chem 1021, fall 2000 final dec. 19, 2000 prof. j. t...

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CHEM 1021, Fall 2000Prof. J. T. Roberts

Final Dec. 19, 2000

DO NOT OPEN THE EXAM UNTIL THE PROCTOR TELLS YOU TO DO SO

Instructions :

1. There are 36 problems, each worth 5 points. They are distributed betweenParts I, II, and III (10 problems each) and Part IV (6 problems). Parts I-IIIcorrespond to the material covered on Exams 1-3, respectively.

2. There are 17 pages, including a cover page (this page), a page of usefulconstants and equations, and a periodic table.

3. Fill in the bubble sheet with your name (last name first) and ill number. ~easoft lead pencil to do this. Make sure that your answer sheet indicates thecorrect test version. (This is version A). This information must be enteredcorrectly, or your test will not be scored properly.

4. Write the special code that is printed on your bubble sheet here: my code forthe Final is .This is a unique code for your test. Test results andfinal grades will be posted by this number only on the class web page. Gradeinformation will not be released over the telephone or by e-mail.

5. All of the problems are multiple choice. Mark the letter (a-e) on your answerbubble sheet of the one choice that best answers the question. There is nopartial credit, and you need not show your work. Use scratch paper or thebacks of the exam pages if you need space to work. \

6. You are permitted to have one 8.5" x 11" sheet of paper containing anyinformation you wish written or printed on both sides. There is a periodic tableattached to the back of the exam.

7. You must remain seated until the exam is officially over. All answer sheetswill be collected at the same time. Hand in the answer sheet only. Keep yourcopy of the exam for self-scoring.

8. The answer key will be available on the class home page(http://www.chem.umn.edu/classl and follow the links) by tomorrow morning.Test results and final grades will be posted on the class web page by Fridayafternoon.

J~ E i -!\

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PART I (material covered on first exam).

1. Which of the following could be both an empirical and a molecular fonnula?

(a) C~1206 ~~j> Ir,' c.c l l'~ C ~~ O

(b) N2F 4 (. ~ p , ,. I' ( c.. \ i ~ t\J F l.

0(c) 03

@HNF2

(e) C2~02

\~e. ~y I.,. ~ c c...

c 1..1 ?" 0i ~e..~1>'r'" i'c~

~---cSulfur trioxide, SO3, is made from the oxidation of SO2. The balanced equation for

the reaction is:2.

2 802 + 02 ~ 2 803

A 16 9 sample of 802 is oxidized according to the above reaction to produce 18 g of

803. What is the percent yield of 803 ?

I ",ol.f S'~ A ""O~ SOJ-

~ M0/-f EIJ '2,.

(a) 60%

(b) 75%

(c) 80%

@90%(e) 100%

1 "f~.(oY'"(. ~ i (~

Mok SOJ

'2t lao

~

p~rc.-et\.f

3 Energy from the following reaction provided the lift for the moon lander.

-(CH3hN2H2 + -N2O4 ~ -N2 + -H20 + -CO2

What is the coefficient in front ofN2 when the reaction is balanced? (Note: Allcoefficients of the balanced reaction must be the lowest possible integers.)

(a) 1

(b) 2

@3

(d) 4

(e) 5

~~Ol-)., 4

4. In which of the following compounds does the underlined element have an oxidationnumber of +2?

@n( OH)42-

(b) .crO2C12

(c) HNO2 ,(d) :f~ +

(e) NO2

tY'\ (-I 2.)

Cr(-4-b)

!\J (+ 5"')

p -3)

f\J (011.1)

1 ~~The hormone testosterone has a formula mass of288.4 g.mol- and contains 79:12%carbon by mass. How many carbon atoms are in each testosterone molecule?

(a) 17 ().:}91'J..

@3>19(c) 21 ?'.l <6 .I ~ c..-I.A t ~

( d) 23

( e) 28

5.

""yY'\\..A...):- ~~~ <6 c. ~1

\ c...~o \""I. c.. I \ 1. .o I c.. V"'"

\9

~

c.. ( O t'Y\ .)

6.

'L0. h5' Y"""olL / lOOO r"'IJ. "'

O.(JOb~(i: r"'O -t'J-

How many moles ofKOH are in 27.5 ml of 0.250 M KOH?

(a) 0.00431 moles

@0.00688 moles A. ?!;I"'\.{ i

(c) 0.00724 moles

(d) 0.00813 moles

(e) 0.00921 moles

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7,

t'\u

...

T

.(

T

\/

~~

For an ideal gas, which of the following statements are true?

I. P is proportional to T at constant n and V

II. P is proportional to Vat constant n and T

III. V is proportional to T at constant n and P

IV. n is proportional to Vat constantP and T

(a) I and II only

(b) III and IV only

(c) II only

(d) I and III only

@,III, and IV only

The correct formula for magnesium phosphate is

(a) MgPO4. ~c..~,,~s I~V"\

@})M~(PO4h. -(c) Mn2(PO4)3. p hos'P hc.-~.(. ~

( d) Mg2(PO4)3.

(e) Mn3(PO4)2.

8.1..\

\'I'~

)-

'P o~

-=

Maleic acid contains 41.4% C, 3.47% H, and 55.1% O by mass. A 0.0500 molesample of this compound has a mass of5.80 g. What is the molecular formula ofmaleic acid?

9,

O )5". J

J<o.ou

(a) CHO

(b) C2H202

(C) C3H30

~C4fI404

(e) C~O6

::-}~ 1.11.1.1-, '), .(>I

t~ 3.l11

-

I. () I

~ M 'P i... I' c. ~ \

forM"'-\~ ) ~OJ !o.oS-OO ~oM(,.. '>S

jV'-\olb. ~

I/V

,./

)

v

J~ELf-A

o.qoo

3. LI (,)O.olloAfcrlt

3.465

(a) 0.300000

(b) 0.30000

(c) 0.3000

@2».300(e) 0.3

O.ZbO -I o.OttO ~sql

~~

0.300

~~.~

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-(:),~ E y

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-1!rv~o~~J..Jt~. , <j~-O

rro.oj) '7..3. 3°C. -~oBc:..)

PART n (material covered on second exam).

11. A 150.0 9 sample ofa metal at 80.0 °C is added to 150.0 9 ofH2O at 20.0 °C. Thefinal temperature of the system is 23.3 °C. Assuming that the calorimeter is a perfectinsulator, what is the specific heat capacity of the metal? The specific heat capacityofH2O is 4.18 J.g-I.oC-I. -~

(a) -048 J.g-I.oC-1 Cp ---:..11'\. ~ I

~0.24 J.g-I.oC-1

(c) 0.48 J.g-I.oC-1 :

(d) 0.72 J.g-I.oC-1

(e)0.96J.g-1.oC-1 -O.:Z.I.I T/1.oc ~'

12. The properties of a real gas are most likely to deviate from those of an ideal gas when

(a) the pressure is low.

(b) the temperature is high.

@ the pressure is high and the temperature is low.

( d) the pressure is low and the temperature is high.

(e) All of the situations (a)-(d) would result in significant deviation fromideality .

1c...1..A.)

13. Three 1.0 L flasks are filled with H2, 02, and NH3, respectively, at STP. Which of thefollowing statements is true?

@ All flasks have the same number of gas molecules. Av\) ~ c..JY" (). ..s

(b) The average speeds of the gas molecules are the same in all of the flasks.

(c) The densities of all the gases are the same.

( d) There are half as many H2 molecules as NH3 molecules.

(e) None of the above statements (a)-(d) is true.

1( J

14. Given the following data, calculate the heat required to convert solid sulfur to gaseous

sulfur at 298 K and 1 atm pressure.

S(s) + O2 (g) ~ S02 (g) LVJ;98 K = -395 kJ

S(g) + O2 (g) ~ S02 (g) LVJ;98 K = -618 kJ

(a) -1013 kJ.mol-l~ / J L G c-

.,. 0 -) '>d"ll -;) 1 .)(b) +618 kJ.mor1 ~ ( S) C ~) S 1.(~)

(c) -618 kJ.mol-l / -~ / ~ b-) ~ ()/~ ( ~)

(d) -223 kJ.mol-l -

@223 kJ.mor1

/<6 k J

~(~)

5(~)-)s(S)

15. The number of molecules in 10.0 liters of air at 0 °C and 1.0 atm pressure is(a) less than 1020. Y\ ~ .-.,..

(b) between 1020 and 1021.(c) between 1021 and 1022. h :- ( \.

(d) between 1022 and 1023.

@etween 1023 and 6 x 1023. ~I

rv:

L .c..~" /r"tcl~ 1<

"13 k'

O .l{ L I ~ rV\() \n:~() '\ J / (,)lJ :

1.. ~ "'110t\)= (O.l\llb r"\O\

16. Which of the following atoms has the smallest atomic radius?

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(a)

(b)

(c)

(d)

Ha

Ca

As

At

/) e \'f -j),

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17. What is the energy contained in a single quantum of orange light with a frequency of5.00 x 1014 S-l?

(a) 1.25 x 10-48 J ~ -= h U-

Vh)n.31xI0-19J ." 1 ~ " 01"9~ : ( ~. b3 ~(c) 1.88 x 105 J

(d)3.13xI013J : 3.3

(e) 6.02 x 1023 J

-1 LI -

\0 J s

-1'1

\0 "1I 1-

19. Which of the following sets of quantum numbers are allowed?

1

10

3

2

!1 ll1l

-7

O

1

m.r.

+1/2

-1/2

+1/2

'1.C.S

'1.(.5

'1~..S

I. 11

II. 4

III. 3

(a) lonly

(b) II only

(c) III only

(d) I and II only

(JI~£ y -

20. Which ofthe following atoms has the highest ionization energy for removal ofthethird electron? ( rJ

~g Il's /v1j I be.cc...l,..,st ~A( 3- ~/~(fY'oV\

(b) Al c.. ~ J.(OM~ J r '.C)M c...n f\ -=. z.

(c) Sl

( d) Cl I~ 1. ~ ,. .s i S O of...l.( c. ~ Y' O I"\ I' <..

(e) Ar ~

J.e \I-{ I

\.A..) I ~ h }\Je

~~;:::

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PART ill (material covered on third exam).

21. Which of the following species is best described by two or more resonancestructures?

(d)

~c, ~ ---(b)H~/C...".CH3

H-~N(e)

F--r-F

F

(c)

J-J -c. -:=: c.. -l 4

r...' ~ ~0-

0-- 0--",

'2..1't'

22. In the acetylene, C2H2, molecule, there are

(a) five a bonds.

(b) two a bonds and three 1t bonds.

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(c) five 7t bonds.

( d) four 0' bonds and one 7t bond.

r>rI~ E '1' -

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~(.(~C..~\'\.I~?",-lV'j'l::--3(}

if'"

.0,

25. The 0-0-0 angle in ozone, 03, is

(a) 180°.

(b) 120°.

@slightly less than 120°.

(d) 109.5°.

(e) slightly less than 109.5°,

~'-

26. Which of the following is a substitution reaction?

(a) 2 CH30H + 3 02 ~ 2 C02 + 4 H20

(b) C2~ + 3 02 ~ 2 CO2 + 2 H20

(c) C2~ + Cb ~ C2~Cb

W2lI6 + Cb ~ C2HsCI + HCI

( e) HCOOH + CH30H ~ HCOOCH3 + H20

27. How many valence electrons does a sulfate ion have?

(a) 18 '1,.- (, -(b) 20 ~OLJ ~

\(c) 24 S

( d) 26

~2

(, e- J

~

"'2-.e..

t

-~~e..

Ll...""

0

28. For which of the following reactions is AH equal to the electron affinity ofl?

@1<8) + e- -+ r (8)

(b)h(8) -+ 21(8)

-1- e"(c) I(g) -+ r (g) .

(d) N~g) + l(g) -+ Nal{s)

(e) N3(s) + ~ h(s) -+ Nal{s)

29. Which ofthe following molecules has a non-zero dipole moment?

l(a~OOH ..,~. , "\. ..~.L L/ -- 0 -( -O(b) CO2 / '\ ,1 \

(c) HCCH 4

(d) SF6

(e) PFs

F,= -I ---1'"=:r::- --S -r::\ J~ -C-~ C.--

Fj':.

1--=I.f :::? -F

I

..J

r:30. In the hydronium ion, H30+, VSEPR theory predicts that the valence electro~r~arranged about the central oxygen atom at the comers of a .

(a) pyramid-

@ tetrahedron. Ll vc..l~ I'\('.( 1> ~ iv .s

( c) trigonal plane-

( d) bent structure.

( e) square plane.

..

I.} -<? -H

11

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}<ty- A

PART IV (material covered since the third exam).

31. Which of the following compounds is an ether?

(a) CH3COCH3I

(b ) CH300CH3 ~ -0 -~

@CH30CH3( d) CH3CH2OH

(e) CH3COOH

~<~32. Na20 forms an antifluorite cubic lattice in which the negative ions form a face-

centered cubic lattice and the positive ions occupy all tetrahedral sites. The numberof sodium ions in a single unit cell is

<6}"

II~)1

(a) 3

(b) 4

(c) 6

@8

(e) 12

[cc.

~

, ~o -5~-t(

~

( c...t(. c. (3 (' n.c. .~

,-

0

1Jc... .t

LI c.. 10"",5 C.f...p-er

p-.tr

33. Which of the substances below has the highest boiling point?

(a) CH3CH2CH3

(b) CH3CH2CH2CH3

(c) CH30CH3

@CH3CH20H 'h1Jrc~~V\ \:>oV\J.s

(e) CH3CH2F

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1" f y -A

34. Neon atoms do not combine to form Ne2 molecules, yet neon atoms can be liquifiedthrough the following intermolecular forces:

(a) dipole-dipole.

(b) ion-dipole.

(c) dipole-induced dipole.

~ondon dispersion.

(e) nonmetal-nonmetal.

~c~35. In a certain mountain range, water boils at 91 °C. What is the pressure under t1lese

conditions? The enthalpy ofvaporization ofwater is 44.0 kJ.mol-l.

@535 torr A f1. \ -I?J: }.. -..J )(b)575torr Y\ fl ) -R I, IL

(c) 615 torr l=. \ LI 4 OOOJ/ ~()

(d) 645 torr )Y\ ? bO ~otr ) ,,-

( e) 685 torr

V'l.. lOfr

36. At room temperature and pressure, SiO2 is an example of

(a) a polar molecular gas.

(b) a nonpolar molecular gas.

@)). covalent network solid.

( d) an ionic solid.

( e ) a metallic solid.

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