Instructor’s Copy
Lab Worksheet – Pass The Salt
Data Table 1: The Effect of Temperature On Two Different Solutes
Observations Potassium nitrate Sodium chloride ice water Not all is dissolved hot water All of solid is dissolved ice water (2 nd ) Crystals form
Situation
Most dissolved
No change
No change
Data Table 2: Factors Affecting A Gaseous Solute
Observation
Gas bubbles are visible* When bottle is opened
Test tube is shaken
Test tube is heated
More bubbles are seen
More bubbles are seen
* Make sure students know that the bubbles are visible because the solute (carbon dioxide)
are “settling out” of the solution.
Questions:
1. In a solution of salt water,
(a) what is the solute?
salt
(b) what is the solvent? water
2. Give five examples of solutions that you use on a regular basis. Identify the solute and solvent in
each of the solutions. Answers will vary.
(a) ___________________________________________________________________________
(b) ___________________________________________________________________________
(c) ___________________________________________________________________________
(d) ___________________________________________________________________________
(e) ___________________________________________________________________________
3. Why is it necessary to keep all the conditions of an experiment identical except for the factor
being studied?
The only way to attribute a difference to one factor is to vary only one factor.
4. Give two example of gases dissolved in liquids.
(a) Carbon dioxide in water

(b) Nitrogen in blood (divers) or oxygen in blood to get to cells.
5. What are the two factors affecting solubility examined in this experiment?
(a) temperature
(b) type of solute
6. Based on what you observed in this experiment, how does temperature affect the solubility of
an ionic solute in water?
Increasing the temperature allows some ionic solids to dissolve better. It did not affect
sodium chloride much.
7. Based on what you observed in this experiment, what factors favor the dissolving of gases in
liquids?
Increase pressure (it didn’t come out of solution until the bottle was opened), not shaken,
and colder temperatures.
8. In terms of molecular motion, explain the differences between the dissolving of solids in liquids
and the dissolving of gases in liquids.
Answers will vary.
9. Which solid, potassium nitrate or sodium chloride, is more soluble in water at the temperatures
given?
(a) 10 o
C sodium chloride (b) 90 o
C potassium nitrate
Synthesis
1. What effect would an increase in pressure have on the solubility of solids in liquids?
Almost no effect.
2. What effect would an increase in pressure have on the solubility of gases in liquids?
It would increase solubility.
3. The potassium nitrate solution, as you prepared it, is a saturated solution at the higher
temperature. What does this mean?
As much solid is dissolved as can be dissolved at any given temperature.
4. Many people drink both iced tea and hot tea with lemon juice and sugar to enhance the flavor.
Explain any differences in the rate of dissolving both the sugar and the lemon juice in the two
types of tea.
Answers will vary but may include: sugar will dissolve better in hot tea. Lemon juice just
mixes in, it doesn’t really dissolve.