University:
High School
Course:
High School Chemistry
Academic year:

2022
Views:

109

Pages:

2
Author:

McGowanfgu

Name:_____________________ Per:______ Worksheet: Solubility of Salt Pre-Lab Questions: (answer after reading Background Info, purpose, procedure on lab) 1. When making hot chocolate, how does stirring affect the rate of dissolving? Why? 2. How is the solubility of sugar in water affected by increasing the temperature? 3. What is the difference between a saturated and an unsaturated solution? 4. You dissolved enough sugar in water to reach its saturation point @ 80°C. What will you see begin to happen as the solution cools down? Why? 5. a. In the lab why are we heating up KNO3 in a hot water bath? b. When do we stop heating it? 6. a. After heating the KNO3 solution, why do we cool it off- what are we looking for? b. Why do we need a thermometer in the KNO3 solution- What are we measuring? Data/ Observations: (gather data from other groups as needed) Test Tube # Grams of KNO3/ mL of H2O 1 0.40 g/ 1.00 mL 2 0.60 g/ 1.00 3 0.80 g/ 1.00 4 1.00 g/ 1.00 Calculations/ Analysis: 1. Plot your experimental data on the graph (to right). Draw your best fitting curve through your data points. 2. Using your graph, how many grams of KNO3 can be dissolved in 1.00 mL of water at the following temperatures? a. 30 °C b. 40 °C c. 60 °C d. 70 °C 3. According to your graph, how does the solubility of KNO3 change as the temperature rises? 4. Using your graph, how much KNO3 must be added to make a saturated solution at 55 ºC? Crystallization Temperature (°C) Questions for Discussion Use the solubility curve provided on the right to determine the answers to the following questions: 1. Why do you think the temperatures on the graph only go from 0º C to 100º C? 2. How many grams of solute are required to saturate 100 g of water in each of the following solutions? (FYI: 100 g H2O = 100 mL) a. KClO3 at 90ºC b. NaNO3 at 10ºC 3. Which substance is most soluble at 20º Cº? 4. Which substance’s solubility changes the most from 0º C to 100º C ? 5. At what temperature does KI have a solubility of 150 g/ 100 mL water? 6. How does the solubility of the “gases” (NH3, and Ce2(SO4)3) in this graph change with increased temperatures? Can you think of a reason why this might be so? 7. NOT related to the graph: The solubility of sucrose (table sugar) in water is 200 g sucrose/ 100 mL H 2O @ 25°C. How many grams of sugar would you be able to dissolve if you halfed H2O to 50 mL of H2O @ 25°C?