Class
Date
Name
~~CT'O~
t
.~nriCh
_.
m.en.
.
t
.
.
SurfaceAreaand Speed
of Dissolving
Why does a crushed solute dissolvefasterthan a large chunk? In the following
activityyou will observe and analyzehow the surface area of a solute affectsthe
speedat whichit dissolves.
.
Look at the cube in Figure 1;the length of each side is 20 cm. The area of one
side of this cube is 400 cm2(length xwidth = 20 cm x 20 cm). Becausethere are
six sideson a cube, the surface area of the cube is 6 x 400 cm2 = 2400 cm2.
Now cut the cube into eight lO-cm cubes as in Figure 2. The area of each
side of these cubes is 10 cm x 10 cm = 100 cm2.
Multiplyby sixto getthe surfaceareaof one cube:6 x 100cm2= 600 cm2.
There are eight cubes, so the total surface area of all of the lO-cm cubes is now
600 cm2 x 8
= 4800
cm2.
Next, divide the 20-cm cube into many cubes. In your mind, cut the cube
into one thousand 2-cm cubes, as in Figure 3. The area of each side of each of
these small cubes is 2 em x 2 em = 4 cm2.The surface area of each cube is 4
cm2x 6 = 24 cm2.The surface alia of all of the2-cm cubes is 1,000x 24cm2 =
24,000cm2.
(
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Figure4
Figure3
Figure2
Figure1
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dem
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1. What would the total surface area be if our large cube were divided into 8000 cubes with each
side having a length of 1 cm?
2. What formula can you write for finding the total surface area of the divided cubes?
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3. Using the formula from question 2, find the total surface area of the following:
a
a. a 4-cm cube
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b. 8 2-cm
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cubes
c. 64 I-cm cubes
4. The large cube in Figure 4 is divided into 12 cubes on each side. Find the total surface area of
.3#
the divided cube.
Solutions 31
Date
Name
Class
+~C;T'O~
iI&
Reinforcement
-
SolubilityandConcentration
t
Directions: Usetheinformationin thetableto graphthesolubilitycurvesforbariumhydroxide,Ba(OH)2;
copper(ll)
sulfate,(uSO
4;potassium
chloride,
KCI;andsodiumnitrate,NaNO
3' Use
adifferentcolored
pencilfor
eachcompound.
"
/
Solubility ing/100 9 Water
Temperature
Compound
O.C
20.C
1.67
Ba(OH)2
CuSO.
23.10
KCI
28.0
100.C
20.94
101.40
32.0
61.8
114.0
34.2
45.8
56.3
87.6
122.0
180.0
3.89
/
73.0
NaNO,
60.C
....
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-
180
I
160
...
II>
~ 140
I
t
==
is 120
=
as 100
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80
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60
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20
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.=
40
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0
20
I
40
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60
80
J:
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co
I
100
(;"
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<V
;;
120
Temperature
.&
I
a
c:
0
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'6
co
Directions: Usetheinformationin thetableandyourgraphtoanswerthefollowingquestions.
1. At about what temperature will 100g of water dissolve equal amounts of potassium cWoride
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and barium hydroxide?
2. At
about what temperature will 37 g of both copper(II)
sulfate and potassium chloride dissolve
a
in 100g of water?
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u
3. If 100 g of sodium nitrate are dissolvedin 100g of water at 60oe,is the solution formed
saturated,unsaturated, or supersaturated?
4. If 32 g of copper (II) sulfate are dissolvedin 100 g of water at 20oe, is the solution produced
t;
saturated, unsaturated, or supersaturated?
28 Solutions
-
Date
Name
~,
Directed Reading for
Content Mastery
Class
Overview
Solutions
(~t
Directions:Usethewordslistedbelowtocompletetheparagraphs.
Somewordswillbeusedmorethanonce.
solvent
solute
increases
decreases
temperature
nonpolar
electrolyte
nonelectrolyte
higher
In a solution, the 1.
2.
polar
lower
does the dissolving and the
is the substance being dissolved. For solids dissolving in
with increased surface
liquids, the speed of dissolving 3.
area, with increased temperature, and with stirring. For gasesin liquids, the speed of
solubility4.
,I
with increased temperature but
5.
with increased
pressure.
.'
In general, polar solutes dissolvein polar solventsand do not dissolve in
t
6.
solvents. Usually,nonpolar solvents dissolve nonpolar
solutes and do not dissolve 7.
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<Ii
solutes.
Solubility is usuallyexpressed as the maximum number of grams of
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a.
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0
8.
:r
9.
that will dissolve in 100grams of solvent at a certain
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A substance that forms charged ions in solution and can conduct electricity is
called a(n) 10.
. !A(n)
11.
does not
ionize in water and cannot conduct electricity. The boiling point of a water solution
of any substance is 12.
than the boiling point of water.
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The freezing point of a water solution of any substance is 13.
a
than the freezing point of water.
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Solutions
19
Date
Name
~-=-
Directed Reading for
ContentMast€ry
Class
Sedion7 . How SolutionsForm
Sedion2 . Solubilityand
t\
Concentration
Sedion3 . Particles in Solution
Directions:Foreachof thefollowing,writetheletterof thetermorphrasethat bestcompletesthesentence.
1. In a solution of sugar and water, the water is the
a~ solvent
.
b. solute
2. In the dissolving process, negative polar ends are attracted to
polar ends.
.
a. negative
b. positive
3. Grinding a solute increases its surface area, making it dissolve more
a. slowly
b. quickly
4. A gas'ssolubilityis be§tin a liquidsolventwhen the solutionis under
pressure.
a. high
,b.
low
5. Differentsubstanceshave
solubilities.
a. different
b. the same
6. The concentration of a solution of two or more liquids is expressed as a
percentage by
a. area
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b. volume
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7. As the temperature of a liquid solventincreases,the amount of solid
solute that can be dissolved in the solvent usually
.
a. increases
b. decreases
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0
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ro
8. Lines on a graph that show how much solute a solvent can hold at a
given temperature are called
a. solution graph
b. solubility curves
9. In the ionization process, water pulls the molecules of a polar substance
apart into -
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a. crystals
b. ions
10. If a soluteis a(n)
, the solutioncan conduct electricity.
a. electrolyte
b. nonelectrolyte
11. The moreparticlesof a solutethat are addedto a solution,the
the freezingpoint of the solution.
a. lower
b. higher
t
20 Solutions
Date
Name
.
-
~
'-=-
Directed .Heading for
Content Mastery
Section4
.
Class
Dissolving
Without
Water
Directions:Determine
whethereachofthefollowingispolar,nonpolar,orboth.Writethecorrect
answerin
theblanktotheleft.
1.saladoil
2.vinegar
3. oil-based
paints
4. nail polish
5. hydrocarbons
6. vitamin C
7. f')t
8. vitamin A
9. water
10. ethanol
t
0;
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Vi
Q)
'2
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0
u
11. iodine
12. dry-cleaning solvents
Directions: Answerthefollowingquestionsonthelinesprovided.
13. What is the general rule for choosing a solvent?
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0
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14. Explain why oil molecules are not attracted to water molecules in vinegar.
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15. Name three drawbacks that many nonpolar solvents have.
a
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no
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Solutions21
.
Date
Name
.-::::;=:
Directed Heading for
Content Mastery
Class
KeyTerms
Solutions
t
Directions: Matchthetermsin Column/I withthedefinitionsin ColumnI. Writethecorrectletterin theblankat
theleft.
Column II
Column I
1. mixture
that appears to have the same
composition, color, density,and tasteand
is mixed at the atomic or molecular level
2. large molecules made of carbon and
hydrogen atoms
3. charged
atom
4. describes materials with separated
positive and negative Slreas
5. substance being dissolved
6. substance
doing the dissolving
7. describes materials that have no separated
positive and negative areas
8. the maximum
amount of a solute that can
be dissolved in a given amount of solvent
9. any substance that does not con'duct electricity
10. any substance that separates into ions or
forms ions in a water solution
11. contains more solute than a saturated
solution does at a given temperature
12. a specific solute added to a solvent in order
to lower the freezing point of the solvent
13. solution that contains all the solute it
can hold at a given temperature
14. process by which particles in crystalline
solids are separated and drawn into
solution by water molecules
a. alloy
b. concentrated
c. solution
d. solvent
e. supersaturated
solution
f. unsaturated
solution
g. dissociation
h. nonelectrolyte
i. solubility
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.
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.
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u
k. antifreeze
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1. ionization
m. hydrocarbons
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n. solute
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o. dilute
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p. nonpolar
c
<l)
CD
q. polar
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a.
0
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15. process by which water pulls the molecules
in polar substances apart into ions
r. saturated solution
16. any solution that can dissolve more solute
at a given temperature
s. electrolyte
22 Solutions
t
. ..'.........1
.