AP Chemistry Lab Handout 11 "Solubility"
Your
Name: ___________________________________
Lab Partners: ____________________________
Purpose: To determine the effect of temperature on
the solubility of a salt.
Materials:
medium
test tube 100 mL
beaker balance
Sodium Chloride, NaCl or
Potassium Nitrate, KNO3 water
25 mL grad. cylinder 250 mL
beaker water bath
clock
test tube clamp test tube rack
hot plate
beaker tongs
goggles
Procedure:
1. Obtain goggles and wear them for the entire lab!
2. Place 5.0 g of your salt, either NaCl or KNO3
in a medium test tube.
3. Using the graduated cylinder, add 5.0 mL of water to the test tube. Use
the "flick" technique to mix the salt and the water.
4. Place the test tube upright in the 250 mL beaker
(55-60°C water bath)
or in a test tube rack at room temperature for five
minutes.
5. Find the mass of a 100 mL beaker to the nearest
0.1 g and record it on line (a) in your data table.
6. Pour only the liquid from the test tube into the beaker. Do not
transfer any of the solid.
7. Heat the beaker on a hot plate. When all the liquid evaporates, use
beaker tongs to remove it from the heat. After
it has cooled, find its mass and record this in your data table on line (b).
8. Calculate the information on lines (c) and (d) and report your data on line
(d) on the front board.
Observations: Salt used ____________________
Temperature
used __________
Data:
|
(a) empty 100 mL beaker |
|
|
(b) 100 mL beaker after evaporation |
|
|
(c) salt dissolved in 5 mL (b) - (a) = (c) |
|
|
(d) solubility g/100 g H2O (c) · 20 = (d) |
|
Calculations:
Error
Analysis:
Conclusion:
_______________________________________________________
_________________________________________________________________
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Answer these questions within your conclusion:
1. Which salt had the greater solubility at 55-60°C
? Which salt had the
greater solubility at room temperature?
Refer to the graph in your text book for questions 2 - 4.
2. How does an increase in temperature affect the solubility of NaCl?
3. How does an increase in temperature affect the solubility of KNO3?
4. At what temperature does NaCl have the same
solubility as KNO3?