Student Portal:

Solutes and Solubility

Investigation 3 – Lab

 

 

 

 

 

 

 

MINDSET

This Investigation is designed to:

  • demonstrate to you the difference between a mixture and a solution, and
  • illustrate how the rate of solubility of a solute is changed by increasing the temperature of the solvent.

BE PREPARED

Student Preparation for the Investigation includes having students gather the following materials. This preparation takes place on lab day after student lab groups have settled at their assigned lab tables.

Note: The materials are listed in students’ SDRs. They are also listed below for your reference.

  • (1) triple beam balance
  • (2) weigh dishes
  • (2) 400 ml beakers
  • (1) glass stir rod
  • (1) lab scoop
  • (1) 100 ml graduated cylinder
  • (1) pitcher filled with cold water
  • (1) pitcher filled with hot water
  • (1) stopwatch
  • (1) thermometer
  • gloves for each student
  • goggles for each student
  • (1) calculator
  • (1) marker
  • (1) roll of masking tape.
  • According to the table below, each student group will make solutions using two of the following compounds: baking soda (NaHCO3), salt (NaCl), and sugar (C12H22O11).

Solutes 3 Lab Student Prep 1st

  • Student groups should obtain cream of tartar, baking soda, salt, and sugar in the amounts shown in the table below.

Solutes 3 Lab Student Prep 2nd

Direct one student from each lab group to collect the materials listed in their SDRs.

INVESTIGATE

  • You will be using the same compounds that were used in Investigations One and Two to test the effect of heat on the rate of solubility.
  • You will test the effect of temperature on the rate of solubility of two different solutes in the same solvent, water.
  • Be sure to reflect on the PreLab video as you move through the procedural steps.
  • During the Experiment, every procedural step is important. If one step is skipped, data can become invalid. To help you keep on track, read each step thoroughly, complete the step, then check it off (Read it – Do it – Check it).
  • Complete all of the procedural steps in your SDR.

Note: The procedural steps are listed below for your reference. The Experiment includes the following:

  1. During Trials 1 and 2, each group will test if the temperature of the mixture of the solute and the solvent affects the rate of solubility of two different solutes.
  2. Table A shows the two compounds that will be investigated by each group. Highlight or circle the compounds in Table A that your group will investigate.

Solutes 2 Lab Table A

Trial 1:

Note: The cold water should be the coldest tap water available. The hot water should be the hottest tap water available. If hot water is not available, water can be heated to 50°C using a stirrer/hot plate.

Note: Each student group will use 100 ml of water for both trials.

  1. In this Trial, you will test the effect of using cold and hot water on the rate of solubility of the first compound.
  2. Record: Write the name of the first compound circled in Table A that you will test. Student answers will vary according to their group.
  3. Use Table B to find the number of grams of the compound you should use in Trial 1. Write the mass in the middle column of Table C.

Solutes 3 Lab Table B

  1. Obtain the mass of the sample using the triple beam balance. Use Table C and refer to the Procedure, Measuring Mass Using a Weigh Dish or Beaker for help.
    1. Record: Write the mass of the weighing dish in the first column of Table C.
    2. Record: Write where the poises should be set for each mass in the last column of Table C.
  2. Pour the sample of the compound into one 400 ml beaker. Use the masking tape and the marker to label this beaker “Cold.”
  3. Use the steps above to measure the same number of grams of the compound. Pour the sample of the compound into a second 400 ml beaker. Use the masking tape and the marker to label this beaker “Hot.” Put this beaker to one side.
  4. Write the name of the compound in the first row of Table D.
  5. Use the masking tape and the marker to label one pitcher “Cold” and the other pitcher “Hot.”
  6. Use the thermometer to measure the temperature of the cold water in the pitcher labeled “Cold.” Record the temperature in the row labeled “Cold” of Table D.
  7. Use the graduated cylinder to measure 100 ml of the cold water and pour the water into the beaker labeled “Cold.”
  8. One group member should stir the contents of the beaker labeled “Cold” using the stir rod. A second group member should use the stopwatch to time the stirring. All students should observe the contents of the beaker.
  9. Start the stopwatch. After 1, 2, 3, 4, 5, and 6 minutes, observe the contents of the two beakers and decide if the compound has dissolved or not dissolved. Record your observations for each time point in Table D.
  10. Fill the pitcher labeled “Hot” with hot tap water.
  11. Use the thermometer to measure the temperature of the hot water in the pitcher. Record the temperature in the row labeled “Hot” of Table D.
  12. Use the graduated cylinder to measure 100 ml of the hot water and pour the water into the beaker labeled “Hot.”
  13. One group member should stir the contents of the beaker labeled “Hot” using the stir rod. A second group member should use the stopwatch to time the stirring. All students should observe the contents of the beaker.
  14. Start the stopwatch. After 1, 2, 3, 4, 5, and 6 minutes, observe the contents of the two beakers and decide if the compound has dissolved or not dissolved. Record your observations for each time point in Table D.
  15. Pour the contents of the beakers into the sink. Rinse the beakers and the stir rod with water.

Trial 2:

  1. In this Trial, you will test the effect of using cold and hot water on the rate of solubility of the second compound.
  2. Record: Write the name of the second compound circled in Table A you will test. Student answers will vary according to their group.
  3. Use Table B to find how many grams of the compound you should use in Trial 2. Write the amount in the middle column of Table E.
  4. Obtain the mass of the sample using the triple beam balance. Use Table E and refer to Measuring Mass Using a Weigh Dish or Beaker for help.
  5. Pour the sample of the compound into one 400 ml beaker. Use the masking tape and the marker to label this beaker “Cold.”
  6. Use the steps above to measure a second mass of the compound. Pour the sample of the compound into a second 400 ml beaker. Use the masking tape and the marker to label this beaker “Hot.” Put this beaker to one side.
  7. Write the name of the compound in the first row of Table F.
  8. Use the thermometer to measure the temperature of the cold water in the pitcher labeled “Cold.” Record the temperature in the row labeled “Cold” of Table F.
  9. Use the graduated cylinder to measure 100 ml of the cold water and pour the water into the beaker labeled “Cold.”
  10. One group member should stir the contents of the beaker labeled “Cold” using the stir rod. A second group member should use the stopwatch to time the stirring. All students should observe the contents of the beaker.
  11. Start the stopwatch. After 1, 2, 3, 4, 5, and 6 minutes, observe the contents of the two beakers and decide if the compound has dissolved or not dissolved. Record your observations for each time point in Table F.
  12. Fill the pitcher labeled “Hot” with hot tap water.
  13. Use the thermometer to measure the temperature of the hot water in the pitcher. Record the temperature in the row labeled “Hot” of Table F.
  14. Use the graduated cylinder to measure 100 ml of the hot water and pour the water into the beaker labeled “Hot.”
  15. One group member should stir the contents of the beaker labeled “Hot” using the stir rod. A second group member should use the stopwatch to time the stirring. All students should observe the contents of the beaker.
  16. Start the stopwatch. After 1, 2, 3, 4, 5, and 6 minutes, observe the contents of the two beakers and decide if the compound has dissolved or not dissolved. Record your observations for each time point in Table F.
  17. Pour the contents of the beakers into the sink. Rinse the beakers and the stir rod with water.

CLEAN UP

Clean up your bench after completing your experiments.