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起止时间:2021-03-31到2021-07-26
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Chapter 2. Purification of Sodium Chloride Quiz-Chapter 2. Purification of Sodium Chloride
1、 In the experiment of purification of sodium chloride, in which step can potassium ion be removed？
A:Dissolution and filtration
B:Adding barium chloride solution
C:Adding sodium carbonate solution
D:Evaporation and crystallization
答案: Evaporation and crystallization
2、 In the experiment of purification of sodium chloride, the filtrate is transferred to an evaporating dish and evaporated until the solution is in what state?
A: Boiling starts
B:Crystal film appears
C:Be a thin paste
D:Evaporate to dryness
答案: Be a thin paste
3、 What color is the precipitate produced in the identification reaction of magnesium ion?
A:Blue
B: Green
C:Brown
D: Pink
答案: Blue
4、 In what medium should the identification of calcium ion be carried out？
A:Hydrochloric acid
B:Sodium hydroxide
C:Acetic acid
D:Deionized water
答案: Acetic acid
5、 In which medium should the identification of magnesium ion be carried out?
A:Alkaline
B: Acidic
C:Neutral
D:All above
答案: Alkaline
6、 In the experiment of purification of sodium chloride, the filtrate was evaporated, concentrated and evaporated to dryness, and then the purified sodium chloride was obtained.
A:正确
B:错误
答案: 错误
7、 When using the tray balance to weigh the reagents, the objects should be placed on the left and the weights should be placed on the right.
A:正确
B:错误
答案: 正确
8、 In the experiment of purification of sodium chloride, 2 mol/L hydrochloric acid was used to adjust the pH of the solution to 6-7 before evaporation.
A:正确
B:错误
答案: 错误
9、 In the experiment of purification of sodium chloride, when barium chloride is added into the solution, white precipitate is formed, which indicates the existence of sulfate ion in the solution.
A:正确
B:错误
答案: 错误
10、 In the experiment of purification of sodium chloride, sulfate ions can be removed by non-toxic calcium chloride solution instead of barium chloride solution.
A:正确
B:错误
答案: 错误
Chapter 3. Purification of Copper Sulfate Quiz-Chapter 3. Purification of Copper Sulfate
1、 When adding 6 mol/L ammonia to copper sulfate solution, the green precipitate appears first, then the precipitate dissolves and turns into blue solution. What is the green precipitate?
A:Copper hydroxide
B:Copper dihydroxosulphate
C:Tetraammine copper (II) ion
D:Hexaammine copper (II) ion
答案: Copper dihydroxosulphate
2、 In the experiment of purification of copper sulfate, what pH value should be adjusted before the filtrate is evaporated and concentrated?
A:7
B:1-2
C:4
D:14
答案: 1-2
3、 In the experiment of purification of copper sulfate, in order to remove iron and not reduce the yield of the product, what should be the pH value of the solution?
A:7
B:1-2
C: 4
D:14
答案: 4
4、 In the experiment of purification of copper sulfate, what solution should be used to adjust the pH of the solution？
A:Sodium hydroxide
B:Potassium hydroxide
C:Copper hydroxide
D:Copper dihydroxosulphate
答案: Sodium hydroxide
5、 In the copper sulfate purification experiment, if the solution in the evaporating dish turns green during evaporation, what is the reason?
A:Copper ion hydrolyzes.
B:The temperature is too high.
C:The impurities are not removed completely.
D:The evaporation is too dry and the crystal water is lost.
答案: Copper ion hydrolyzes.
6、 In the experiment of purification of copper sulfate, the filtrate was evaporated, concentrated and evaporated to dryness to get the purified copper sulfate
A:正确
B:错误
答案: 错误
7、 In the experiment of purification of copper sulfate, the pH should be adjusted above 4 to remove iron ion.
A:正确
B:错误
答案: 错误
8、 Chemical reagents are usually divided into four grades according to the purity.
A:正确
B:错误
答案: 正确
9、 Crude copper sulfate usually contains soluble impurities such as ferrous sulfate and ferric sulfate, which can be removed by hydrolysis and filtration after adjusting pH.
A:正确
B:错误
答案: 错误
10、 In the experiment of purification of copper sulfate, except for ferrous ion and iron ion, other trace soluble impurities are removed by remaining in the mother liquor.
A:正确
B:错误
答案: 正确
Chapter 4. Acid-Base Reaction and Buffer Solution Quiz-Chapter 4. Acid-Base Reaction and Buffer Solu
1、 What can be prepared as a buffer solution?
A:HCl and NaOH (excess)
B:HCl and NH3·H2O (excess)
C:HAc (excess) and HCl
D:NaOH and NH3·H2O (excess)
答案: HCl and NH3·H2O (excess)
2、 In general, what is the buffer solution?
A:Solution of weak acid and weak base salt
B:Solution of weak acid or weak base and its salt
C:Solution with constant pH value
D:Solution with constant ionization degree
答案: Solution of weak acid or weak base and its salt
3、 What is the most important buffer pair in human plasma?
A:
–
B:
–
C:
–
D:
–
答案: –
4、 What is wrong with the following description of buffer solution?
A:When the temperature is constant, pKa and buffer ratio are the most important factors affecting the pH value of buffer solution.
B:After the buffer solution was diluted with water, the pH value and buffer capacity remained unchanged.
C:The effective buffer range of buffer solution is pKa±1.
D:hen the buffer ratio is constant, the larger the total concentration is, the larger the buffer capacity is.
答案: After the buffer solution was diluted with water, the pH value and buffer capacity remained unchanged.
5、 What pH of the standard solutions should be used for calibration when measuring acid solution with acidity meter?
A:6.86 and 4.00
B:6.86 and 9.18
C:4.00 and 9.18
D:All above.
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