Check your responses to the video solubility lab here. Hover over the blank columns in the table.
Data Table:
| #1 Assigned Temperature degreeC |
#2 Mass of evaporating dish + cover | #3 Mass of evaporating dish + cover + KCl solution | #4 Mass of evaporating dish + cover + dry KCl | #5 Mass of KCl (#4-#2) | #6 Mass of water (#3-#4) | Mass of KCl per 100 g of water |
|---|---|---|---|---|---|---|
| 10 | 37.81 g | 48.75 g | 40.54 g | 2.73 g | 8.21 g | 33.3 g |
| 20 | 37.65 g | 50.42 g | 40.99 g | 3.34 g | 9.43 g | 35.5 g |
| 30 | 36.95 g | 47.82 g | 39.81 g | 2.86 g | 8.01 g | 35.7 g |
| 40 | 37.80 g | 48.19 g | 40.63 g | 2.83 g | 7.56 g | 37.4 g |
| 50 | 36.50 g | 47.49 g | 39.75 g | 3.25 g | 7.74 g | 42.0 g |
| 60 | 37.75 g | 50.08 g | 41.52 g | 3.77 g | 8.56 g | 44.0 g |
| 70 | 35.98 g | 48.29 g | 39.86 g | 3.88 g | 8.43 g | 46.0 g |
| 80 | 37.81 g | 48.64 g | 41.37 g | 3.56 g | 7.27 g | 49.0 g |
| 90 | 36.99 g | 48.96 g | 40.98 g | 3.99 g | 7.98 g | 50.0 g |
Solubility Lab Graph
Check your graph by clicking here.
Conclusions:
1. The solubility of a solute is the maximum mass of the solute that will dissolve in a certain amount of water at a certain temperature.
This is the same as saying that solubility is the concentration of a saturated solution of the solute.
2. From your graph, what mass of KCl can be dissolved in 100 g of water at these temperatures?
Use dotted lines on your graph to show how you used your graph to determine your answers:
a) 25 °C ~36 grams
b) 55 °C ~42 grams
3. For each of the following, tell whether the solution would be saturated, unsaturated, or *crystallizing.
(Hint: Plot the point and see whether it lies above, below, or on the best-fit line. Remember that the line represents a saturated solution.)
a) 40.0 g of KCl in 100 g of water at 75 °C unsaturated
b) 34.0 g of KCl in 100 g of water at 55 °C unsaturated
c) 45.0 g of KCl in 100 g of water at 25 °C crystallizing
*Normally, crystallization (rather than supersaturation) occurs when more solute is present than what can be dissolved in a given amount of solvent at a given temperature. Crystallization simply refers to the excess solute “crystallizing” and settling out of the solution. Supersaturation is rare.
Video Quiz Answers:
Which gas will diffuse at a faster rate, CH4 with a molar mass of 16 g or SO2 with a molar mass of 64 g? A. CH4
Luster, malleability, and ductility are true for what type of bonding? D. metallic
Saturated solutions can be C. either concentrated or dilute.
Which of these statements about dissolving gases in liquid solvents is true? B. Increasing the pressure increases the solubility of a gas.
A solution with more solute dissolved than normally possible is said to be _____. C. supersaturated
A solution that can dissolve even more solute although a large amount has already been dissolved is _____. C. concentrated and unsaturated
Henry’s Law relates _____. A. pressure to gas solubility