63 Oil and Water
To understand the emulsifying process, we must first accept the scientific principle that oil and water do not naturally mix. Quite literally, they find each others presence repulsive. A good illustration of this aversion is homemade oil and vinegar salad dressing.When you shake or beat your salad dressing, you do more than disperse the oil throughout the vinegar: you also break down the oil into droplets minute enough to remain temporarily suspended in the vinegar . The second you stop agitating the dressing, the oil droplets start to combine into units too large to be suspended in the water, and thus slither their way upward, separating from the water in the process. The oil rises to the top and the water sinks because oil has a lower specific density than water. If you want a stable emulsion, you need an emulsifying agent which prevents the oil droplets from combining into larger units. Emulsifying agents occur naturally in many animal substances including egg yolks and milk. An emulsifying agent helps to keep the oil particles from combining in three basic ways. First, the agent coats the oil, serving as a physical barrier between the droplets. Second, it reduces the waters surface tension, which, in turn, reduces the waters ability to repulse oil. Third, the agent gives the surfaces of the oil droplets identical electrical charges; since like charges repel each other the droplets repel each other.
2014秋人教PEP版英语三上《Unit 2 Colours》word第四课时教案
2014秋人教PEP版英语五上《Unit 2 My week》word教学设计
2014秋人教PEP版英语六上《Unit 6 How do you feel》(Part B)教案
2014秋人教PEP版英语三上《Unit 2 Colours》word第三课时教案
2014秋人教PEP版英语五上《Unit 4 What Can You Do》word教案
2014秋人教PEP版小学英语六年级上册教学计划1
2014秋人教PEP版英语三上《Unit 3 Look at me》word第四课时教案
2014秋人教PEP版英语六上《Unit 2 Ways to go to school》word教学设计2
2014秋人教PEP版英语六上《Unit 2 Ways to go to school》word教学设计1
2014秋人教PEP版英语三上《Unit 2 Colours》word第五课时教案
2014秋人教PEP版英语六上《Unit 3 My weekend plan》word第五课时教案
2017人教PEP版英语六年级下册Unit 2《Last weekend》word导学案
2017人教PEP版英语六年级下册全册教案word版(共63页)
2014秋人教PEP版英语六上《Unit 3 My weekend plan》word第二课时教案
2014秋人教PEP版英语六上《Unit 1 How can I get there》word导学案
2017人教PEP版英语六年级下册全册教案word版(共44页)
2014秋人教PEP版英语三上《Unit 4 We love animals》word电子教案
2014秋人教PEP版英语六上《Unit 2 Ways to go to school》word集体备课教案
2014秋人教PEP版英语三上《Unit 3 Look at me》word第三课时教案
2017人教PEP版英语六年级下册Unit 1《How tall are you》word导学案
2017人教PEP版英语六年级下册Unit 3《Where did you go》word导学案
2017人教PEP版英语六年级下册Unit 4《Then and now》word导学案
2014秋人教PEP版英语六上《Unit 4 I Have a Pen Pal》word教案
2014秋人教PEP版英语三上《Unit 3 Look at me》word第二课时教案
2014秋人教PEP版英语六上《Unit 2 Ways to go to school》word教学设计4
2017人教PEP版英语六年级下册《Recycle 1》word导学案
2014秋人教PEP版英语五上《Unit 4 What Can You Do》word教学设计
2014秋人教PEP版英语六上《Unit 1 How can I get there》word教学设计2
2014秋人教PEP版英语六上《Unit 1 How can I get there》word教学设计1
2014秋人教PEP版英语六上《Unit 3 My weekend plan》word第四课时教案
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |