 Have you packed yet》word同步测试题（1）
鲁教版英语八年级上册期中测试
鲁教版英语八下《Unit 5 I like music that I can dance to》word同步测试题（3）
牛津广州英语八上《Unit 1 Newspapers》word同步练习
鲁教版英语八下《Unit 1 Have you ever been to an amusement park》word同步测试题（2）
鲁教版英语八上《Unit 4 He said I was hard-working》word同步测试4套
鲁教版英语八下《Unit 4 Teenagers should be allowed to choose their own clothes》word同步测试题（7）
鲁教版英语八年级上册单元测试-Unit 1
鲁教版英语八下《Unit 6 Where would you like to visit》word同步测试题（1）
鲁教版英语八下《Unit 3 I used to be afraid of the dark》word同步测试题（6）
鲁教版英语八下《Unit 1 Have you ever been to an amusement park》word同步测试题（3）
鲁教版英语八年级上册单元测试-Unit 4
鲁教版英语八年级上册期末测试
鲁教版英语八下《Unit 3 I used to be afraid of the dark》word同步测试题（8）
鲁教版英语八下《Unit 8 Have you packed yet》word同步测试题（3）
鲁教版英语八年级上册期中测试（一）