12 Solubility of Calcium Hydroxide PDF

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Isabelle Brown CHE113-006 Augustine Yusuf Warren Van Nort September 26, 2021

Determine and Compare the Freezing Point Depression of Water with Salt and Sugar Solutions

Introduction:

The purpose of this lab is to determine the freezing point depression of water, observe the relationship between freezing point and the sugar concentration, and to compare the freezing points of sugar and salt solutions of the same

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concentration (French, et al. 69). Colligative properties, which are properties that depend on how many dissolved particles are in a solution, will be important in this experiment. Two colligative properties used in this lab are boiling point and freezing point. When the concentration of particles in a solution is increased, the freezing

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point will decrease while the boiling point will increase (French, et al. 70). This means that there is a direct relationship between the number of particles in solution and the deviation from the normal boiling and freezing points. The equation below is used to represent freezing point depression: ΔT = iKfm

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In the equation, ΔT represents the change in temperature from the original freezing point, i is the van’t Hoff factor, Kf is the freezing point depression constant for the solvent, and m is the solution's molality (French, et al. 70). To find molality, divide the number of moles of the solute

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by kg of solvent. The solvent's mass is not temperature dependent, so this experiment uses molality instead of molarity. The following equation is used to calculate the molality of a solution: m= (mol of solute)/(kg solvent) i, the van't Hoff factor, will change depending on

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the solution. Since NaCl is an electrolyte, its i value will be 2. The sugar solution is a nonelectrolyte, so its i value is only 1. The van't Hoff factor will have a direct relationship with the freezing point depression. The freezing point depression constant of water is what needs to be

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found. This will be determined by gathering data on the freezing point of several sugar and water solutions. The sugar solutions will then be compared to a sodium chloride solution on account of the effect of the van't Hoff factor The purpose of this lab is to determine the freezing point depression of water, observe the

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relationship between freezing point and the sugar concentration, and to compare the freezing points of sugar and salt solutions of the same concentration (French, et al. 69). Colligative properties, which are properties that depend on how many dissolved particles are in a solution, will be important in this experiment. Two colligative properties

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used in this lab are boiling point and freezing point. When the concentration of particles in a solution is increased, the freezing point will decrease while the boiling point will increase (French, et al. 70). This means that there is a direct relationship between the number of particles in solution and the deviation from the

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normal boiling and freezing points. The equation below is used to represent freezing point depression: ΔT = iKfm In the equation, ΔT represents the change in temperature from the original freezing point, i is the van’t Hoff factor, Kf is the freezing point depression constant for the solvent, and m is the

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solution's molality (French, et al. 70). To find molality, divide the number of moles of the solute by kg of solvent. The solvent's mass is not temperature dependent, so this experiment uses molality instead of molarity. The following equation is used to calculate the molality of a solution:

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m= (mol of solute)/(kg solvent) i, the van't Hoff factor, will change depending on the solution. Since NaCl is an electrolyte, its i value will be 2. The sugar solution is a nonelectrolyte, so its i value is only 1. The van't Hoff factor will have a direct relationship with the freezing point

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depression. The freezing point depression constant of water is what needs to be found. This will be determined by gathering data on the freezing point of several sugar and water solutions. The sugar solutions will then be compared to a sodium chloride solution on account of the effect of the van't Hoff factor

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The purpose of this lab is to determine the freezing point depression of water, observe the relationship between freezing point and the sugar concentration, and to compare the freezing points of sugar and salt solutions of the same concentration (French, et al. 69). Colligative properties, which are properties that depend

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on how many dissolved particles are in a solution, will be important in this experiment. Two colligative properties used in this lab are boiling point and freezing point. When the concentration of particles in a solution is increased, the freezing point will decrease while the boiling point will increase (French, et al.

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70). This means that there is a direct relationship between the number of particles in solution and the deviation from the normal boiling and freezing points. The equation below is used to represent freezing point depression: ΔT = iKfm In the equation, ΔT represents the change in temperature from the

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original freezing point, i is the van’t Hoff factor, Kf is the freezing point depression constant for the solvent, and m is the solution's molality (French, et al. 70). To find molality, divide the number of moles of the solute by kg of solvent. The solvent's mass is not temperature dependent, so this experiment uses

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molality instead of molarity. The following equation is used to calculate the molality of a solution: m= (mol of solute)/(kg solvent) i, the van't Hoff factor, will change depending on the solution. Since NaCl is an electrolyte, its i value will be 2. The sugar solution is a nonelectrolyte, so its i

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value is only 1. The van't Hoff factor will have a direct relationship with the freezing point depression. The freezing point depression constant of water is what needs to be found. This will be determined by gathering data on the freezing point of several sugar and water solutions. The

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sugar solutions will then be compared to a sodium chloride solution on account of the effect of the van't Hoff factor The purpose of this lab is to determine the freezing point depression of water, observe the relationship between freezing point and the sugar concentration, and to compare the freezing

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points of sugar and salt solutions of the same concentration (French, et al. 69). Colligative properties, which are properties that depend on how many dissolved particles are in a solution, will be important in this experiment. Two colligative properties used in this lab are boiling point and freezing point. When the concentration of

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particles in a solution is increased, the freezing point will decrease while the boiling point will increase (French, et al. 70). This means that there is a direct relationship between the number of particles in solution and the deviation from the normal boiling and freezing points. The equation below is used to represent freezing point

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depression: ΔT = iKfm In the equation, ΔT represents the change in temperature from the original freezing point, i is the van’t Hoff factor, Kf is the freezing point depression constant for the solvent, and m is the solution's molality (French, et al. 70). To find molality, divide the

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number of moles of the solute by kg of solvent. The solvent's mass is not temperature dependent, so this experiment uses molality instead of molarity. The following equation is used to calculate the molality of a solution: m= (mol of solute)/(kg solvent)

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i, the van't Hoff factor, will change depending on the solution. Since NaCl is an electrolyte, its i value will be 2. The sugar solution is a nonelectrolyte, so its i value is only 1. The van't Hoff factor will have a direct relationship with the freezing point depression. The freezing point

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depression constant of water is what needs to be found. This will be determined by gathering data on the freezing point of several sugar and water solutions. The sugar solutions will then be compared to a sodium chloride solution on account of the effect of the van't Hoff factor The purpose of this lab is to determine the freezing point depression of water using a temperature time graph, determine the relationship between freezing point and the sugar concentration, and lastly to compare the freezing points of a sugar and salt solution of the same concentration (French et. al. 65). There are relationships and factors that need to be considered

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when analyzing the results of this experiment. The first is the solutions colligative properties, the boiling point and freezing point, these are properties that depend on how many dissolved particles are in a solution. When the concentration of particles in a solution is recognized to increased, the freezing point will decrease, this is an inverse relationship. However, the boiling point will increase as the concentration of particles in a solution increase and is identified to have a direct relationship (French et. al. 66). The equation below is the relationship for freezing point used to represent freezing point depression: ΔT = iKfm where ΔT represents the change in temperature from the original freezing point, i, is the Van’t Hoff factor, Kf is the freezing point depression constant for the solvent, and m is the solution's molality (French et al. 66). The Van’t Hoff factor, i, is dependent on the solution and its contents. For the purpose of this lab the Van’t Hoff factor will have a direct relationship with the freezing point depression. Molality is determined by the number of moles of the solute divided by the mass of the solvent in kilograms (French et al. 66). After all the freezing point depression of water will be compared to the sugar solutions, and then that of the sugar solution will be compared to that of the salt solution with the same concentration to determine the effect of the Van’t Hoff factor. In order to freeze the previously mentioned solutions rather quickly, a dry ice bath will be prepared. The hypothesis is that the freezing depression point of the comparable sugar solution will be greater than that of the salt solution. The experiment will in theory support the hypothesis because the Van’t Hoff factor is a

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dependent variable and is greater for the salt solution. resulting in a much lower freezing depression point. Methods: Materials (French et al. 68) 

salt (NaCl)

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sucrose (table sugar, C12H22O11)

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250 mL Erlenmeyer flask

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400mL Beaker

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50mL Beaker

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MeasureNet temperature probe

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6″ test tubes

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Dry Ice

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Analytical Balance

Procedure 1. Measure 5mL of water into 6 test tubes, leave test tube #1 to remain as pure water 2. Record the mass of the weigh boat and approximately 1g, 3g, 5g, and 8g of sugar 3. Repeat step #2 with approximately 1g of salt 4. Add 1g of sugar to test tube #2 5. Add 3g of sugar to test tube #3 6. Add 5g of sugar to test tube #4 7. Add 8g of sugar to test tube #5

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8. Add 1g of salt to test tube #6 9. Prepare Ice bath with 150mL of dry ice pellets into a 400mL beaker. Use tongs to retrieve the dry ice 10. Prepare 50g of rock salt in 200mL of pure water 11. Pour the rock salt solution over the dry ice in the beaker until the temperature becomes constant around –18°C. Add more dry ice as needed. 12. Calibrate the MeasureNet probe and temperature vs. time graph 13. Gather test tube #1, insert MeasureNet probe, “Start” data collection and insert probe and tube into the ice bath. Stir Continuously. 14. “Stop” data collection after 100 seconds and save file as “001”. Rinse and remove probe. 15. Repeat steps #12-14 with test tube #2, save file as “002” 16. Repeat steps #12-14 with test tube #3, save file as “003” 17. Repeat steps #12-14 with test tube #4, save file as “004” 18. Repeat steps #12-14 with test tube #5, save file as “005” 19. Repeat steps #12-14 with test tube #6, save file as “006” 20. Clean and dispose of all solutions and equipment. Discussion: The purpose of this lab is to determine the freezing point depression of water using a temperature time graph, determine the relationship between freezing point and the sugar concentration, and lastly to compare the freezing points of a sugar and salt solution of the same concentration (French et. al. 65). It was hypothesized that the salt solution would have a lower freezing point due to its Van’t Hoff factor. The results found the average freezing depression

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constant for all four sugar solutions to be 1.7°C/m. The resulted average freezing depression constant for all four sugar solutions on the graphs data was 2.8°C/m. Therefore, the precent error in the results based on the graph was 50.5%. Using the graphical data, and the concentration of the salt solution it was found that the theoretical freezing point of the salt solution is -1.9°C. The results then support the purpose and the hypothesis, for all freezing point depression constants were calculated and the salt solution found to have a much lower freezing point than the comparable sugar solution. The Van’t Hoff factor is the cause of this difference because the salt solution is an electrolyte and has an i value of 2. This experiment has potential sources of error that would affect the data collected and calculated. The first potential source of error is in collecting the proper amount of solute for each solution. It was difficult to gather the exact amount needed due to having to subtract the mass of the weigh boat. The second potential source of error is in measuring the mass of the solutions rather than simply the volume. The volume is needed in order to calculate the molarity and concentration accurately. Without measuring the exact volume rather than just approximately 25mL of solvent will result in a larger precent error. The third potential source of error is in using the same MeasureNet probe for each trial. The probe was exposed to a very cold temperature for 100 seconds each time and was only given a short amount of time to be cleaned to the best ability and brought back down to the initial temperature of the new solution. This error would have resulted in the miscalculation of the change in temperature and freezing point depression constant.

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Conclusion: In this lab experiment I have learned how to find the freezing point of pure water, a sugar solution, and a salt solution, using a graph and calculations. After comparing all the freezing points, I have learned the relationship between solute concentration and freezing point. These lessons are helpful in real life applications when dealing with extreme weathers and dangerous ice condition, as well as knowing how to slow down the freezing rate of a solution I wish to keep from a solid state or vice versa; speed up. I can now do this if given a graph or numerical data to calculate.

Work Cited: French, April, Allison Sault, Stephen Testa, Pauline Statman, M. Moral Savas, Francois Brotha, Carolyn Brock, Charles Griffith, Darla Hood, Robert Kiser, Penny O’Connor, William Plucknett, Donald Sands, Diane Vance, William Wagner. “Experiment 12: Freezing Point Depression” General Chemistry Laboratory Manual, Plymouth, MI: Hayden-McNeil Publishing, (2020). p. 6568. Web. 26 September 2021. https://www3.chem21labs.com/labfiles/UKY_Exp12FPofSugarSolutions_Lab.pdf

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21. 1. Mix 50-60g of NaCl in 200mL of water. 22. 2. Put 150mL of dry ice pellets into a 400mL beaker. Use tongs to retrieve the dry ice. 23. 3. Pour the NaCl solution over the dry ice in the beaker until the temperature becomes 24. constant around – 18 to 25°C

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25. 1. Mix 50-60g of NaCl in 200mL of water. 26. 2. Put 150mL of dry ice pellets into a 400mL beaker. Use tongs to retrieve the dry ice. 27. 3. Pour the NaCl solution over the dry ice in the beaker until the temperature becomes 28. constant around – 18 to 25°C

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