Chemistry 1A, Exam I Name February 11, 2014 Professor …calche/wp-content/uploads/2011/10/... ·...

Chemistry 1A, Exam I Name ______________________________ February 11, 2014 Professor R.J. Saykally GSI ______________________________ 1. (40) _______________ 2. (40) _______________ 3. (40) _______________ 4. (40) _______________ 5. (40) _______________ TOTAL EXAM SCORE (200) _______________ Rules: • Work all problems to 2 significant figures • No lecture notes or books permitted • No programmable or graphing calculators permitted • Time: 90 minutes • Show all work to get partial credit • All answers must be written in the boxes provided • Periodic Table, Tables of Physical Constants, and Conversion Factors included

Useful Equations

E = mc2

E = h⌫

� =

c

⌫

�deBroglie

=

h

p=

h

mv

Ekin

(e�) = h⌫ � � = h⌫ � h⌫0

�x�p � h̄

2

=

h

4⇡

p = mv

En

=

h2n2

8mL2

En

= �Z2

n2R1

PV = nRT

M1V1 = M2V2

P1V1

n1T1=

P2V2

n2T2

vrms

=

r3RT

M

Ekin

=

3

2

RT

pH = �log[H3O+]

pX = �logX

Kw

= Ka

Kb

Kw

= [H3O+][OH�

] = 1.0⇥ 10

�14

pH + pOH = 14

pH =

1

2

(pka1 + pk

a2)

pH = pKa

+ log[A�

]

[HA]

k = Ae�Ea/RT

[A]

t

= [A]0e�kt

1

[A]

t

=

1

[A]0+ kt

ln[A] = �kt+ ln[A]0

t1/2 =

[A]0

2k

t1/2 =

ln 2

k

t1/2 =

1

k[A]0

ln

k1k2

=

Ea

R

✓1

T2� 1

T1

◆

q = mc�T

w = �Pext

�V

�E = qv

�H = qp

�H = �E + p�V

�H = �E +�nRT

�Ho

=

X�Ho

f

(products)�X

�Ho

f

(reactants)

�So

=

X�So

f

(products)�X

�So

f

(reactants)

�Go

=

X�Go

f

(products)�X

�Go

f

(reactants)

�Go

= �Ho � T�So

for aA+bB

*) cC+dD

Q =

[C]

c

[D]

d

[A]

a

[B]

b

At equilibrium, Q = K

�Go

rxn

= �nFEo

cell

Ecell

= Eo

cell

� 0.0257V

nlnQ

Eo

cell

=

RT

nFlnK

lnK = ��Ho

RT+

�So

R

Ptotal

= PA

+ PB

= XA

P o

A

+XB

P o

B

�T = ikb,fm

⇧ = iMRT

�G = �Go

+RT lnQ

S = kB

lnW

ln

P1

P2=

�Hvap

R

✓1

T1� 1

T2

◆

Mass%A =

mass of A in the whole

mass of the whole⇥ 100%

% error =

��experimental value� accepted value

acceptedvalue

��⇥ 100%

% yield =

actual yield

theoretical yield⇥ 100%

Physical Constants

Standard Acceleration of terrestrial gravity g = 9.80665 m s-2 (exactly)Avogadro's number N0 = 6.022137 x 1023

Bohr radius a0 = 0.52917725 Å =5.2917725 x 10-11 mBoltzmann's constant kB = 1.38066 x 10-23 J K-1

Electron Charge e = 1.6021773 x 10-19 CFaraday constant F = 96,485.31 C mol-1

Masses of fundamental particles:Electron me = 9.109390 x 10-31 kgProton mp = 1.672623 x 10-27 kgNeutron mn = 1.674929 x 10-27 kg

Ratio of proton mass to electron mass mp/me = 1836.15270Permittivity of vacuum ϵ0 = 8.8541878 x 10-12 C2 J-1 m-1

Planck's constant h = 6.626076 x 10-34 J sħ = h/(2π) = 1.054571 x 10-34 J s

Speed of light in vacuum c = 2.99792458 x 108 m s-1 (exactly)Universal gas Constant R = 8.31451 J mol-1 K-1 = 0.0820578 L atm mol-1 K-1

Rydberg Constant R∞ = 1.0973 x 107 m-1

R∞ = 2.18 x 10-18 J

Conversion FactorsStandard Atmosphere 1 atm = 1.01325 x 105 Pa = 1.01325 x 105 kg m-1 s-2 (exactly)Atomic mass unit 1 u = 1.660540 x 10-27 kg

1 u = 1.492419 x 10-10 J = 931.4942 MeV (energy equivalent from E = mc2)Calorie 1 cal = 4.184 J (exactly)Electron volt 1 eV = 1.6021773 x 10-19 J = 96.48531 kJ mol-1

Foot 1 ft = 12 in = 0.3048 m (exactly)Gallon (U.S.) 1 gallon = 4 quarts = 3.78541 L (exactly)Liter-atmosphere 1 L atm = 101.325 J (exactly)Metric ton 1 metric ton = 1000 kg (exactly)Pound 1 lb = 16 oz = 0.45359237 kg (exactly)

Average Bond Enthalpies

Single'Bonds'(kJ/mol)''' H' C' N' O' F' Si' P' S' Cl' Br' I'H' 436$ 413$ 391$ 463$ 565$ 318$ 322$ 347$ 432$ 366$ 299$C' 413$ 346$ 305$ 358$ 485$ ,,,$ ,,,$ 272$ 339$ 285$ 213$N' 391$ 305$ 163$ 201$ 283$ ,,,$ ,,,$ ,,,$ 192$ 243$ ,,,$O' 463$ 358$ 201$ 146$ 184$ 452$ 335$ ,,,$ 218$ 201$ 201$F' 565$ 485$ 283$ 184$ 155$ 565$ 490$ 284$ 253$ 249$ 278$Si' 318$ ,,,$ ,,,$ 452$ 565$ 222$ ,,,$ 293$ 381$ 310$ 234$P' 322$ ,,,$ ,,,$ 335$ 490$ ,,,$ 201$ ,,,$ 326$ ,,,$ 184$S' 347$ 272$ ,,,$ ,,,$ 284$ 293$ ,,,$ 226$ 255$ 213$ ,,,$Cl' 432$ 339$ 192$ 218$ 253$ 381$ 326$ 255$ 242$ 216$ 208$Br' 366$ 285$ 243$ 201$ 249$ 310$ ,,,$ 213$ 216$ 193$ 175$I' 299$ 213$ ,,,$ 201$ 278$ 234$ 184$ ,,,$ 208$ 175$ 151$

Double'Bonds' Triple'Bonds'

(kJ/mol)'C=C$ 602$ C≡C$ 835$O=O$ 498$ $$ $$C=O$ 732$ C≡O$ 1072$N=O$ 607$ $$ $$N=N$ 418$ N≡N$ 945$C=N$ 615$ C≡N$ 887$

Thermodynamic Parameters

! ΔH°f S° ΔG°f ! (kJ/mol) (J/mol!K) (kJ/mol)

H2(g) 0 131 0 O2(g) 0 205 0 CO2(g) &394 214 &394 H2O(g) &242 189 &229 H2O(l) &286 70 &257 NO2(g) 33.2 240 51 H2O2(g) &188 110 &120 C(s) 0 6 0 Mg(s) 0 33 0 MgO(s) &602 29 &569 C2H2(g) 229 201 209

CH3CH2OH(l) &298 161 &175 N2O4 9.2 304 98

C4H10(l) &125 310 &15.7 C3H8!(g) &104.7 269.91 &23.4

Perio

dic

Tabl

e of

the

Elem

ents al

kali

met

als

alka

line

eart

h m

etal

s

tran

siti

on m

etal

s

othe

r m

etal

s

met

allo

ids

nobl

e ga

ses

halo

gens

othe

r no

n-m

etal

s

unkn

own

chem

ical

pro

pert

ies

disc

over

y cl

aim

ed

1 3 11 19 37 55 87

1.01

6.94

22.99

39.10

85.47

132.91

(223)

4.003

20.18

39.95

83.80

131.29

(222)

9.01

24.31

40.08

87.62

137.33

226.03

10.81

26.98

69.72

114.82

204.38

12.01

28.09

72.64

118.71

207.2

14.01

30.97

74.92

121.76

208.98

15.999

32.06

78.96

127.60

(209)

18.998

35.45

79.90

126.90

(210)

44.96

88.91

138.91

227.03

47.90

91.22

178.49

140.12

140.91

144.24

(145)

150.36

151.96

157.25

158.93

162.50

164.93

167.26

168.93

173.04

174.97

232.04

231.04

238.03

237.05

(244)

(243)

(247)

(247)

(251)

(252)

(257)

(258)

(259)

(262)

(261)

50.94

51.996

92.91

95.94

180.95

183.84

(262)

(266)

54.94

(98)

186.21

(264)

55.85

101.07

190.23

(277)

58.93

102.91

192.22

(268)

58.69

106.42

195.08

(281)

63.55

107.87

196.97

(272)

65.41

112.41

200.59

4 12 20 38 56 88

21 39 57 89

22 40 72 104

23 41 73 105

24 42 74 106

25 43 75 107

26 44 76 108

27 45 77 109

28 46 78

29 47 79

30 48 80

13 31 49 81

32 50 8283

84

56 14

7 15 33 51

8 16 34 52

9 17 35 53 85

2 10 18 36 54 86

H Li Na K Rb Cs Fr

Be Mg

Ca

Sr Ba Ra

Sc Y La Ac

Ti Zr Hf

V Nb Ta

Cr Mo W

Mn

Re

Fe Ru Os

Co Rh Ir

Ni

Pd Pt DsRgCu Ag Au

Zn Cd Hg

Al Ga In TI

Ge Sn PbBi

Po

Sb

BC Si

N P As

O S Se Te

F Cl Br I At*

He Ne Ar Kr Xe Rn

CePr

Nd

SmEu

GdTb

DyHo

ErTm

YbLu

ThPa

U

Rf*

Tc**

*

Db*

Sg*

BhHs

Mt

Pm Np*

Pu*

Am**

Cm*

Bk*

Cf*

Es*

Fm*

Md*

No*

Lr*

5859

6061

6263

6465

6667

6869

7071

9091

9293

9495

9697

9899

100

101

102

103

Lant

hani

de se

ries

Actin

ide

serie

s

110

111

Hydrog

en

Lithium

Sodium

Potassium

Rubidium

Cesium

Fran

cium

Beryllium

Mag

nesium

Calcium

Strontium

Bariu

m

Radium

Scan

dium

Yttrium

Lantha

num

Actin

ium

Titanium

Zircon

ium

Hafnium

Rutherfordium

Vana

dium

Niobium

Tantalum

Dubn

ium

Chromium

Molybde

num

Tung

sten

Seab

orgium

Man

gane

se

Tech

netiu

m

Rhen

ium

Bohrium

Iron

Ruthen

ium

Osmium

Hassium

Coba

lt

Rhod

ium

Iridium

Meitnerium

Nickel

Palladium

Platinum

Copp

er

Silver

Gold

Zinc

Cadm

ium

Mercu

ry

Alum

inum

Gallium

Indium

Thallium

Germ

anium

Tin

Lead

Bism

uth

Polonium

Boron

Carbon

Silicon

Nitrog

en

Phosph

orus

Arsenic

Antim

ony

Oxygen

Sulfu

r

Selenium

Telluriu

m

Fluo

rine

Chlorin

e

Brom

ine

Iodine

Astatin

e

Helium

Neo

n

Argo

n

Krypton

Xeno

n

Rado

n

Ceriu

mPraseo

dymium

Neo

dymium

Prom

ethium

Samarium

Europium

Gado

linium

Terbium

Dysprosium

Holmium

Erbium

Thulium

Ytterbium

Lutetiu

m

Thorium

Protac

tinium

Uran

ium

Nep

tunium

Pluton

ium

Americium

Curiu

mBe

rkelium

Californium

Einsteinium

Ferm

ium

Men

delevium

Nob

elium

Lawrenc

ium

Darm

stad

tium

Roen

tgen

ium

*

Disc

over

ed a

t Law

renc

e B

erke

ley

Nat

iona

l Lab

orat

ory

**

Disc

over

ed in

Chi

cago

by

Ber

kele

y te

am **

* D

iscov

ered

in It

aly

usin

g a

sam

ple

from

Ber

kele

y cy

clot

ron

bom

bard

men

t

——

—(298.19)

—(293)

(285)

CnUu

tFl

Uup

Lv112

114

115

116

118

Cope

rnicium

Flerovium

Unun

pentium

113

Unun

trium

Liverm

orium

Uus

Uuo

117

Unun

septium

Unun

octiu

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CSO26

949

blac

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grey

solid

liqui

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lypr

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synt

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pre

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ter f

ound

in tr

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ture

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sym

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Chemistry 1A S’14, Exam I Name _________________________________ 1

1. (10 points each) Combustion of Butane A) Write the balanced chemical equation for the combustion of butane (C4H10).

B) Calculate the mass of water produced by the complete combustion of 10.0g of butane.

C) Calculate the pressure in a 2.00 liter container containing 10.0g of butane at 500K.

D) Calculate the mole fraction of butane in the above system if 0.500 atmosphere of oxygen are added to the butane


2. (10 points each) A mixture of 12.0g of H2(g) and 10.0g of O2(g) is combusted in a 1 liter vessel. A) Determine the limiting reagent.

B) 286 kJ of energy are released per mole of hydrogen reacted. Calculate the energy released from the above reaction.

C) Calculate the partial pressure of the H2O(g) produced assuming it is at 1000 K.


D) After the container has cooled back to its initial temperature, will the pressure in container be higher or lower as a result of the reaction? Why?

3. (10 points each) The Iodine Clock Reaction

A) Write the balanced chemical equation for the reaction of iodate (IO3

-) with iodide (I-) in acidic solution (H+) to produce iodine (I2) and water.

B) Calculate the volume of 0.100 M IO3

- solution that will exactly react with 10.0 mL of 0.200 M I- solution.


C) What volume of 0.100 M sulfite (SO32-) solution would be required to exactly react with the iodine

(I2) produced in B) above? The balanced reaction is: SO3

2- + I2 + H2O ! SO42- + 2I- + 2H+

D) Draw the best Lewis Structure for IO3-


4. (40 points total) I. (10 points) An unknown compound contains carbon, hydrogen, and oxygen. A 15.0 g of sample was combusted in an oxygen rich environment to produce 36.62 g of CO2 (g) and 14.99 g of H2O (g). What is the empirical formula of the unknown compound?


II. Iron reacts with water to produce iron (III) oxide (Fe2O3) and hydrogen gas. A. (5 Points) Write a balanced chemical reaction for the above reaction.

B. (10 points) If 6 L of water vapor at 60 °C and 0.120 atm reacts with excess iron, how many grams of iron (III) oxide will be produced.


III. (15 points) A 2.5 L flask contains 3.52 g of a colorless gas at 15 °C and 1.05 atm. Is the gas CO2, CO, or O2?

!


5. (10 points each) For the following compounds: A. Draw the Lewis Structure, explicitly showing the formal charges and molecular geometry B. Indicate the Electron Pair Geometry C. Indicate the Molecular Geometry I. Sulfite (SO3

2-)

II. Carbon Monoxide (CO)

III. Ammonia (NH3)

A. B. C.

A. B. C.

A. B. C.


IV. Carbonate ion (CO32-)

A. B. C.

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