PS-3.5 - Solubility of Ammonium Chloride Lab

Solubility of Ammonium Chloride
Problem: How does surface area and temperature affect solubility?
Hypothesis: _____________________________________________________________________________
__________________________________________________________________________________________
Experiment:
Independent Variable: _________________________________________________________________
Dependent Variable: ___________________________________________________________________
Controls: _______________________________________________________________________________
Safety:
1. _________________________________________________________________________________
2. _________________________________________________________________________________
Materials:
♦ 250 mL beaker
♦ Thermometer
♦ Hot plate
Experiment:
1. Put 50 mL of room temperature water into a clean beaker.
♦ Ammonium chloride
♦ Stir stick
2. Use a thermometer to measure the temperature of water. Record this temperature in your
Data Table. DO NOT LEAVE THE THERMOMETER IN THE BEAKER.
3. Add one spoonful of ammonium chloride to the water in the beaker. Stir vigorously until
no more of the solid will dissolve. Make sure you allow enough time for the solid to
dissolve. Be careful handling ammonium chloride and its solutions, which are poisonous.
4. Repeat step 3 until no more ammonium chloride will dissolve. Note the number of
spoonfuls of ammonium chloride that you added. Be sure to allow enough time for each
spoonful of ammonium chloride to dissolve before adding more. Record the number of
spoonfuls that dissolved in your data table.
5. Place the beaker of ammonium chloride solution on a hot plate. Place the thermometer in
the beaker. Turn the hot plate to the medium-low setting and warm the solution to 40°C.
6. Remove the thermometer from the beaker. Add more spoonfuls of ammonium chloride to
the beaker. Stir the solution and use the thermometer to check the temperature of the
solution after you add each spoonful. Note the total number of spoonfuls of ammonium
chloride that you added. Be sure to allow enough time for each spoonful of ammonium
chloride to dissolve before adding more. Use the heat setting of the hot plate to keep the
temperature constant as you add ammonium chloride.
7. Record the total number of spoonfuls that have dissolved.

8. Turn up the hot plate to warm the solution to 60°C. Then, repeat steps 6 and 7 with the
solution at this temperature.
9. Turn up the hot plate to warm the solution to 80°C. Then, repeat steps 6 and 7 with the
solution at this temperature.
10. When you have recorded all of your data, turn off the hot plate and allow the solution to
cool. Rinse the solutions down the drain. Let the water run continuously for about 1
minute.
11. On a sheet of paper, make a graph of the solubility of ammonium chloride versus
temperature. Plot temperature on the horizontal x-axis and solubility (in spoonfuls per 50
mL water) on the vertical axis.
Observations:
Temperature
(°C)
18-20
Number of Spoonfuls of Ammonium Chloride
Dissolved
40
60
80
Include the following questions in your discussion and don’t forget a conclusion:
1. Create a graph of the above information.
2. Predict what effect, if any, you think the size of salt grains would have on their solubility.
Explain your answer.
3. Based on your graph and your observations what do you think the solubility of ammonium
chloride (in spoonfuls per 50 mL water) would be at 10°C? At 70°C? At 100°C?