Name: ___________________________________ Period: _____ Date: ____________________
Solubility and Concentration Pretest
1. I mix up a solution of some Kool Aid by using the mix, sugar and water. What is the solute
and what is the solvent?
2. Define these terms:
Saturated:
Unsaturated:
Supersaturated:
3. I add some more sugar to the Kool Aid from #1 and it dissolves. Which of the above three
terms best describes the solution? Explain.
4. ________________ How many grams of
KBr are needed to make a saturated
solution in 100 g of water at 30 °C?
5. ________________ In terms of
saturation, how would you classify a KBr
solution with a concentration of 90 g /
100 g of water at 50 °C?
6. _________________ If we raised the
temperature to 100 °C, what would its
saturation be?
7. _________________ At what
temperature is the solubility of KBr the
same as that of KNO3?
8. _________________ Which is more soluble in water, NaClO3 or KBr? How can you tell?
9. As you raise the temperature of a solvent, how does the solubility of a solute change if it is a
a. a solid or liquid? Explain why.
b. a gas? Explain why.
10. Are any of the substances gases? Explain.
Describe how each of the following affects the process of dissolving at the molecular level.
11. Stirring/shaking?
12. Breaking it into smaller pieces?
13. Heating the solvent?
14. Why is water a polar molecule?
15. Describe how/why “like dissolves like.”
16. ____________________ What is the concentration of 42.1 grams of silver nitrate that
dissolves in 1750 mL of water?
17. ____________________ How many grams of salt will dissolve in 350 mL of water is
the solubility of salt is 359 g / 100 mL of H2O?
18.
____________________ If the solubility of KNO3 is 180 g / 100 mL of H2O, will 560 g
dissolve in 400 mL of H2O? Explain your answer in the space
below.
Name: ___________________________________ Period: _____ Date: ____________________
Solubility and Concentration Pretest
1. I mix up a solution of some Kool Aid by using the mix, sugar and water. What is the solute
and what is the solvent?
Solute: Kool Aid, sugar (what gets mixed)
Solvent: water (what it’s mixed into)
2. Define these terms:
Saturated: solvent holds as much solute as it can at that temperature
Unsaturated: solvent holds less than the maxiumum solute it can at that
temperature
Supersaturated: solvent holds more than the maxiumum solute it can at that
temperature
3. I add some more sugar to the Kool Aid from #1 and it dissolves. Which of the above three
terms best describes the solution? Explain.
Unsaturated…it was holding less so it dissolved. If it was saturated or
supersaturated, it would fall to the bottom and not dissolve.
4. ~72 grams How many grams of KBr are
needed to make a saturated solution in
100 g of water at 30 °C?
5. supersaturated if all dissolved In
terms of saturation, how would you
classify a KBr solution with a
concentration of 90 g / 100 g of water at
50 °C?
6. unsaturated If we raised the
temperature to 100 °C, what would its
saturation be?
7. ~48°C At what
temperature is the solubility of KBr the
same as that of KNO3?
8. NaClO3 Which is more soluble in water, NaClO3 or KBr? How can you tell?
The line on the graph is higher meaning that more NaClO3 can be held in solution
at this particular temperature than KBr.
9. As you raise the temperature of a solvent, how does the solubility of a solute change if it is a
a. a solid or liquid? Explain why.
Increases. Increased temperature weakens the bonds in solids and liquids and
therefore they are more easily attracted to water.
b. a gas? Explain why.
Decreases. As the molecules of both move faster, gases are forced out of
solution.
10. Are any of the substances gases? Explain.
No. All increase solubility with temperature.
Describe how each of the following affects the process of dissolving at the molecular level.
11. Stirring/shaking?
Exposes more solute to solvent.
12. Breaking it into smaller pieces?
Increases surface area for interactions to take place.
13. Heating the solvent?
Moves molecules faster = more interaction between solute and solvent.
14. Why is water a polar molecule?
Shares electrons unevenly which results in a positive end and a negative end.
15. Describe how/why “like dissolves like.”
Positive and negative charges in polar molecules will act like magnets and help to
pull apart other charged polar molecules. Since nonpolar molecules do not have
charged ends, they are not dissolved by polar molecules.
16. 0.0241 g/mL What is the concentration of 42.1 grams of silver nitrate that dissolves in
1750 mL of water?
42.1 g / 1750 mL = .024057142 g/mL
17. 1300 grams How many grams of salt will dissolve in 350 mL of water is the solubility of salt
is 359 g / 100.0 mL of H2O?
359
100
=
x_
350
x =1256.5 g
yes If the solubility of KNO3 is 180 g / 100 mL of H2O, will 560 g dissolve in 400 mL of H2O?
That concentration is less than its solubility, so yes. Solubility is the maximum amount
that can dissolve: 180 g / 100 mL = 1.8 g/mL. In this particular solution: 560 g / 400
18.
mL = 1.4 g/mL which is less than the maximum amount that can be held, so it will all
dissolve.