Answer Key__
Name: __
Pretest: ______/33
Posttest: _______/33
Solubility and Concentration Pretest
F___ a measure of how well one
1. ___
substance dissolves in another
A. concentration
B. hydrogen bond
molecules; will dissolve in water
C. nonpolar compound
D. polar compound
D___ something that has partially charged
2. ___
H___ a liquid into which things are dissolved
3. ___
A___ the exact amount of solute dissolved
4. ___
I
5. ___ ___
E. saturated
F. solubility
in a given solvent
G. solute
H. solvent
a solution that holds more solute than
it usually can at a given temperature
I. supersaturated
J. unsaturated
E__ a solution that is holding all it can at
6. ___
that temperature
B___ forms between the hydrogen of one water molecule and the oxygen of
7. __
another because of their partial charges
J___ a solution that can hold more solute at that temperature
8. ___
G___ substance dissolved in a liquid to make a solution
9. ___
C___ has no partial charges; will not dissolve in water
10. ___
11. – 12. 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)
13. I add some more sugar to the Kool Aid from 11. – 12. and it dissolves. Was the
original liquid saturated, unsaturated or supersaturated? Explain.
Unsaturated…it was holding less so it
dissolved.
14. – 15. Describe what would’ve happened for the other two terms above.
If it was saturated, exactly the amount you
added would fall to the bottom and not
dissolve.
If it was supersaturated, more than the
amount you added would fall to the
bottom and not dissolve.
Use the graph at the right for #16 – 20.
~52 g_ How many grams of
16. _
NH3 are needed to make a saturated
solution in 100 g of water at 20 °C?
unsaturated_ In terms of
17. _
saturation, how would you classify a
NaNO3 solution with a concentration of
90 g / 100 g of water at 50 °C?
supersaturated_ If we
18. _
lowered the temperature to 10 °C, what
would its saturation be?
~78 oC_ At what
19. __
temperature is the solubility of NaCl
the same as that of KClO3?
NaNO3_ Which is more
20. _
soluble in water, NaCl or NaNO3? How
can you tell?
NaNO3 is higher which means more
dissolves.
NaCl is lower and flatter, which means less
dissolves and it the amount doesn’t change
much.
21. – 22. As you raise the temperature of a solvent, how does the solubility of a
solute change if it is a
Solid? Explain why.
Increases.
As the molecules of both move faster,
more solute can dissolve
Gas? Explain why.
Decreases.
As the molecules of both move faster,
more solute escapes the solvent
23. Are any of the substances gases? Explain.
NH3 is a gas, because the line goes down as
temp goes up. This shows less can be
dissolved at higher temps.
How do the following affect the process of dissolving, at a molecular level?
24. Stirring/shaking?
Moves dissolved away, more interactions
between molecules
25. Breaking it into smaller pieces?
Increases surface area for interactions to
take place
26. Heating the solvent?
Moves molecules faster  more
interactions
27. – 28. Draw a water molecule. Explain why water is a polar molecule using your
drawing.
Shares electrons unevenly
Has partial charges
29. Draw the hydrogen bond that occurs with water molecules.
Is between hydrogen of
one molecule and oxygen
of another.
Not between hydrogen
and oxygen of same
molecule!
30. Describe how/why “like dissolves like.”
Partial charges in polar molecules help pull
apart the partial charges from other
polar molecules.
Concentration = mass of solute / volume of solvent
.0241 g/ml_ What is the concentration of 42.1 grams of silver nitrate
31. _
that dissolves in 1750 mL of water?
Conc = g solute/ ml solvent
42.1 / 1750 = .024057142
1300 g__ How many grams of salt will dissolve in 350 mL of water is
32. _
the solubility of salt is 359 g / 100. mL of H2O?
Conc = g solute/ ml solvent
359
=
x
1256.5
100
350
33. __
yes__ If the solubility of KNO3 is 180 g / 100. mL of H2O, will 560 g
dissolve in 400 mL of H2O?
Conc = g solute/ ml solvent
That concentration is less than its solubility
560/400 = 1.4 g/ml
180/100 = 1.8 g/ml