Grade 8 Science and Engineering/Enriched Science and Engineering 8 Mr. Cooper/Mrs. Bellitti/Mrs. Malinauskas Name: _________________________ Period: ______ Date: __________ Notes: Analyzing and Understanding Solubility Curves The graph below is known as a solubility curve and can be used to determine how much of the solute is dissolved under certain conditions. 1. Whenever you are given a graph to analyze the first thing you should do is look at each axis to determine what information the graph is showing. In this case, what is on each axis? X‐ axis: ___________________________________________________________________ Y‐axis: ___________________________________________________________________ 2. Using your knowledge of the axes, explain what the lines of this graph are showing. _______________________________________________________________
_______________________________________________________________ Directions: Let’s practice reading one of these graphs! Use the graph to answer the following questions. REMEMBER UNITS! 3. How much sugar dissolves in 100 mL of water at 20°C? ________________ 4. How much salt dissolves in 100 mL of water at 20°C? ________________ 5. How much sugar dissolves in 100 mL of water at 80°C? ________________ 6. How much salt dissolves in 100 mL of water at 80°C? ________________ 7. How much sugar dissolves in 100 mL of water at 50°C? ________________ 8. How much salt dissolves in 100 mL of water at 50°C? ________________ 9. Which of the above substances is most soluble in water at 40°C? How can you tell? _______________________________________________________________
_______________________________________________________________ 10. Does temperature affect the dissolving of sugar and salt the same way? Explain why or why not AND use evidence from the graph to support your answer. _______________________________________________________________
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_______________________________________________________________ Grade 8 Science and Engineering/Enriched Science and Engineering 8 Mr. Cooper/Mrs. Bellitti/Mrs. Malinauskas Directions: Let’s practice look at a more complicated graph! Use the graph to answer the following questions. REMEMBER UNITS! 11. What mass of solute will dissolve in 100mL of water at the following temperatures? a. KNO3 at 70°C = ____________ B. NaCl at 100°C= ____________ c. NH4Cl at 90°C= ____________ d. Which of the above three substances is most soluble in water at 15°C. _________ 12. Use the graph to answer the following questions: a. Which compound is most soluble at 20ºC? ___________________________________ b. Which compound is least soluble at 40ºC? ___________________________________ 13. For most substances, solubility increases as temperature increases. Can you find any exceptions on the graph? Find the exceptions to this and EXPLAIN how you know they are exceptions to this rule: _______________________________________________________________
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_______________________________________________________________ 14. Which of the above substances is least affected by temperature? How can you tell? _______________________________________________________________
_______________________________________________________________ Types of Solutions: ● On a solubility curve, the lines indicate the maximum amount of solute that will dissolve at that specific temperature. This is called a _______________________________________. ● Therefore, below the line, the solution is ________________________________________. This means that it is possible to dissolve more solute at that same temperature. ● This also means that above the line, the solution is ________________________________ (if all the solute is completely dissolved). Grade 8 Science and Engineering/Enriched Science and Engineering 8 Mr. Cooper/Mrs. Bellitti/Mrs. Malinauskas 15. Label the following solutions as saturated, unsaturated, or supersaturated. If unsaturated, write how much more solute can be dissolved in the solution. Solution (in 100mL of H2O) Saturated, Unsaturated, or Supersaturated? If unsaturated: How approximately much more solute can dissolve in the solution? a solution that contains 70g of NaNO3 at 30°C a solution that contains 40g of NH4Cl at 25°C a solution that contains 20g of KClO3 at 40°C a solution that contains 70g of KI at 0°C 16. A mass of 80 g of KNO3 is dissolved in 100 g of water at 50 ºC. The solution is heated to 70ºC. How many more grams of potassium nitrate must be added to make the solution saturated? Explain your reasoning. _______________________________________________________________
_______________________________________________________________ 17. Potassium chloride is a salt substitute sold in grocery stores for people who should limit their intake of table salt (sodium chloride). Use the data table to plot the solubility curve for potassium chloride on the graph below and answer the following questions. Grade 8 Science and Engineering/Enriched Science and Engineering 8 Mr. Cooper/Mrs. Bellitti/Mrs. Malinauskas 18. At what temperature would you say that the solubility of sodium chloride and potassium chloride are about the same? How can you tell? _______________________________________________________________
_______________________________________________________________ 19. Write TWO generalizations about the solubility of the 3 substances on the graph above. _______________________________________________________________
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