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When the solvent degree of sodium chloride is 36g at 20°C, the mass fraction of solute of saturated sodium chloride solution at this temperature is _______; when 10g water is evaporated from the modified solution and then cooled to 20°C, the mass fraction of solute of the remaining solution _________
When the solvent degree of sodium chloride is 36g at 20°C, the mass fraction of sodium chloride saturated solution at this temperature is 36g/(36g+100g)*100%=26.47%__; when the modified solution evaporates 10g of water and then cools down to 20°C, the mass fraction of remaining solution is 26.47%
The temperature, solubility and mass fraction of solute remain unchanged.
Why does the mass fraction of solute remain unchanged after the solution is heated and evaporated to the original temperature and crystals are precipitated? Premise: saturated solution Try to be as detailed as possible. Why does the mass fraction of solute remain unchanged after the solution is heated and evaporated to the original temperature and crystals are precipitated? Prerequisite: saturated solution Try to be as detailed as possible.
Because the mass fraction of the solute in the saturated solution is the same at the same temperature, the mass fraction of the crystal solute is the same regardless of how it is precipitated, except that some solute is precipitated (so it is no longer solute, but pure crystal)
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- 1. At 10 degrees,131 grams of saturated KCl solution, after evaporation of 10 grams of water, at 10 degrees, the mass of KCl crystals can be precipitated At 10°C,131 g of saturated KCl solution, after evaporation of 10 g of water, the mass of KCl crystals can be precipitated at 10°C
- 2. 200 G of silver nitrate solution at T degree,10 g of precipitated crystal 4 g evaporated,10 g of water evaporated and 6 g washed out,20 g of water evaporated to precipitate crystal mass 200 G of silver nitrate solution at T degree,4 g of precipitated crystals evaporated off 10 g,6 g of precipitated crystals after 10 g of water evaporated, and what is the mass of precipitated crystals after 20 g of water evaporated? 200 G of silver nitrate solution at T degree,10 g of precipitated crystals 4 g evaporated,10 g of water evaporated and 6 g washed out,20 g of water evaporated to precipitate crystal mass 200 G of silver nitrate solution at T degree,4 g of precipitated crystals evaporated off 10 g,6 g of precipitated crystals after 10 g of water evaporated, and what is the mass of precipitated crystals after 20 g of water evaporated? 200 G of silver nitrate solution at T degree,10 g of precipitated crystals 4 g evaporated,10 g of water evaporated and 6 g washed out,20 g of water evaporated to precipitate crystal mass 200 G of silver nitrate solution at T-degree,4 g of precipitated crystals evaporated out of 10 g,6 g of precipitated crystals after 10 g of water evaporated, and what is the mass of precipitated crystals after 20 g of water evaporated?
- 3. At 50.degree. C., the solution of substance A was divided into two equal parts by mass, one part evaporated off 10 g of water to precipitate 4 g of crystal, and the other part evaporated off 20 g of water to precipitate 10 g of crystal Solubility of substance A at 50°C
- 4. 100 G of the solution of the substance A at 50 degrees centigrade was divided into two parts, one part evaporated at constant temperature 10 g of water with 4 g of crystals precipitated, the other part evaporated 20 g of crystals precipitated 20 g, Solubility in 50 degrees Celsius. Must have a process, thank you very much!
- 5. A solution of sodium chloride at 80°C,20 g of water evaporated at constant temperature,2 g of crystals precipitated,20 g of water evaporated at constant temperature,4 g of crystals precipitated, and how many g of crystals precipitated if 35 g of water evaporated at constant temperature? At 20°C, the solubility of sodium chloride is 31 g. At present,500 g of 20% sodium chloride solution is available. If 5 g of sodium chloride crystal will be precipitated at this temperature, what is the mass of water to be evaporated?
- 6. At t°C, the NaOH solution with a% mass fraction of solute was evaporated off mg of water and then recovered to the original temperature. At t.degree. C., the solution of NaOH with a mass fraction of solute was evaporated off mg of water and recovered to the original temperature, and the saturated solution of NaOH with a mass fraction of 2a, and the mass of the original solution was obtained At t°C, the NaOH solution with a% mass fraction of solute is evaporated off mg of water and then recovered to the original temperature. At t.degree. C., the solution of NaOH with a mass fraction of solute was evaporated off mg of water and recovered to the original temperature, and the saturated solution of NaOH with a mass fraction of 2a, and the mass of the original solution was obtained
- 7. Does evaporative crystallization mean increasing the temperature or evaporating the solvent? NaCL is crystallized by evaporation and KNO3 is crystallized by cooling. What about Ca [OH ]2?
- 8. If the temperature is not changed, when 10g of water is evaporated,4g of A crystal (excluding crystal water) will be precipitated. When 10g of water is evaporated again,6g of A crystal will be precipitated.
- 9. After a certain amount of M substance solution is evaporated at a certain temperature by 15 g of water,2 g of crystal is precipitated, another 15 g of water is evaporated, and another 5 g of crystal is precipitated. If another 15 g of water is evaporated, the mass of precipitated crystal is () A.2 g B.5 g C.8 g D. Inability to judge
- 10. How to precipitate potassium nitrate crystals from a mixed solution of potassium nitrate and sodium chloride in a mass ratio of 1:1?
- 11. Judgement: If the laboratory evaporates a sodium chloride solution to precipitate crystals, the mass fraction of the solute must be reduced. Judgement: The laboratory evaporates a sodium chloride solution to precipitate crystals, and the mass fraction of the solute must be reduced.
- 12. At 20.degree. C., the unsaturated solution is divided into two equal parts by mass, one part evaporates 10 g of water and precipitates 4 g of, and the other part evaporates 20 g of water to precipitate 10 g of crystal The solubility of the substance at 20°C is () The answer is 60 g per 100 g of water, Didn't the title say two different copies? Why is it that 10 g evaporates first and 10 g later? And what is 10-4=6g? How did you get here?
- 13. 100G of salt saturated solution at 20°C, the mass fraction of solute is 26.5% the solute mass fraction is () A.26.5% B.>26.5% C.
- 14. The mass fraction of solute in the saturated solution will decrease after the crystal is precipitated without evaporation of solvent. The mass fraction of solute in the saturated solution decreases with the precipitation of crystals without evaporation of solvent. Is that right? Why? But solute mass fraction = m solute/m solution Since the solute mass is reduced and the solution mass is reduced, how do we compare? The mass fraction of solute in saturated solution must be reduced after the crystal is precipitated without evaporation of solvent. The mass fraction of solute in the saturated solution decreases with the precipitation of crystals without evaporation of solvent. Is that right? Why? But solute mass fraction = m solute/m solution Since the solute mass is reduced and the solution mass is reduced, how do we compare?
- 15. Saturated solution at a certain temperature. The remaining solution is precipitated by solute crystal after evaporation of part of water at a constant temperature Saturated solution at a certain temperature. The remaining solution is precipitated by solute the water at a constant temperature
- 16. The mass fraction of potassium nitrate saturated solution is changed by a, increasing temperature b, decreasing temperature c, adding solute d at constant temperature and evaporating solvent at constant temperature Why not d?
- 17. T°C is the solution of KNO3(potassium nitrate). When A g of water is evaporated at constant temperature, a g of crystal is precipitated; To re-evaporate A g of water and precipitate b g of crystal (a not equal to b), answer the following questions: (1) The size of a and b. (2) What is the solubility of potassium nitrate at T°C? T°C is the solution of KNO3(potassium nitrate). When A g of water is evaporated at constant temperature, a g of crystal is precipitated; To re-evaporate A g of water and precipitate b g of crystal (a is not equal to b), answer the following questions: (1) Size of a and b. (2) What is the solubility of potassium nitrate at T°C?
- 18. A solution of substance A was evaporated to 20 g of water at a constant temperature to precipitate 2 g of crystal A. (1) At t°C, the solution of substance A evaporates 20 g of water at a constant temperature, precipitates 2 g of crystal A, and evaporates 20 g of water again at a second time at a constant temperature resulting in the precipitation of 8 g of crystal A, and the solubility of substance A at t°C. (2) To obtain crystals from lime water, the () method is usually used because () A solution of substance A was evaporated to 20 g of water at a constant temperature to precipitate 2 g of crystal A. (1) At t°C, the solution of substance A evaporates 20 g of water at a constant temperature, precipitates 2 g of crystal A, and evaporates 20 g of water at a second time at a constant temperature, resulting in the precipitation of 8 g of crystal A, and the solubility of substance A at t°C. (2) To obtain crystals from lime water, the () method is usually used because ()
- 19. At t.degree. C.,500 g of potassium nitrate solution,40 g of water evaporated,20 g of crystals precipitated, and 40 g of crystals precipitated after further evaporation of 40 g of water How much is the solubility at this temperature?
- 20. Why does the solubility of a gas solid vary with temperature, since it diffuses uniformly in molecular or ionic form after dissolution? Should we consider micro rather than macro at this point? Why does the solubility of a gas solid vary with temperature, since it diffuses uniformly in molecular or ionic form after dissolution? Should microcosmic, not macrocosmic, be considered at this point?