Solubility Practice a Curvy Subject

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KEY
Temperature ( 0 C)
Directions: Answer in complete sentences and show all work for calculations.
1. What relationship exists between solubility and temperature for most of the substances shown?
A direct relationship is shown for most substances, as temperature increases the
solubility of most substances increases.
2. What is the exception?
The exception is gas solubility. Gases are less soluble at higher temperature,
illustrating an indirect relationship
3. What explains why solids become more soluble as temperature increases and why gases become
less soluble? Use the following words to help justify your response: temperature, collisions and
energy.
As temperature increases both speed of the water molecules and the number of
collisions increase. A solid remains dissolved by the continual motion of the eater
molecules. The more energy and motion, the more particles that can remain in
solution. This is especially true for ionic compounds, because water is polar and the
opposite charges help stick the water molecules to the ions. Gases are often nonpolar
and they have very low boiling points, so as temperature increases they tend to “boil
away”. That is why a soda will go flat much faster if it is left in a warm place.
4. Which is more soluble NaNO 3 or KCl? Does the temperature matter? Why or why not?
NaNO 3 because the higher line indicates that more NaNO 3 can be dissolved at ALL
temperatures.
5. How does the line drawn for a particular substance relate to the saturation of a solution of that
substance? Use the following words to help justify your response: saturated, unsaturated,
supersaturated.
The line marks the saturation point of a solute in 100 grams of water. If you have less
grams dissolved than indicated by the line then your solution is unsaturated at that
temperature. If you have more, then your solution is supersaturated at that
temperature.
6. How many grams of NH 4 Cl will dissolve in 100. grams of water at 90. 0 C? 72 grams
7. How many grams of KClO 3 will dissolve in 300. grams of water at 30. 0 C?
300. g of H 2 O X 10. g KClO 3 = 30. g KClO 3
100. g H 2 O
8. How would you make a saturated solution of KNO 3 at 60. 0 C in 50. grams of water?
The graph indicates that that 106 grams of KNO 3 will dissolve in 100. grams of water,
so I need only 106g /2= 53 grams of KNO 3 to make the solution. So I would measure
out 50 grams of water and 53 grams of KNO 3 and mix them together to make the
solution.
9. If you were asked to make a saturated solution of KCl in 100. grams of water, what other piece of
information would you need to before you could start? Why?
You would need to know the temperature of the solution. The saturation point is very
different depending on the temperature
10. If you start with a saturated solution of NH 3 in 100. grams of water at 10. 0 C, how many grams of NH 3
gas would bubble out of solution if you raise the temperature to 80. 0 C?