Factors Affecting Solubility
Objective: Identify the factors that affect the solubility of solids and gases in liquids.
Safety: Fire hazard, take care with hot liquids.
Introduction
Solubility is defined as the ability of a substance to dissolve in another substance. Solutions are mixtures containing a solute (substance being dissolved) and a solvent (substance that does the dissolving). Solutes and solvents can be solids, liquids and/or gases. True solutions are transparent. You can probably think
of many solutions that you encounter regularly such as gator-aid, soda, carbonated water or salt water.
There are several factors called variables that affect the solubility of a solute in a solvent. In this experiment you will examine three of these factors; temperature, solute size or surface area, and stirring or agitation. Some results may be obvious while others may surprise you. As you examine the factors you will
attempt to quantify the results of the experiment
Materials:
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Test tube rack with test tubes
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Test tube holder
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Ring stand with iron ring and wire gauze
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Balance
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Thermometer
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Weighing paper for each sample
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3 beakers (600mL, 400mL , 250mL)
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NaCl crystals (fine, normal, large)
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3 stirring rods
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Soda
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Bunsen burner
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Distilled water
Part I Procedure
1. Set up your ring stand with a ring and wire
gauze and Bunsen burner for heating.
2. Add 200 mL of tap water into the 250 mL beaker and heat to 70oC, then shut off the Bunsen burner.
3. Fill the 400 mL beaker to the same level as the water in the 250 mL beaker and add ice to cool.
4. Fill the 600 mL beaker to the same level as the water in the 250mL beaker, leave water at room temp.
5. Weigh 3—1 gram samples of Normal size NaCl crystals. (weigh in on waxed paper)
6. Into 3 test tubes measure and pour 20 mL of distilled water.
7. Take the temperature of the hot , cold and room temperature water and record in your
data table.
8. Place 1 test tube into each of the 3 temperature beakers, allow the test tube to sit in
the beaker for 2 minutes to come to temperature before adding the salt.
9. Pour 1 gram of NaCl into each of the 3 test tubes.
10. Insert a stirring rod into each test tube and swirl/stir the test tubes until the NaCl dissolves.
11. Record the amount of time required to dissolve the NaCl. ( look at the bottom of the test tube to see if crystals are
dissolved)
12. Dispose of all solutions in the sink.
13. Clean the beaker. Clean and rinse the stirring rods and test tubes for part 2.
Part II
1. Obtain 1 grams samples of NaCl in 3 particle sizes: Fine, Normal, Large.
2. Into 3 test tubes measure and pour 20 mL of distilled water.
3. Place a 1 gram sample of each salt into a test tube.
4. Insert a stirring rod into each sample and swirl/stir.
5. Record the time required to dissolve each salt.
6. Dispose of all solutions down the drain, rinse and clean the test tubes.
Part III
1. Obtain 2—1 gram samples of fine crystals of NaCl.
2. Into two test tubes measure an pout 20mL of distilled water.
3. Place a 1 grams sample into each test tube.
4. Insert a stirring rod into 1 test tube and swirl/stir until dissolved, record the time to dissolve the salt.
5. In the second test tube allow the salt to sit undisturbed until dissolved. Record the time to dissolve.
6. Dispose of all solutions down the drain, rinse and clean the test tubes.
Part IV
1. Observe a bottle of soda before it is opened and after it is opened. Record your observations.
2. Into 3 test tubes measure and pour a 20 mL sample of soda.
3. Use the first test tube for comparison.
4. The second test tube, place your finger/thumb over the mouth of the test tube and shake it. Be
careful when releasing the pressure, don’t get wet. Observe the test tube once shaken, record
the size and amount of bubbles after shaking.
5. Light a Bunsen burner, use the test tube holder and gently heat the soda in the test tube. Observe
and record the amount and size of bubbles after heating.
6. Dispose of all solutions down the drain. Clean all materials thoroughly and put away.
Post lab Information
All molecules are in constant motion. As the particles of solvent and solute come into contact with each other
if the solute is attracted to the solvent, the solute becomes surrounded by solvent molecules and slowly broken apart
and dissolves. The more often the solute and solvent come into contact the faster the solute will dissolve. When gases
dissolve into liquids, the normal motion of the gas molecules is restricted. For this reason the factors that increase the
solubility of solids in liquids have the opposite effect on gases dissolving in liquids.