Chem 1100 Final Exam  Fall 2003  Dr. Byrd

 

MULTIPLE CHOICE.  Choose the answer that best completes the statement or answers the

question.  50 questions, 110 points.

1)  Lithium belongs to the ________ group of the periodic table.

A) noble gas

B) alkaline earth metal

C) alkali metal

D) halogen

E) none of the above

 

2)  The freezing point of methane is -184°C and the boiling point is -161°C. The temperature of the surface of Titan, a moon of Saturn, is 93 K. If methane exists on Titan, it is

A) a liquid.

B) a plasma.

C) a solid.

D) a gas.

E) none of the above

 

3)  How many significant figures are there in the answer for the following problem?

(131.7 – 119)/0.50 = ?

A) one

B) two

C) three

D) four

E) none of the above

 

4)  To the correct number of significant figures, what is the volume of the liquid in the graduated cylinder?

 

 

A) 7.7 mL

B) 8 mL

C) 7 mL

D) 7.0 mL

E) none of the above

 

5)  What is the chemical symbol for an atom that has 29 protons and 36 neutrons?

A) Kr B)  Zn C)  Tb D)  N E)  Cu

 

6)  When dissolved in water, of HClO_4, Ca(OH)₂, KOH, HI, which are acids?  

A) HClO₄ and HI

B) Ca(OH)₂ and KOH

C) only HI

D) only KOH

E) all of them

 

7)  Li₂SO₄ is named

A) lithium sulfide.

B) dilithium disulfite.

C) lithium(II) sulfate.

D) lithium sulfate.

E) lithium sulfite.

 

8)  What is the chemical formula for iron(II) phosphate?

A) Fe₃P₂

B) Fe₃(PO₄)₂

C) Fe₂PO₄

D) Fe₂P

E) none of the above

 

9)  The ion NO^3- is named

A) nitrate ion.

B) nitrogen(III) oxide ion.

C) nitrite ion.

D) nitrogen trioxide ion.

E) none of the above

 

10)  What is the molar mass of aspartic acid, C₄O₄H₇N?

A) 197 g/mol

B) 70 g/mol

C) 43 g/mol

D) 133 g/mol

E) none of the above

 

11)  Molarity is defined as

A) moles of solvent per liter of solution.

B) moles of solute per liter of solvent.

C) moles of solute per liter of solution.

D) moles of solvent per liter of solvent.

E) liters of solute per mole of solvent

 

12)  What is the concentration of HCl in the final solution when 65 mL of a 12 M HCl solution is diluted with pure water to a total volume of 0.15 L?

A) 5.2 M B)  5.2 þ 10³ M

C) 28 M D)  2.8 þ 10^-2 M

 

13)  In an acid-base neutralization reaction 23.74 mL of 0.500 M potassium hydroxide reacts with 50.00 mL of hydrochloric acid solution. What is the concentration of the H₂SO₄ solution?

A) 0.119 M

B) 0.237 M

C) 2.11 M

D) 0.475 M

E) none of the above

 

14)  Which of the following statements is true concerning the formula of a compound?

A) The empirical formula is the simplest whole numbered ratio of atoms in a compound.

B) The number of atoms in a molecular formula is always greater than the number of atoms in an empirical formula.

C) The molecular formula is the true ratio of atoms in a compound.

D) The molecular formula and empirical formula can be identical.

E) A, C and D

 

15)  A hydrocarbon of unknown formula C_xH_y was submitted to combustion analysis with the following results. What is the empirical formula of the hydrocarbon?

 

 

A) C₅H₂ B)  C₁₀H₈ C)  C₅H₄ D)  C₁₀H₄ E)  CH

 

16)  The reaction of Cu(s) + 2 AgNO₃(aq) Â Cu(NO₃)₂(aq) + 2 Ag(s) is best classified as a(n)

A) acid-base neutralization reaction.

B) precipitation reaction.

C) oxidation-reduction reaction.

D) double replacement reaction.

E) none of the above.

 

17)  The mixing of which pair of reactants will result in a precipitation reaction?

A) NaClO₄(aq) + (NH₄)₂S(aq)

B) NH₄Br(aq) + NaI(aq)

C) Cu(NO₃)₂(aq) + Na₂CO₃(aq)

D) KCl(aq) + Cu(NO₃)₂(aq)

E) all of them

 

18)  Write a net ionic equation for the neutralization reaction of HCl(aq) with NaOH(aq).

A) HCl(aq) + Na⁺(aq) + OH^-(aq) Â Na⁺(aq) + Cl^-(aq) + H₂O(l)

B) HCl(aq) + OH^-(aq) Â Cl^-(aq) + H₂O(l)

C) HCl(aq) + NaOH(aq) Â NaCl(aq) + H₂O(l)

D) H₃O⁺(aq) + OH^-(aq) Â 2H₂O(l)

E) none of the above

 

19)  Which species functions as the oxidizing agent in the following reduction-oxidation reaction:

Zn(s) + Cu2+(aq) Â Cu(s) + Zn²⁺(aq)

 

A) Zn²⁺(aq)

B) Zn(s)

C) Cu(s)

D) Cu²⁺(aq)

E) Cu(s) and Zn(s)

 

20)  Using the following portion of the activity series for oxidation half reactions

K(s) Â K⁺(aq) + e^-

Al(s) Â Al³⁺(aq) + 3e^-

Fe(s) Â Fe²⁺(aq) + 2e^-

Sn(s) Â Sn²⁺(aq) + 2e^-

determine which reaction will occur.

A) Al(s) with Sn(s)

B) K⁺(aq) with Fe²⁺(aq)

C) Al³⁺(aq) with Fe(s)

D) K(s) with Sn²⁺(aq)

E) all of them can occur

 

21)  The greater the energy of a photon, the

A) shorter the wavelength and the higher the frequency.

B) longer the wavelength and the higher the frequency.

C) shorter the wavelength and the lower the frequency.

D) longer the wavelength and the lower the frequency.

E) the smaller the photon

 

22)  For an electron in a given atom, the larger n, the

A) larger the average distance from the nucleus and the lower the orbital energy.

B) smaller the average distance from the nucleus and the higher the orbital energy.

C) larger the average distance from the nucleus and the higher the orbital energy.

D) smaller the average distance from the nucleus and the lower the orbital energy.

E) the smaller the electron.

 

23)  Which of the following is not a valid set of quantum numbers?

A) n = 3, l = 0, m_l = 0, and m_s = 1/2

B) n = 3, l = 2, m_l = 3, and m_s = 1/2

C) n = 2, l = 1, m_l = -1, and m_s = -1/2

D) n = 2, l = 1, m_l = 0, and m_s = -1/2

E) all of them are valid

 

24)  For the fourth-shell orbital shown below, what are the principal quantum number, n, and the angular momentum quantum number, l?

 

 

A) n = 4 and l = 0

B) n = 4 and l = 1

C) n = 4 and l = 2

D) n = 4 and l = 3

E) n = 4 and l = 4

 

25)  Atoms of which element, indicated by letter on the periodic table, have the orbital-filling diagram shown below?

 

 

A) A

B) B

C) C

D) D

E) none of the above

 

26)  For a multielectron atom, a 3s orbital lies lower in energy than a 3p orbital because

A) other electrons more effectively shield electrons in the 3s orbital from the nucleus.

B) other electrons more effectively shield electrons in the 3p orbital from the nucleus.

C) there are more p orbitals than s orbitals in a given shell.

D) a 3p orbital has more nodal surfaces than a 3s orbital.

E) none of the above.

 

27)  How many valence electrons does a neutral chlorine atom have?  

A) 1

B) 17

C) 7

D) 5

E) none of the above

 

28)  Of the following, which atom has the smallest atomic radius?

A) S B)  Si C)  Mg D)  Se E)  Xe

 

29)  What is the ground-state electron configuration of antimony (Sb)?

A)  [Kr]5s²5p³

B)  [Kr]4f¹⁴4d¹⁰5s²5p³

C)  [Kr]5s²5p⁶5d⁷

D)  [Kr]4d¹⁰5s²5p³

E) none of the above

 

30)  What is the ground-state electron configuration of the ion Hg²⁺?

A) [Xe]4f¹⁴5d¹⁰6s²6p²

B) [Xe]4f¹⁴5d¹⁰6s²

C) [Xe]4f¹⁴5d⁸6s²

D) [Xe]4f¹⁴5d¹⁰

E) none of the above

 

31)  Of the following, which element has the highest first ionization energy?

A) Cl B)  Na C)  Ca D)  Se E)  K

 

32)  Which of the following ionic compounds would be expected to have the highest lattice energy?

A) NaCl

B) RbCl

C) LiCl

D) KCl

E) they will all be the same

 

33)  The electronegativity for both sulfur and carbon is 2.5. Therefore the compound CS₂ would be expected to

A) be ionic with C as the anion.

B) be ionic with C as the cation.

C) have polar covalent bonds between C and S.

D) have nonpolar covalent bonds between C and S.

E) be ionic with S as the cation.

 

34)  How many lone pairs of electrons are on the P atom in PF₃?

A) 0 B)  1 C)  2 D)  3 E)  4

 

35)  Consider a molecule with the following connections:

 

 

When a valid electron dot structure is written, how many double bonds will the molecule contain?

A) 0 B)  1 C)  2 D)  3 E)  4

 

36)  Identify the set of hybrid orbitals shown below.

 

 

A) sp B)  sp² C)  sp³ D)  sp^3d E)  sp^3d2

 

37)  Which drawing represents a s bonding molecular orbital for a homonuclear diatomic molecule?

A)

 

B)

 

C)

 

D)

 

E) none of the above

 

38)  For a process at constant pressure,

A) DE = w and q = 0.

B) DH = q.

C) DE = q and w = 0.

D) DE = DH.

E) none of the above

 

39)            Given:   

S (s) + O₂ (g) Â SO₂ (g)                                 DH° = -296.1 kJ

        2 SO₃ (g) Â 2 SO₂ (g) + O₂ (g)                      DH° = 198.2 kJ

Find DH° for : 2 S(s) + 3 O₂(g) Â 2 SO₃(g)

A) -790.4 kJ

B) -97.9 kJ

C) -394.0 kJ

D) +97.9 kJ

E) none of the above

 

40)  Which equation represents the reaction whose DH, represents the standard enthalpy of formation of CHCl₃(l) at 25°C? (i.e., for which  is DH = DH°_f  of CHCl₃)

A) CHCl₃(l) Â C(s) + H(g) + 3 Cl(g)

B) C(s) + H(g) + 3 Cl(g) Â CHCl₃(l)

C) 2 C(s) + H₂(g) + 3 Cl₂(g) Â 2 CHCl₃(l)

D) C(s) + 1/2 H₂(g) + 3/2 Cl₂(g) Â CHCl₃(l)

E) none of the above

 

 

42)  Determine the sign of DS° for each of the following processes:

I.     C₆H₆(s) Â C₆H₆(l)

II.     2 SO₂(g) + O₂(g) Â 2 SO₃(g)

A) DS° should be negative for I and positive for II.

B) DS° should be negative for I and negative for II.

C) DS° should be positive for I and negative for II.

D) DS° should be positive for I and positive for II.

 

43)  Which combination always results in a process being spontaneous?

A) DH is positive and DS is positive.

B) DH is positive and DS is negative.

C) DH is negative and DS is positive.

D) DH is negative and DS is negative.

E) there are no guaranties in this universe.

 

44)  The pressure in the eye of a hurricane is less than one atmosphere. Which one of the following pressure readings could not have been taken in the eye of a hurricane?

A) 690 mm Hg

B) 9.22 þ 10⁴ Pa

C) 15 lbs/in²

D) 65 cm Hg

E) they all look just fine to me

 

45)  An approximation of absolute zero was made from an extrapolation of

A) V vs. 1/T

B) V vs. T

C) n vs. V

D) P vs. 1/V

E) all of these

 

46)  A basketball is inflated to a pressure of 1.50 atm in a 20.0eC garage. What is the pressure of the basketball outside where the temperature is -5.00°C?

A) 1.42 atm

B) 1.58 atm

C) 1.37 atm

D) 1.64 atm

E) the value of the volume of the garage is required

 

47)  Three identical flasks contain three different gases at standard temperature and pressure. Flask A contains CH₄, flask B contains CO₂, flask C contains N₂. Which flask contains the largest number of molecules?

A) flask A

B) flask B

C) flask C

D) flask D

E) All of the flasks contain the same number of molecules.

 

48)  Which of the following gases has the highest average speed at 400K?

A) N₂O₄

B) UF₆

C) SF₆

D) CO₂

E) all of the gases have the same average speed

 

49)  Which one of the following gases will have the highest rate of effusion?

A) NO₃ B)  NO₂ C)  N₂O D)  N₂O₄

 

50)  An unknown gas effuses 1.73 times faster than krypton. What is the molar mass of the gas?

A) 110 g/mol

B) 251 g/mol

C) 48.4 g/mol

D) 28.0 g/mol

E) only Superman can answer this

 

Part II.  Six problems/15 points each = 90 total.  Do only 6 of the 7 questions.  Put a big X across the one you don't want graded.   In all of these problems, be sure to show your work to receive credit.  Don't forget units and significant figures.

 

 

1(15)  A 1.000 g sample of a gaseous hydrocarbon containing only carbon and hydrogen was

  analyzed by combustion forming 3.035 g of CO₂(g) and 1.553 g of H₂O(l).        

 

 

(10) Determine the empirical formula of the compound.

 

 

 

 

 

(5)  A separate measurement using the density of the gas gave a molar mass of 87 g/mol.  Determine the molecular formula of the compound.

 

2(15)  Sodium peroxide is used to remove carbon dioxide gas from the air in spacecraft  according to the unbalanced reaction

 

 Na₂O₂(s)  +   CO₂(g)        Na₂CO₃(s)   +  O₂(g)

 

a) (3)  Balance the reaction.

 

 

b) (6)  Determine the mass of sodium peroxide needed to remove 5.555 kg of carbon dioxide from a spacecraft.

 

 

 

 

 

 

c) (6)  How many kilograms of O₂(g) would be formed?

 

 

3(8)  Choose two ionic compounds which could be used to prepare solid iron(III) carbonate by a precipitation reaction from mixing their aqueous solutions.  Write the formulas for your

compounds.

 

 

 

 

(7)   Write the balanced net ionic equation for the reaction which will occur when the solutions

 are mixed.

 

 

 

 

4(15) Calculate the lattice energy for MgF₂(s) using a Born-Haber cycle and the following information:

 

MgF₂(s)     Mg⁺²(g) + 2F^-(g)                                 ?

Mg(s)  + F₂(g)    MgF₂(s)                                       -790 kJ/mol

Mg(s)     Mg(g)                                                        +147 kJ/mol

F₂(g)     2F(g)                                                          +159 kJ/mol

Mg(g)     Mg⁺¹(g)  + e^-                                                         +738 kJ/mol

Mg⁺¹(g)    Mg⁺²(g)  + e^-                                                      +1451 kJ/mol

F(g)  + e^{-  Â}  F^-(g)                                                     -328 kJ/mol

 

 

 

 

 

5)  (5)  a) In the space below write the electron dot structure for the ion BrF₄^-1 .

 

 

 

 

 

 

 

 

 

 

b) (2) How many charge clouds are on the central atom?

               0                 1         2            3             4             5             6             7

 

 

c) (2) How many lone pairs are on the central atom?

               0                 1                        2             3             4             5             6             7

 

 

d) (2) What is the hybridization on the central atom?

                             

               sp           sp²             sp³             sp³d        sp³d²        sp³d³

 

e) (2)  What is the shape or geometry of the structure of the ion?

 

 

 

 

 

 

 

f) (2)  Is it polar or nonpolar?

 

 

 

6)  (15)  Use the data in the table below to determine DH° , DS° and DG° at  25.0 °C for the reaction in problem 2.

                         DH°_f (kJ/mol)      S°(J/mol ^.K)

Na₂O₂(s)           -510.9                      95.0

CO₂(g)               -393.5                    213.6

Na₂CO₃             -1130.7                 135.0

O₂(g)                     0                          205.0

 

 

 

 

 

 

 

 

(3) Is the reaction spontaneous at 25.0°C?  Explain briefly.

 

 

 

 

 

(3) If the temperature in the spacecraft were to change, is it possible for the reaction to be non-spontaneous as it is written and thus for the oxygen to be converted to carbon dioxide?  Explain briefly.

 

 

 

7(8)  If 2.019 kg of oxygen were to be formed in the reaction shown in problem 2, what would the volume of the oxygen be at 22.5 °C  and 755 mm Hg pressure?

 

note:  R = 0.0821 L^.atm/mol^.K;  1.000 atm = 760 mm Hg

 

 

 

 

 

(7) What volume of carbon dioxide would be removed at this temperature and pressure?