Name
Chem1C, Fall 09, FH, Lec Exam1
_
Read questions carefully before answering. No outside paper is allowed. Use the reverse side of your answer
paper as scratch. Use the periodic table and important constants charts provided. (Total points = 71+ 22 + 1.1...
\()6
When appropriate, show your calculation with set up equation and units.
1) 250mL of a buffer of pH 12..25 was made by dissolving
If the concentration
of Na3P04
= 4.2 x 10-13)
S2 '"
c:A J..,
'--"1/'
-'b
~-
~~
"
'I.o-<j (1\. '2...:J--\)
= -
--
j
ex- [tW
(8 pts.)
1V\
?H-=:
0 '(-
-=
%
0
7
~
0,$
39 £
2) The dissociation
\ ~jc.
L+-l.
~ (.~d-)
<1. '2-j
1.-
-r-.?L
c.. -.
Z.
S-v
02-7,-
-=-
0
0:,
--\-~ .-\-A'I..\bJ
0 . '7.£1
r
S'39.
J
J""
('
fvl {;1vf~:"
\~~~!1z.~
W"
c,
e-
-H -\ (o.:y') -\- A- (os/~
¢
cp
-\-. 0'2...JI...
0.
--\- •
2~
ka. = ~. '2"'1513
x
o .':;"'39 () N'\' tJo'2...t4-PQi
z:
\q, \~ ~
¥-~= L~.l(jlA-J _
l·O2-~
~.~
~
~c-- ' .••
O.O'2-'X.-
D 2~
(,02-x) _
'X-·02y<.,
~S\,g..)'-. () = A"'f.. {) "'X..
o 09g-
s:)
~D
~.
~\..\-'
Co.~g)
_ 0,
A."f-
1
2)
10-5 at 25.0 0C ' A solution of
~\..\-
( .% ~
-
1\J~'2-'M>~';" '2SO",,~
"'1
~~'
0 '2:x..
~.
(. 4-.,0 ~~
Oy
+
"Ur'--.?J(Wvt'v..
c
constant (Ka) for an organic acid is 1.8
b-- ~OL;-..()
I-
(C~J ~1'l.1)
this organic acid is 2.0% dissociated at 25.0 oc. What was the original concentration (in
M) of the acid in the solution? (8 pts).
L..e)- 0 ~~
~
bz. -x ~
~ L0S1J) ~
~
\...~q4~~
I ~-'~
A' ~
,4
o....~J-~
-~1D
T+P04<'(~') -?- ?ci.-(c>S'Y) +
lj)o2J
) -\- ~
orN:?.MO/..\-=0-"f--23+\
~w
~I"--o...
O.Li-
2, '68 -\-
0"
) i-kY~
"-e>. LCO'Y"J ~nt<.
0 J
Lf\c....:ct]
-\-
in water.
is present in
.•
1/
- \"),
'Q. ~
£.0
and Na3P04
is 0.4 M, what mass (in gram) of Na2HP04
the solution. (Ka3
,I . ~ _
Na2HP04
o A4\
~
~?
I
<;~
--\-P~
o. aU-'-\- \
(.Q.
2..:;'
C(rvL
(~
6l;- ~
~
~ -:::
-S"
\) (vi
3·' t<
6)
6) Calculate the molar solubilty of CaF2 at 25°Cin a solution that is 0.010M in Ca(N0:3)2 .
Ksp for CaF2 = 3.9 x 10-11. Show your calculation with ICE chart.(8 pts)
¥-S,? Y
G'\Vf<M
(J _
:'\
\...Q..CNO~h.
J
''"
\
(}..J
f\,"
Jr-. ~
- '.
e:t-C~
'2o.-(NO~2~
.0\
31~ X\O' ) 'J--
19;, ry(V)l-'~
Ce-'ftvy:-(' ~ 1M S;t 1,/, ~J~ {.' .U \
(J2-':=
-t- ~
J
~
N'03
~~,&-I-€... O.A")) •
Q..
~c\JJVl'
lWj
(',.,\
'S
.r~/QyJ\;)
e.tJrf\ ·r(\.er.
C (0
;
.) -d;~./
I
(oJ<j)
Gf'z.. (5)
T
~t(as0+ ~f(~)
--=:>
e-
.01
-\- Y'-.
\'J\
-r '2'X
+.01
_ ~()\ M
oc-
'~,"
'L.?<....
7) Water (H20) and the alcohol methanol (CH30H) are infinitely soluble in each other. The
primary intermolecular force responsible for this is
7) \-\-- b oYId
vi8
(2 pts).
8 Physical properties o~a sol~tion ~t1-epend on the quanti of the solute particles
p esent~ot
the rid \~~_ntity of'th~articles, areerm~
~
Fr6pirt!>s'(
pts).
'--
8)
L.:ANtz L.l'LV
9) At 20°C, an aqueous solution that is 24.0%by mass in ammonium chloride (NH4Cl) has
9)
Lt
.·1% N\
a density of 1.0674g/mL. What is the molarity of NH4Cl in the solution?(8 pts)
,o-e fr'
1\
~
('? _
-r-.
'"
tL
'
C(5Y'-1\(J-.Jvv'-~
~\~~ or
tf- O't-- ~J.~
rnl\d
r-)
/I
~
"'1
I\. \
~
r
n
§. ''''' \ 'L-\ u-..)
./
t
Jj-
~.{}tt'
~J'f\~
,
~
~A.
o,
~N\ '
26
S
I
"'..--.
-;:. \J'(\ ~
,1) _.
I
,M
\z\ IA)
----_.
==-
3
V)
-
V.-:.
\V\. . O~ ~
- (.l
- b _.\\ 067'1 %/,«,2.) '~1..
.: \ i, b
'j
y,
(
10) The Henry's law constant for helium gas in water at 30°C is 3.70 x 10-4 M/atm. When the
partial pressure of helium above a sample of water is 0.650atm, the concentration of
helium in the water is
M. (4 pts)
S,7
?-
£-~..t~J~,Q,
~ Jr-. t'.A::::: ~-e..
Sr (.
\.( ~ \\0Nl1 s
\)
\-5 ~
rf·
f)
ro·\. . t"
?sr.,
s+er·f
. ,,,,,,, ("*
-,
'?:l·7 1- \ 0
'"
__
- It
...••
~.
r}clr. : ... "",,~/,~
1
'-
'
-\.\-
~'
~ '2. 'L\-\"'i
\ ()
I,A
11) A solution contains 3.62 mass % of NaOCl. Calculate (a) the molality (4 pts.) of NaOCl in
the solution. (4 pts.)
3 ' b 2.- VV'-dJ'()
Mo\~
1. tJ
~
iA-D d
~
IN' WJ'/\.J::,
'f'
N~d-=
\
be
G- S cJ
if- 61-Y'0~P!L
6t ~
lA..)~,
\-ev~\-1~ '3. 6 'l-~ ~1"'-00/
It' (',
11)
0 So () L\- 'M,
I
<;0 : J... 'I\V'
1 1-) -~.
-:::-.Cj 6 •3 ~
a-
iO'OU
-tv ~ '/r.
V. c.
~.6-l.~)1J"\\J\l 6]-N~)L{
~\b:~%~ +ALO /'1 ~
~,b'L'd"?&3"'\b~3S·S-)~/~
O. 0C4b3<e kg
_
6 -:::-~bl))/74'~~I~_'9Lj-~~:·9.
"Dq6~~¥.....
(b) Calculate it's the mole fraction (4 pts.)
t "...-\'
r>:
b
I'
\
f)
U .-'
t
e
'10'
- 'O~~3~-
~
'··r ~.\ '\ .
~
(.
•
.
I
/
J If.
0\\ ~.. n _
.
tv"'" -,..,,;
62..
LA) t'4PJi-
C\ 6\~ ~ ~
-\~~IYf'~IC
MULTIPLE CHOICE. Select the one alternative that best completes
the statement or answers the question (2 pts each).
12) The process of solute particles being surrounded by solvent particles is known as
A) salutation
B deh dration
\ C solvation
D) agglutination
E) agglomeration
4
_
12)
~
_,
c: :..
,,0
13) In a saturated solution of a salt in water,
_
A) seed crystal addition may cause massive crystallization
B) the rate of dissolution > the rate of crystallization
C) addition of more water causes massive crystallization
,-tlle rate of -: sfcilliZation ,; fue rate of disso ution
E) the rate of crystallization
> the rate 0 dissolution
13)
14) A supersaturated
14)
solution
'"
_,
a higher concentration than the solubility/
B) must be ~actwii:ht:mdTssolv~'solid
-C) is one that has been heated
D) exists only in theory and cannot actually be prepared
E) is one with more than one solute
--L"":'-_
nB'On;'W[th
15) Ammonium
nitrate (NH4N03)
dissolves
readily in water even though the dissolution
endothermic by 26.4 kj/mol. The solution process is spontaneous because
A) osmotic properties predict this behavior
B) of the decrease in enthalpy upon addition of the solute
C) the vapor pressure of the water decreases upon addition of the solute
D) of the increase in disorder upon dissolution of this strong electrolyte
E) of the increase in enthalpy upon dissolution of this strong electrolyte
substances
15)
_
16) An unsaturated solution is one that
_
A) contains more dissolved solute than the solubility allows
B) contains no solute
C) contains the maximum concentration of solute possible, and is in equilibrium
undissolved solute
D) has a concentration lower than the solubility
E) has no double bonds
17) Which one of the following
is
16)
D
with
17)
is more likely to dissolve in CCI4?
A)HBr
B) NaCl
C)HCl
D)CBq
E) CH3CH20H
18) Which of the following choices has the compounds
solubility in water? (least soluble -> most soluble)
A) LiF < NaN03 < CHCl3
correctly arranged
in order of increasing
18)
B) CCl4 < CHCl3 < NaN03
C) CH30H
< Cl4 < CHCl3
D) CH30H
< CH4 < LiF
E) CH4 < NaN03
19) The concentration
____
M.
A) 0.300
< CHCl3
of nitrate ion in a solution that contains 0.900 M aluminum
B) 1.80
D) 0.450
C) 2.70
5
nitrate is
E) 0.900
19)
C
_
b
20) Which of the following could be added to a solution of potassium fluoride to prepare a buffer?
A) sodium fluoride
B) hydrochloric acid
C) potassium acetate
D) sodium hydroxide
E) ammonia
20)
21) In which of the following aqueous solutions would you expect AgBr to have the lowest solubility?
A) 0.10 M AgN03
B) 0.15MKBr
C) 0.10 M LiBr
D) 0.20 M NaBr
E) pure water
21)
1>
22) The pH of a solution prepared by mixing 50.0 mL of 0.125 M KOH and 50.0 mL of 0.125 MHO is
22)
C.
A) 8.11
B) 5.78
C) 7.00
D) 0.00
E) 6.29
Answer if the statement is true or false and then briefly explain your reasoning.
23) Adding solute to a solution decreases the vapor pressure of the solution (2pts). Briefly explain why (2
pts.).
TorF
24) The extent of ionization of a weak electrolyte is increased by adding to the solution a strong electrolyte
that has an ion in common with the weak electrolyte (2pts). Briefly explain why (2 pts.) ..
T o~
.z.. (,.~)-,
6
.. 1,
25) The solubility product of a compound is numerically equal to the product of the concentration of the
ions involved in the equilibrium, each multiplied by its coefficient in the equilibrium reaction.(2pts}.
Briefly explain why (2 pts.).
~+
A7--IO'j (~
\"s" ~ \j\
Cj.\-. ", s
-\-0 -\{"..C'_
l-"
\"
. 1\.
l>M"V"'",
-----._
\Y-"')
L
~~ ?~.Jv~ ..A··
--\J"R.
~~
~
~+j")C
q- ~c....
C)',-
.
.1
. ::<;l_
t'C"Y'
-€'.()~
J7.
'1<..-
A~
~
~B
(~)
le?J 'a-
(':..Q.J/j .."'"~\..'"
~."
,> • •.. ,. l
'.
".
",.,
-n
>
•
.~\."
lj>/'"'i'"
.-
Le> ~-~
0r; r \ x.J· t-:'\
ti'\
•
26) The solubility of slightly soluble salts containing basic anions is proportional to the pH of the
solution.(2pts}. Briefly explain why (2 pts.),
.
,
\ ••,.l
...
T{0
-<'.- (0 ~,')'( .
.•..
\
(-t'-Q,·· ••1.
'/
7
To(£j