CHE 105 Fall 2019 Exam 3

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Question #: 1

A metal object with a mass of 29.5 g is heated to 97.0 °C and then transferred to an insulated container of 97.3 g of water at 20.5 °C. At thermal equilibrium, the temperature is 24.1 °C. What is the specific heat of the metal object? Assume all of the heat lost by the metal object is absorbed by the water. The specific heat of water is 4.184 J/g·°C.

A. 0.054 J/g·°C

B. 0.68 J/g·°C

C. 0.28 J/g·°C

D. 2.9 J/g·°C

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Question #: 2

Consider the energy diagram for the reaction: reactants →products. You may need to scroll down to see the entire question.

The reaction is 1 [endothermic or exothermic]. The sign of ΔH for this reaction is 2 [positive or negative].

1.

2.

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Question #: 3

Zn metal reacts with hydrochloric acid according to the balanced equation Zn(s) + 2 HCl(aq) →ZnCl2(aq) +H2(g) .

When 1.00 g of Zn metal is completely reacted with 100.0 g of 0.500 M HCl(aq) in a constant-pressure calorimeter, the temperature of the solution was observed to rise from 20.30ºC to 30.50ºC. What is the change in enthalpy for the reaction (as written) per mole of Zn(s)? Use 4.18 J/g·ºC for the specific heat capacity of the solution. Assume no heat is lost to the surroundings.

A. –759 kJ/mol Zn

B. –282 kJ/mol Zn

C. –30.4 kJ/mol Zn

D. –416 kJ/mol Zn

____________________________________________________________________________

Question #: 4

How many kJ of heat are produced by the combustion of 24.3 g of benzene (C6H6, molar mass: 78.114 g/mol)? 2 C6H 6 (l) + 15 O 2(g) →12 CO2(g) + 6 H2O(g) ΔH°rxn = –6278 kJ

A. 0.302 kJ

B. 3190 kJ

C. 976 kJ

D. 40.1 kJ

____________________________________________________________________________

Question #: 5

What is ΔH for the reaction 2 CH3OH(l) → 2 C(s) + 4 H2(g) + O2(g) given C(s) + 2 H2(g) + ½ O2(g)→ CH3OH(g) ΔH = –238.4 kJ. 1 kJ Report your answer with four significant figures. Do NOT include units with your answer.

1.

____________________________________________________________________________

Question #: 6

Calculate ΔHrxn for the reaction: Cu(s) + ½O2(g) → CuO(s) given, . 2 Cu(s) + S(s) → Cu2S(s) ΔH = –75.9 kJ S(s) + O2(g) → SO2(g) ΔH = –297 kJ Cu2S(s) + 2 O2(g) → 2 CuO(s) + SO2(g) ΔH = –528 kJ

A. –35.1 kJ/mol

B. –66.1 kJ/mol

C. –153 kJ/mol

D. –314 kJ/mol

____________________________________________________________________________

Question #: 7

Which reaction represents ΔH°f, the standard enthalpy of formation, for CH4? .

A. CH4(g) →C(s) + 2 H2(g)

B. C(s) + 4 H(g) →CH4(g)

C. C(s) + 2 H2(g) →CH4(g)

D. 2C(s) + 4 H2(g) →2 CH4(g)

E. Both c) and d)

____________________________________________________________________________

Question #: 8

What is ΔH°rxn? CH4(g) + 4 Cl2(g) →CCl4(g) + 4 HCl(g) .

Compound ΔH°f (kJ/mol)

CH4(g) –75

CCl4(g) –96

HCl(g) –92

.

A. 79 kJ

B. –584 kJ

C. –127 kJ

D. –389 kJ

____________________________________________________________________________

Question #: 9

Calculate the energy of electromagnetic radiation emitted from a radio station with a frequency of 96.1 MHz. 1 joules Report your answer using three significant figures. Use scientific notation in the format 2.22e3 or 2.22e-3. Do NOT include units in your answer.

1.

____________________________________________________________________________

Question #: 10

Rank x-rays, microwaves, and visible light in order of increasing (shortest to longest) wavelength. shortest 1 < 2 < 3 longest

1.

2.

3.

____________________________________________________________________________

Question #: 11

A burst of green light (wavelength 550 nm) has a total energy of 5.50 ×10–17 J. How many photons does it contain? Report your answer with three significant figures. Do NOT include units in your answer. Use the format 2.22e2 or 2.22e-2 for scientific notation. 1 photons

1.

____________________________________________________________________________

Question #: 12

What is the longest possible wavelength of electromagnetic radiation that could eject electrons from the surface of tungsten metal, which has a work function of 7.42×10–19 J?

A. 268 nm

B. 594 nm

C. 65.2 nm

D. 1120 nm

____________________________________________________________________________

Question #: 13

What is the energy of the photon emitted when an electron in a hydrogen atom transitions from the n=6 level to the n=2 level? Report your answer with two significant figures. Do NOT include units in your answer. Use the format 2.2E2 or 2.2E-2 for scientific notation.

1 J

1.

____________________________________________________________________________

Question #: 14

What is the de Broglie wavelength (in nm) of a beta particle (mass = 9.11 ×10–31 kg) traveling at the speed of light?

A. 8.82 ×10–3 nm

B. 1.08 ×10–3 nm

C. 2.42 ×10–3 nm

D. 3.42 ×1038 nm

____________________________________________________________________________

Question #: 15

Heisenberg's uncertainty principle can be expressed as:

where Δx is the uncertainty in the position, and Δv is the uncertainty in the velocity of an object. Select the two true statements which follow from the uncertainty principle.

A. The more certainty we have in the position of a particle, the more certainty we have in its

velocity.

B. The more certainty we have in the position of a particle, the less certainty we have in its

velocity.

C. If we know precisely the position of a particle, we know nothing about its velocity.

D. If we know precisely the position of a particle, we also know precisely its velocity.

____________________________________________________________________________

Question #: 16

Which set of quantum numbers is not allowed?

A. n = 4, l = 2, ml = 1, ms = +½

B. n = 1, l = 0, ml = 0, ms = –½

C. n = 3, l = 2, ml = 3, ms = +½

D. n = 2, l = 1, ml = –1, ms = –½

____________________________________________________________________________

Question #: 17

Which choice incorrectly matches the name of the orbital with the shape of the orbital?

A.

s orbital

B.

p orbital

C.

f orbital

D.

d orbital

____________________________________________________________________________

Question #: 18

Which statement concerning quantum numbers is false?

A. Multiple electrons in the same atom can share the same value for the principal quantum

number.

B. Multiple electrons in the same atom can share the same values for the principal and

angular momentum quantum numbers.

C. Multiple electrons in the same atom can share the same values for the principal, angular

momentum, and magnetic quantum numbers.

D. Multiple electrons in the same atom can share the same values for the principal, angular

momentum, magnetic, and spin quantum numbers.

____________________________________________________________________________

Question #: 19

The number of unpaired electrons in a neutral atom of krypton in its ground state is 1 . Report your answer as a whole number. The electron configuration of this atom indicates that it is 2 [diamagnetic, paramagnetic].

1.

2.

____________________________________________________________________________

Question #: 20

A ground-state Cl atom has 1 core electrons and 2 valence electrons. Report each answer as a whole number. Do NOT include units in your answer.

1.

2.

____________________________________________________________________________

Question #: 21

What is the electron configuration of a neutral silver atom in its ground state?

A. [Kr]5s24d9

B. [Kr]5s24d10

C. [Kr]5s14d9

D. [Kr]5s14d10

____________________________________________________________________________

Question #: 22

Which electrons in the ground-state of a neutral magnesium atom experience the greatest amount of shielding?

A. 1s electrons

B. 2s electrons

C. 2p electrons

D. 3s electrons

E. 3p electrons

____________________________________________________________________________

Question #: 23

Because the effective nuclear charge of carbon is 1 [greater than, equal to, less than] nitrogen, the atomic radius of carbon is 2 [greater than, equal to, less than] nitrogen.

1.

2.

____________________________________________________________________________

Question #: 24

For the isoelectronic series, which is in order of increasing (smallest to largest) size?

A. F– <O2– <Mg2+ <Na+

B. Mg2+ < Na+ < F– <O2–

C. O2– < F– <Na+ < Mg2+

D. Na+ < Mg2+ < O2– <F–

____________________________________________________________________________

Question #: 25

Which periodic table illustration shows the correct trend for the 1st ionization energy (IE)?

A.

B.

C.

D.

____________________________________________________________________________

Question #: 26

The ionization energies (in kJ/mol) of a second period element are given below. Which element is it? IE1 = 899 IE2 = 1757 IE3 = 14850 IE4 = 21005

A. Li

B. Be

C. B

D. C

E. N

____________________________________________________________________________

Question #: 27

Electron affinity is the energy associated with which reaction?

A. X(g) +e– →X–(g)

B. X(g) →X+(g) + e–

C. X–(g) →X(g) + e–

D. X+(g) + e– →X(g)

____________________________________________________________________________

Question #: 28

Which option lists the elements in order of increasing metallic character?

A. Ba <K <Mg <Na

B. K <Mg <Na <Ba

C. Ba <K <Mg <Na

D. Na <Mg <K <Ba

____________________________________________________________________________

Question #: 29

What is the electron configuration of the most common aluminum cation?

A. [Ne]

B. [Ne]3s2

C. [Ne]3s23p1

D. [Ne]3s1

E. [Ne]3s23p6

____________________________________________________________________________

Question #: 30

Select the two answers which correctly complete the statement: "Ionic bonds form ___"

A. between a metal and a non-metal.

B. between two non-metals.

C. between two metals.

D. due to electrostatic attractions as a result of electron transfer.

E. when electrons are shared between atoms.

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CHE 105 Fall 2019 Exam 3 - Confidential

Your Name: Your ID:

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Question #: 1

A metal object with a mass of 29.5 g is heated to 97.0 °C and then transferred to an insulated

container of 97.3 g of water at 20.5 °C.  At thermal equilibrium, the temperature is 24.1 °C. 

What is the specific heat of the metal object?  Assume all of the heat lost by the metal object is

absorbed by the water.  The specific heat of water is 4.184 J/g·°C.  

A. 0.054 J/g·°C

✓B. 0.68 J/g·°C C. 0.28 J/g·°C D. 2.9 J/g·°C

Question #: 2

Consider the energy diagram for the reaction: reactants →products. You may need to scroll down

to see the entire question.

The reaction is     1     [endothermic or exothermic].

The sign of ΔH for this reaction is     2     [positive or negative].

 

1. exothermic

2. negative

Question #: 3

Zn metal reacts with hydrochloric acid according to the balanced equation

Zn(s) + 2 HCl(aq) →ZnCl2(aq) +H2(g) .

When 1.00 g of Zn metal is completely reacted with 100.0 g of 0.500 M HCl(aq) in a constant-

pressure calorimeter, the temperature of the solution was observed to rise from 20.30ºC to

30.50ºC.  What is the change in enthalpy for the reaction (as written) per mole of Zn(s)

? Use 4.18 J/g·ºC for the specific heat capacity of the solution.  Assume no heat is lost to the

surroundings.

A. –759 kJ/mol Zn

✓B. –282 kJ/mol Zn C. –30.4 kJ/mol Zn D. –416 kJ/mol Zn

Question #: 4

How many kJ of heat are produced by the combustion of 24.3 g of benzene (C6H6, molar mass:

78.114 g/mol)?

2 C6H  6  (l) + 15  O 2(g) →12 CO2(g) + 6 H2O(g)     ΔH°rxn = –6278 kJ

.

A. 0.302 kJ B. 3190 kJ

✓C. 976 kJ D. 40.1 kJ

Question #: 5

What is ΔH for the reaction 2 CH3OH(l) → 2 C(s) + 4 H2(g) + O2(g)

given C(s)  + 2 H2(g) + ½ O2(g)→  CH3

OH(g)      ΔH = –238.4 kJ.

     1      kJ

Report your answer with four significant figures. Do NOT include units with your answer.

1. 476.8|+476.8|4.768e2|

Question #: 6

Calculate ΔHrxn for the reaction:

Cu(s) + ½O2(g) → CuO(s)  given,

.

 

A. –35.1 kJ/mol B. –66.1 kJ/mol

✓C. –153 kJ/mol

2 Cu(s) + S(s)  Cu2S(s) H = –75.9 kJ

S(s) + O2(g)  SO2(g) H = –297 kJ

Cu2S(s) + 2 O2(g)  2 CuO(s) + SO2(g) H = –528 kJ

D. –314 kJ/mol

Question #: 7

Which reaction represents ΔH°f, the standard enthalpy of formation, for CH4?

.

A. CH4(g) →C(s) + 2 H2(g) B. C(s) + 4 H(g) →CH4(g)

✓C. C(s) + 2 H2(g) →CH4(g) D. 2C(s) + 4 H2(g) →2 CH4(g) E. Both c) and d)

Question #: 8

What is ΔH°rxn?

CH4(g) + 4 Cl2(g) →CCl4(g) + 4 HCl(g)

.

.

A. 79 kJ B. –584 kJ C. –127 kJ

✓D. –389 kJ

Question #: 9

Calculate the energy of electromagnetic radiation emitted from a radio station with a frequency

of 96.1 MHz.  

    1     joules

Compound H°f (kJ/mol)

CH4(g) –75

CCl4(g) –96

HCl(g) –92

Report your answer using three significant figures.  Use scientific notation in the format 2.22e3

or 2.22e-3.  Do NOT include units in your answer.

1. 6.37e-26

Question #: 10

Rank x-rays, microwaves, and visible light in order of increasing (shortest to longest)

wavelength.

shortest        1     <     2     <     3       longest

1. x-ray|x-rays|xray|xrays|

2. microwave|microwaves|

3. visible light|visible|

Question #: 11

A burst of green light (wavelength 550 nm) has a total energy of 5.50 ×10–17 J. How many

photons does it contain?

Report your answer with three significant figures. Do NOT include units in your answer.  Use

the format 2.22e2 or 2.22e-2 for scientific notation.

    1     photons

1. 152|1.52e2|

Question #: 12

What is the longest possible wavelength of electromagnetic radiation that could eject

electrons from the surface of tungsten metal, which has a work function of 7.42×10–19 J?

✓A. 268 nm

B. 594 nm C. 65.2 nm D. 1120 nm

Question #: 13

What is the energy of the photon emitted when an electron in a hydrogen atom transitions from

the n=6 level to the n=2 level?

Report your answer with two significant figures. Do NOT include units in your answer. Use the

format 2.2E2 or 2.2E-2 for scientific notation.

    1     J

1. 4.8E-19|4.7E-19|4.9E-19|4.8e-19|4.7e-19|4.9e-19|

Question #: 14

What is the de Broglie wavelength (in nm) of a beta particle (mass = 9.11 ×10–31 kg) traveling at

the speed of light?

A. 8.82 ×10–3 nm B. 1.08 ×10–3 nm

✓C. 2.42 ×10–3 nm D. 3.42 ×1038 nm

Question #: 15

Heisenberg's uncertainty principle can be expressed as:

where Δx is the uncertainty in the position, and Δv is the uncertainty in the velocity of an object.

Select the two true statements which follow from the uncertainty principle.

A. The more certainty we have in the position of a particle, the more certainty we have in its

velocity. ✓B. The more certainty we have in the position of a particle, the less certainty we have in its

velocity. ✓C. If we know precisely the position of a particle, we know nothing about its velocity.

D. If we know precisely the position of a particle, we also know precisely its velocity.

Question #: 16

Which set of quantum numbers is not allowed?

A. n = 4, l = 2, ml = 1, ms = +½ B. n = 1, l = 0, ml = 0, ms = –½

✓C. n = 3, l = 2, ml = 3, ms = +½ D. n = 2, l = 1, ml = –1, ms = –½

Question #: 17

Which choice incorrectly matches the name of the orbital with the shape of the orbital?

A.  

 

B.

 

✓C.

 

D.

s orbital

p orbital

f orbital

 

Question #: 18

Which statement concerning quantum numbers is false?

A. Multiple electrons in the same atom can share the same value forthe principal quantum number.

B. Multiple electrons in the same atom can share the same values forthe principal and angular momentum quantum numbers.

C. Multiple electrons in the same atom can share the same values forthe principal, angular momentum, and magnetic quantumnumbers.

✓D. Multiple electrons in the same atom can share the same values forthe principal, angular momentum, magnetic, and spin quantumnumbers.

Question #: 19

The number of unpaired electrons in a neutral atom of krypton in its ground state is     1    .

 Report your answer as a whole number.

The electron configuration of this atom indicates that it is     2     [diamagnetic, paramagnetic].

1. 0|zero|

2. diamagnetic

Question #: 20

A ground-state Cl atom has     1     core electrons and     2     valence electrons.

Report each answer as a whole number. Do NOT include units in your answer.

d orbital

 

1. 10

2. 7

Question #: 21

What is the electron configuration of a neutral silver atom in its groundstate?

A. [Kr]5s24d9

B. [Kr]5s24d10

C. [Kr]5s1

4d9

✓D. [Kr]5s14d10

Question #: 22

Which electrons in the ground-state of a neutral magnesium atomexperience the greatest amount of shielding?

A. 1s electrons B. 2s electrons C. 2p electrons

✓D. 3s electrons E. 3p electrons

Question #: 23

Because the effective nuclear charge of carbon is     1      [greater than, equal to, less than]

nitrogen,

the atomic radius of carbon is     2     [greater than, equal to, less than] nitrogen.

1. less than|less|

2. greater than|greater|

Question #: 24

For the isoelectronic series, which is in order of increasing (smallest to largest) size?

A. F– <O2– <Mg2+ <Na+

✓B. Mg2+ < Na+ < F–

<O2–

C. O

2– <

 F

– <Na

+ < Mg

2+

D. Na+ 

< Mg2+

 < O2– <F

–

Question #: 25

Which periodic table illustration shows the correct trend for the 1stionization energy (IE)?

A.

✓B.

C.

D.

Question #: 26

The ionization energies (in kJ/mol) of a second period element are given below.  Which element

is it?

IE1 = 899    IE2 = 1757    IE3 = 14850    IE4 = 21005

.

A. Li

✓B. Be C. B D. C E. N

Question #: 27

Electron affinity is the energy associated with which reaction?

✓A. X(g) +e– →X–(g)

B. X(g) →X+(g) + e–

C. X–(g) →X(g) + e–

D. X+(g) + e– →X(g)

Question #: 28

Which option lists the elements in order of increasing metallic character?

A. Ba <K <Mg <Na

B. K <Mg <Na <Ba C. Ba <K <Mg <Na

✓D. Na <Mg <K <Ba

Question #: 29

What is the electron configuration of the most common aluminumcation?

✓A. [Ne] B. [Ne]3s2

C. [Ne]3s23p1

D. [Ne]3s1

E. [Ne]3s23p6

Question #: 30

Select the two answers which correctly complete the statement: "Ionic bonds form ___"

✓A. between a metal and a non-metal.

B. between two non-metals. C. between two metals.

✓D. due to electrostatic attractions as a result of electron transfer. E. when electrons are shared between atoms.