The Effect of Temperature on Solubility
PURPOSE:
To observe the effect of temperature on solubility for two different solutes, sodium chloride and
potassium nitrate.
EQUIPMENT AND MATERIALS:
beakers (2) 400 – 600 mL
solvent: distilled water (20 mL
hot plate
total)
solute 1: 10.0 g NaCl
goggles
solute 2: 10.0 g KNO3
tap water
glass stirring rod
test tube rack
tongs
test tubes (2) 18 mm x 150 mm
10mL graduated cylinder
PROCEDURES:
1. Set up equipment as shown below: FILL beakers with about 400 mL tap water
Hot water bath to heat
test tube
Cold water bath to cool
test tube
2. Put one beaker of tap water on the hot plate to start heating up for the HOT WATER
BATH (get this started because it takes a while to heat up the water)
3. Measure out 10.0 g of NaCl using a weigh boat and balance (put NaCl in a test tube)
4. Use a 10 mL graduated cylinder to measure out 10.0 mL of distilled water.
5. Add the 10 mL of distilled water to the small test tube containing NaCl.
6. Stir the solution with the glass stirring rod for several minutes until it is saturated.
7. Record your observations for “INITIAL NaCl” (make a DRAWING and write observations)
8. Put the test tube of NaCl into the HOT WATER BATH.
9. Heat the sodium chloride solution until the water is near boiling and stir the solution
10. While the NaCl is heating up in the hot water bath, measure out the 10.0 g of KNO3. Put this
into a new test tube. Add 10 mL of distilled water. Stir the solution for several minutes
until it is saturated.
11. Record your observations for “INITIAL KNO3”
12. Record your observations for NaCl in the hot water as “HEATING NaCl”.
Take the NaCl out of the hot water bath using TONGS.
Put the NaCl test tube in the beaker of cold tap water.
13. Cool the NaCl test tube in a beaker of cold tap water for 5 to 10 minutes.
14. Record your observations as “COOLING NaCl”
15. Record your observations for KNO3 in the hot water as “HEATING KNO3”.
Take the KNO3 out of the hot water bath using TONGS.
Put the KNO3 test tube in the beaker of cold tap water.
16. Cool the KNO3 test tube in a beaker of cold tap water for 5 to 10 minutes.
17. Record your observations as “COOLING KNO3”
OBSERVATION: DRAW PICTURES of what you see and WRITE OBSERVATIONS
Solute:
Observations: cooling
Observations: Initial
Observations: Heating
NaCl
KNO3
Questions & Conclusions:
1. Use the graph on the
right to estimate the
amount of NaCl that
dissolved in 10 g of
water at room
temperature. (~22ºC)
LOOK AT THE Y-axis
UNITS (HINT, HINT)
2. How much of the KNO3
dissolved at room
temperature? (See #1
for HINT and room
temp. info)
3.
How much of the NaCl
dissolved after heating
to 100ºC?
4.
How much NaCl
precipitated out of
solution when you
cooled the solution from
100ºC to ~22ºC?