CHM 1311: General Chemistry 1, Fail20A4
Exam #3. November 3. 2044
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Useful equations and constants
electron:
mass(m") = 9.1093897x 10-28g
proron:
mass= I.673 x 10-'o g
neufron:
mass= L675 x I0-'o g
_1 0
charge(e) - -1.60 x 1 0 ^ - c
1 mole= 6.A22x 1023= Avogadro'snumber
l amu= i.66054 x10-24 s.
1. (2)
)
1
()\
|
/
l
4. (2)
1
{ 1 }
6 r?')
'7 ()\
8. (10)
o ()\
DO NOT WRITEIN THESEBLANKS
10. ( 3)
1 1 .( 6 )
12. (3)
13. ( 3)
14. (4)
15. ( 3)
16. (2)
T7. ( 3)
18. ( 2)
1e.(5)
20. (4)
21. (6)
22. (4)
23. ( 3)
(3)
25. (4)
L O . (2)
27. (r2)
4,4
TOTAL (1oo)
1. (2 pts) Which one of the following basesis NOT a known strongbase?
a.
Ca(OH)z(aq)
b.
Ba(OH)2(aq)
c.
KOH (aq)
. A
o
NaOH (aq)
NH3 (aq)
2. (2 pts) How manymoiesof ionsareproducedin soiutionby dissociation
of i moleof
Nicl2.6 H2o?
a . L
( b.l3
n
A
d.6
e.9
3. (2 pts) What is the name of IIBTO2?
4. (2 pts) What is the formuia for hydroiodic acid?
5. (3 pts) The oxidationnumberof sulfurin Na2SeO1,
is
6. (3 pts) Which of the foiiowing is TRIIE?
a. oxidation is the gain of electrons
( b.) the substance
oxidizedis the reducingagent
c. oxidation is a decreasein oxrdationnumber
d. all metal cationsare poor oxidizing agents.
e. all statementsare false.
bnr},4CI.^s
ac''/
t+T
+2
7. (2 pts) In the reactionbelow, which ions are the spectatorions?
K2SO4(aq) + Ba(NO3)2(aq) )
1t
)-
a.
Ba- andSOo-
U.
Ba- andK
)
BaSOa(s) + 2 KNO3 (aq)
t
!
)t
Ba-' andNO3
A
u.
--+
, ^^ 2l( and 5u4
!
_
K andNO3
8. An unknowncompoundis composedof C, H and N. The following percent
compositionis determinedexperimentallyfor a 10.00-qramsampleof the compound:
74.07ocarbon,8.7}Vo hydrogen,and17.3Vorutrogen.
(a) (6 pts) Determinethe numberof moles of carbon,h)'drogenand nitrogen that are
Dresent:
6,?7\x
r #,
1,+aS
tr
rfT}. T"''6"'r'
moles
H: 0'870
h,J,(
1,131
^
,,/,
molesN:
o,lLv
(b) (4 pts) What is the empirical formula of the unknown compound?
Empincal formula=
9. (2 pts) Which one of the following is a nonelectrolyte?
a. aqueousBa(NO3)2soiution
b. aqueousCaCI2solution
c. aqueousLi3PO4solution
(]/ aqueousCH3OH solution
e. aqueousK2SO4solution
t't
Ctt-1,
10. (3 pts) The Vonitrogenby massin urea,(H2N)2CO,is:
a. 23.3Va
b.31.3Vo
c. 38.0Vo
(!
a6.77o
e. 60.9Vo
11. One of the stepsin the commercialprocessfor converlingammoniato nitnc acid
invoivesthe conversionof NHj to NO:
4 N H 3 ( g )+ 5 o z G ) + 4 N o ( g ) + 6 H 2 O ( g )
In a certainexperiment,2.50
gramsof NH3reactswith 2.85gramsof C2.
(a) (4 pts)How manymolesof NH3 and02 arebeingreacted?
0'i+'l
molesNH3=
moles02 =
0 ,081I
(b) (2 pts) Which reactantis the limiting reactant?
Limiting reactant=
0z
12. (3 pts) Write abalanced molecularequationfor the following reaction(usirtg
chentical J'ontulcts):
vrt(A
[chromium(Itr) hydroxide] + lperchloric acidl )
[chromium(Itr) perchlorate]+ [water]
+ iHctO -) (.(Ct
1\
i\$t'
q w
13. (3 pts) The empirical formula of a group of compoundsis CHCI. Lindane, a
powerful insecticide,is a memberof this group. The molecularmassof lindaneis 290.8
g mol '. Whatis themolecularformulaof iindane?
_1
a. CHCI
b. C2F^zCt2c. C4H4CI4@ ,u^urru
e. CsHsCls
14. (4 pts) Considerthe fermentationreactionof glucoseby yeast:
C6H12O6)
/ [on'
zCzHsOH + 2CO2
was placedin a vat with an excessof yeast. If 46.0
A i.00 mole sampleof C6H12O6
gramsof C2H5OH(molecularmass= 46.068g mol-l; was obtained,what is the Vo yield
o)
of C2H5OH?
" .{ i t
a. 100. Vo
b. 56.0vo
c. 42.0 Vo
t d . ) 5 0 . 07 o
e. 46.0Vo
15. (3 pts) Balancethe following reaction(entercorrectcoefficientsin the blanks):
| " r r n . r u * ? u r s ) J S n S 2L+r o
,i rt.,
1\,
pp{tt'
16. (2 pts) The following reactionis an exampieof
BaCl2(aq)+ H2SO4(aq))
BaSOa(s)+ 2HCl (aq)
a. an ionic redox reaction
b. an ionic acid-baseneutralizationreaction
c. a molecularacid-baseneutralizationreaction
( dJ a molecularprecipitationreaction
\-/
e. a molecularredoxreaction
17. (3 pts) In the reactionshownbelow, what speciesis being reduced?
2LiBr + C12> 2LiCl +Br2
a. Li+
b. Bi
c. ct-
d. Br2
@ rt,
18. (2 pts) Which one of the following compoundsis solublein water?
a.
NiCO3
b.
Pbso4
d.
AgCl
e.
Fe(OH)3
19. (5 pts) Sodiumacetate,NaC2H3O2,
hasa formulamassof 82.034g mol-'. What
concentration
is the molar
of a soiutionpreparedby dissolving4.10 -sramsof sodium
acetatein enoughwater to prepare250.0 mL of the solution?
molar
@ o.zoo
b. 1.025molar
c. 1.345moiar
,4
\u/
d . 2 . 0 0x 1 0 - am o l a r
e.76.4molar
24. G pts) Using the activity series,determinewhethereachof the following reactions
will occur. If a reactionoccurs,wnte the products;if no reactionoccurs,write "NO
REACTION''.
) Si
a. sr+Mg2*
h
co + Hg2*)
* ila
l+l + Co'+
21. (6 pts) Lactic acid,(HC3H5O3),
is a monoproticacidthat forms u,henmilk becomes
sour. In one laboratoryexercisefor studentstaking a food chemistrycourse,a 40.00
* sampleof an aqueousiactic acid solutionrequired26.50mL of 0.140molar
,SSg
'
NaOH (aq) to neutralizeit during the courseof a titration. From this data,what is the
molar concentrationof lactic acid in the solution?
,,;fu
uJ*t
@o.olzs
molar
e. 0.928moiar
b. 0.148molar
c. 0.271molar
d. 0.757moiar
22. (4 pts) Write the net ionic equationfor the reactionswhrch occur upon mrxing the
following substances:
HCIO4(aq) + Ba(OH)2(aq) )
(a)
rt sz) + aH;,t)
t
,',':ffiL7
, t *
i - \
^
Hrok)
'
Na2CO3(aq) + Iillo3 (aq) )
(b)
-) ilroA + co'ql
+ Cot'aU
ZHkzt
23. (3 pts) An aqueoussoiutioncontainsone soiutewhich is eithersodiumacetate,
sodiumsulfate,or potassiumnitrate. Addition of somebanum chlorideto a sample
of the solutioncausedthe formation of a white precipitate. Which of the three
(writerhechemicat
possibilities
wasthesoiure
fonnuta)?
SOrl lu^ Su lfr/<
21. (3 pts) Which of the following is an oxidation/reductionreaction?
2 A1(s) + 3 Br2fl) )
2 AiBr3Q)
l,
CaCO3(s) )
a
NiCl2(aq) + 2 AgNO3(aq))
Ll.
A
all of the above
e.
noneof the above
COzG) + CaO(s)
2 AgCl (s) + Ni(NO:)z(aq)
25. (4 pts) Predictthe productsand write the balancedmolecularequationfor the
folJowing
reaction.
!$b
t/
r
() ,,n,,^^, . \r- /-\
$'
"-|'
Hr(l)
rICl(aq)+ Mg(s)) My'lt-GL)
*
n"ult1-), ec
26. (2 pts) A dynamic equilibnum is reachedu'hen aceticacid is dissolvedin water.
Which of the speciesshown below is presentin the largestamountin solution?
a.
C2H302-(aq)
d.
H3O (aq)
L
H* (aq)
e.
oH-(aq)
+
HC2H3O2(aq)
27. For the following oxidation-reduction(redox)reactionwhich occursin acidic
solution:
I- +NO3-+NO2+IO3a. (3 pts) Write the balancedoxidationhaif-reaction
,r'.'[
3|ro+ 1- -r Io,
+ Le+6H+
(3 pts) Write the balancedreductionhalf-reaction
z t ] r + ^ t q -+ t e - , N o r + H r o
c. (3 pts) Write the overall balancedequation
A$o
(0/'a;
-,
bltr++b/v%+
T0r+
llU{
+
+
T3$r0+
+ a/r03
T_
3Hro