Answer Key__
Name: __
Pretest: ______/36
Posttest: _______/36
Solubility and Concentration Pretest
I
1. ___ ___ a measure of how well one
substance dissolves in another
A. alloy
B. concentration
2. ___
C. heterogeneous
D. homogeneous
G___ something that has partially charged
molecules; will dissolve in water
K___ a liquid into which things are dissolved
3. ___
B___ the exact amount of solute dissolved
4. ___
E. hydrogen bond
F. nonpolar compound
in a given solvent
G. polar compound
H. saturated
spread out
I. solubility
J. solute
that temperature
K. solvent
L. supersaturated
C___ a mixture where things are not evenly
5. ___
H__ a solution that is holding all it can at
6. ___
E___ forms between the hydrogen of one
7. __
M. unsaturated
water molecule and the oxygen
of another because of their partial charges
M___ a solution that can hold more solute at that temperature
8. ___
J___ substance dissolved in a liquid to make a solution
9. ___
F___ has no partial charges; will not dissolve in water
10. ___
A___ mixture of two or more metals, e.g. brass
11. ___
L___ a solution that holds more solute than it usually can at a given
12. ___
temperature
D___ a mixture where the particles are evenly spread out; a solution
13. __
14. – 15. 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)
16. I add some more sugar to the Kool Aid from 14. – 15. and it dissolves. Was the
original liquid saturated, unsaturated or supersaturated? Explain.
Unsaturated…it was holding less so it
dissolved.
17. – 18. 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 # 19 – 23.
~52 g_ How many grams of
19. _
NH3 are needed to make a saturated
solution in 100 g of water at 20 °C?
unsaturated_ In terms of
20. _
saturation, how would you classify a
NaNO3 solution with a concentration of
90 g / 100 g of water at 50 °C?
supersaturated_ If we
21. _
lowered the temperature to 10 °C, what
would its saturation be?
~78 oC_ At what
22. __
temperature is the solubility of NaCl
the same as that of KClO3?
NaNO3_ Which is more
23. _
soluble in water, NaCl or NaNO3? How
can you tell?
NaCl is lower and flatter, which means less
dissolves and it the amount doesn’t change
much.
24. – 25. 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
26. 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?
27. Stirring/shaking?
Moves around, more interactions
between molecules
28. Breaking it into smaller pieces?
Increases surface area for interactions to
take place
29. Heating the solvent?
Moves molecules faster  more
interactions
30. – 31. Draw a water molecule. Explain why water is a polar molecule using your
drawing.
Shares electrons unevenly
Has partial charges
32. 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!
33. Describe how/why “like dissolves like.”
Partial charges in polar molecules help pull
apart the partial charges from other
polar molecules.
.0241 g/ml_ What is the concentration of 42.1 grams of silver nitrate
34. _
that dissolves in 1750 mL of water?
Conc = g solute/ ml solvent
42.1 / 1750 = .024057142
1000 g__ How many grams of salt will dissolve in 350 mL of water is
35. _
the solubility of salt is 359 g / 100 mL of H2O?
Conc = g solute/ ml solvent
359
=
x
1256.5
100
350
36. __
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