Atoms and atomic theory
point. When liquids are cooled, the crystalline material will form during the process of freezing
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English-for-Chemistry-1-After-lesson-1
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- Lesson 7. SOLUTIONS 7.1 Listening: Standard solutions Complete the paragraph by filling the blanks
| point. When liquids are cooled, the crystalline material will form during the process of
freezing, and the temperature at which this occurs is the freezing point. Under certain conditions solids can directly convert into vapor by the process of sublimation. The reverse process is called deposition. Q1. Choose a short description for each paragraph 1. Introduction of major types of intermolecular forces. 2. Some properties of solids. 3. An overview of intermolecular forces in general. 4. Crystal structures. 5. Some properties of liquids. Q2. - Find sentences containing the relative clause/phrase in the text. - Make 5 sentences with the relative clause/phrase. Q3. - Make groups of students. - Each group prepares 5 questions. - Each group takes turn to ask and answer questions from the other group. Grammar note: Participle phrase/short form of relative clause - Present participle phrase - Past participle phrase English in chemistry 1 – 2017 TS. Nguyễn Tuyết Phương – TS. Trần Thu Phương 20 Lesson 7. SOLUTIONS 7.1 Listening: Standard solutions Complete the paragraph by filling the blanks In this video, we are going to learn three things about standard solutions. - What are they? - How do you make one? - Why? Firstly, a standard solution is a solution of an accurately known …(1)…. Secondly, if you prepare a standard solution, there are few steps you have to follow. Before you make up a standard solution, you should always …(2)… out your volumetric flask with distilled water. This is to remove any contaminants. - Step A: You have to dissolve an accurately known mass of solute in a beaker. You usually use two decimal balance to archive it. - Step B: You have to make sure that the mass is fully …(3)…. Can you think why? Pause the video and continue when ready. You have to make sure that the mass is fully dissolved. Otherwise, its concentration will be incorrect. Did you get it right? - Step C: You have to transfer the solution from the …(4)… to a volumetric flask. You use a volumetric flask to measure the exact volume of water required for a standard solution. You have to add the distilled water into the volumetric …(5)… until it reaches the neck, gently swirling. - Step D: The last few drops of water have to be added …(6)…. So you use a pipette and place the neck of the flask in front of a white tile at eye level. The water line appears curved. When the …(7)… of the curve, called the meniscus, rests on the line marked on the neck of the volumetric flask, you have made your standard solution of accurate volume and a …(8)… concentration. You should invert it a couple of time at this point, just to make sure it is thoroughly mixed. Do not be tempted to top-up the water again. What do you think might happen if you were to add water past this mark? Pause the video and continue when ready. The answer is the …(9)… solution would not be at the right concentration. It would be more dilute than you expected it to be. And the experiment completed with a solution like this would cause your result to be incorrect. English in chemistry 1 – 2017 TS. Nguyễn Tuyết Phương – TS. Trần Thu Phương 21 You may wonder why bother to go to this trouble to make a standard solution and what it is used for? The answer is that having a …(10)… where the concentration is accurately known allows you to do something called titration and calculate the concentration of an unknown solution. Here’s a challenge. Can you remember what a standard solution is and why it might be useful? Pause the video and recap your idea, continue when ready. In summary, a standard solution is a solution of an accurately …(11)… concentration and it can be used to find the concentration of an unknown solution in an experiment called a titration. tải về 0.52 Mb. Chia sẻ với bạn bè của bạn:
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