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CHEM 121 Practice Exam

Spring 2012

NAME__________________________________________________________________

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1)Convert 1.25 atm to mm Hg. 1)

A)875 mm Hg

B)1520 mm Hg

C)760 mm Hg

D)950 mm Hg

E)1000 mm Hg

2)The volume of a gas is proportional to the temperature of a gas is known as 2)

A)Ideal Gas Law

B)Charles's Law

C)Dalton's Law

D)Boyle's Law

E)Avogadro's Law

3)What volume will a balloon occupy at 1.0 atm, if the balloon has a volume of 7.6 L at 3.8 atm? 3)

A)2.0 L B)35 L C)29 L D)5.0 L E)17 L

4)A sample of 0.300 moles of nitrogen occupies 0.600 L. Under the same conditions, what number of

moles occupies 1.200 L?

A)1.50 moles B)6.00 moles C)0.33 moles D)0.600 moles

5)To what volume will a sample of gas expand if it is heated from 50.

H

C and 2.33 L to 500.0°C? 5)

A)5.58 L B)10.3 L C)4.38 L D)9.74 L E)17.9 L

6)A gas is at 35.0°C and 4.50 L. What is the temperature at 9.00 L? 6)

A)1.16°C B)343°C C)17.5°C D)70.0°C E)616°C

7)A syringe initially holds a sample of gas with a volume of 285 mL at 355 K and 1.88 atm. To what

temperature must the gas in the syringe be heated/cooled in order to have a volume of 435 mL at

2.50 atm?

A)466 K B)721 K C)572 K D)139 K E)175 K

8)What pressure (in atm) will 0.44 moles of CO 2

exert in a 2.6 L container at 25°C? 8)

A)0.35 atm B)3.6 atm C)8.6 atm D)4.1 atm E)4.7 atm

Which of the following gas samples would be most likely to behave ideally under the stated

conditions?

A)CO at 200 atm and 25°C

B)O

at 400 atm and 25°C

C)N

at 1 atm and-70°C

D)SO

at 2 atm and 0 K

E)Ne at STP

Using the graph below, determine the gas that has the lowest density at STP.

A)D

B)A

C)B

D)C

E)All of the gases have the same density at STP.

11)Determine the density of CO 2

gas at STP. 11)

A)1.80 g/L B)4.46 g/L C)1.96 g/L D)5.10 g/L E)2.24 g/L

12)A 0.334 g sample of an unknown halogen occupies 109 mL at 398 K and 1.41 atm. What is the

identity of the halogen?

A)Br 2

B)Ge C)Cl 2

D)I

E)F

13)A mixture of He, Ne and Ar has a pressure of 7.85 atm. If the Ne has a mole fraction of 0.47 and Ar

has a mole fraction of 0.23, what is the pressure of He?

A)3.7 atm B)1.8 atm C)5.5 atm D)4.2 atm E)2.4 atm

14)Determine the volume of O 2

(at STP) formed when 50.0 g of KClO 3

decomposes according to the

following reaction. The molar mass for KClO 3

is 122.55 g/mol.

2 KClO 3

(s)2 KCl(s) + 3 O 2

(g)

A)14.6 L B)12.3 L C)8.22 L D)13.7 L E)9.14 L

A 21.8 g sample of ethanol (C 2

H

OH) is burned in a bomb calorimeter, according to the following

reaction. If the temperature rises from 25.0 to 62.3°C, determine the heat capacity of the

calorimeter. The molar mass of ethanol is 46.07 g/mol.

C

H

OH(l) + 3 O 2

(g)2 CO 2

(g)+3 H 2

O(g) ̇ H° rxn

=-1235 kJ

A)15.7 kJ/°C B)5.65 kJ/°C C)33.1 kJ/°C D)4.99 kJ/°C E)63.7 kJ/°C

24)Using the following equation for the combustion of octane, calculate the heat of reaction for 100.0 g

of octane. The molar mass of octane is 114.33 g/mole.

2 C

H

+25 O

16 CO

+18 H

O ̇ H°

rxn

=-11018 kJ

A)

9.64 x 10

kJ B) 4.82 x 10

kJ C) 1.26 x 10

kJ D)4.82 kJ

25)A student is preparing to perform a series of calorimetry experiments. She first wishes to

determine the calorimeter constant (C cal

) for her coffee cup calorimeter. She pours a 50.0 mL

sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She

carefully records the final temperature of the water as 317 K. What is the value of C cal

for the

calorimeter?

A)99 J/K B)19 J/K C)76 J/K D)28 J/K E)21 J/K

26)Use the standard reaction enthalpies given below to determine ̇ H° rxn

for the following reaction:

P

(g) + 10 Cl 2

(g)4PCl 5

(s) ̇ H° rxn

Given:

PCl 5

(s)PCl 3

(g) + Cl 2

(g) ̇ H° rxn

=+157 kJ

P

(g) + 6 Cl 2

(g)4 PCl 3

(g) ̇ H° rxn

=-1207 kJ

A)-1786 kJ B)-1835 kJ C)-2100. kJ D)-1364 kJ E)-1050. kJ

27)Choose the reaction that illustrates ̇ H° f

for Ca(NO 3

A)Ca(NO 3

(aq)Ca

(aq)+2 NO 3

(aq)

B)

Ca

(aq) + 2 NO 3

(aq)Ca(NO 3

(aq)

C)Ca(NO 3

(s)Ca(s)+N 2

(g)+3O 2

(g)

D)Ca(s) + N 2

(g) + 3O 2

(g)Ca(NO 3

(s)

E)Ca(s) + 2 N(g) + 6 O(g)Ca(NO 3

(s)

Use the ̇ H° f

information provided to calculate ̇ H° rxn

for the following:

̇ H°

f (kJ/mol)

SO

Cl 2

(g) + 2 H 2

O(l)2 HCl(g) + H 2

SO4(l) ̇ H° rxn

SO

Cl 2

(g) - 364

H

O(l) - 286

HCl(g) - 92

H

SO

(l) - 814

A)-62 kJ B)-422 kJ C)+161 kJ D)-256 kJ E)+800. kJ

29)Place the following types of electromagnetic radiation in order of increasing wavelength.

ultraviolet light gamma rays radio waves

A)radio waves<ultraviolet light<gamma rays

B)ultraviolet light<gamma rays<radio waves

C)gamma rays<ultraviolet light<radio waves

D)gamma rays<radio waves<ultraviolet light

E)radio waves<gamma rays<ultraviolet light

30)Which of the following visible colors of light has the highest frequency? 30)

A)green B)red C)yellow D)orange E)blue

31)Calculate the wavelength (in nm) of a the red light emitted by a neon sign with a frequency of 4.

× 10

Hz.

A)142 nm B)466 nm C)158 nm D)704 nm E)633 nm

32)How many photons are contained in a burst of yellow light (589 nm) from a sodium lamp that

contains 609 kJ of energy?

A)

3.06× 10

photons

B)

3.37× 10

photons

C)

1.80× 10

photons

D)

4.03× 10

photons

E)

2.48× 10

photons

Calculate the wavelength of an electron (m=9.11× 10

g) moving at 3.66× 10

m/s.

A)

5.03× 10

m

B)

1.99× 10

m

C)

2.76× 10

m

D)5.

×

m

E)1.81× 10

m

34)Which of the following transitions (in a hydrogen atom) represent emission of the longest

wavelength photon?

A)n=1 to n= 2

B)n=3 to n= 4

C)n=3 to n= 1

D)n=5 to n= 4

E)n=4 to n= 2