CHEM 1100 Print Name___________________________________
Dr. Byrd
11/29/06 Exam 3

Part I. (52 points total) Please answer all of the questions. Pay attention to units and significant figures.
1)	Use the following data to calculate the value of the lattice energy of beryllium chloride. a) (5) Write the balanced chemical reaction which corresponds to the lattice energy of beryllium chloride. b) (12) Calculate the lattice energy here.

2)

a) (3) In the space below, write the electron dot structure for the compound ClF3. Include all resonance forms if appropriate. (How many valence electrons?) → b) (3) How many charge clouds are on the central atom? 0 1 2 3 4 5 6 c) (3) How many lone pairs are on the central atom? 0 1 2 3 4 5 6 d) (3) What is the hybridizaiton on the central atom? sp sp2 sp3 sp3d sp3d2 sp3d3 e) (3) What is the shape or geometry of this ion? Draw the shape. → f) (3) Is it polar or nonpolar?

3)

A sample of an unknown metal with a mass of 81.15 g was heated to 100.0 °C in a beaker of boiling water. It was then carefully placed in a styrofoam cup containing 2.00 x 102 g of water with a temperature of 25.0 °C. The water temperature rose to 29.3 °C. (Note: The specific heat capacity of water is 4.18 J/g.°C.) a) (8) Calculate the amount of heat gained by the water. b) (9) Calculate the specific heat capacity of the metal.

Part II. (48 points total) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
4)	What is the ground-state electron configuration of the ion Tl1+?	4) ______

	A)  [Xe]4f145d106s2
	B)  [Xe]4f145d10
	C)  [Xe]4f145d106s26p1
	D)  [Xe]4f145d96s2
	E)  None of the above.

5)

Which two ions have the same electron configuration in the ground state?

5) ______

	A)  Fe2+ and Fe3+
	B)  Ba2+ and I-
	C)  Rb+ and Cs+
	D)  Se2+ and I-
	E)  None of the above.

6)

Indicate which is larger in each of the following two sets. (I) Cr3+ or Cr (II) Se2- or Se

6) ______

	A)  Cr3+ is larger than Cr and Se2- is larger than Se.
	B)  Cr is larger than Cr3+ and Se is larger than Se2-.
	C)  Cr is larger than Cr3+ and Se2- is larger than Se.
	D)  Cr3+ is larger than Cr and Se is larger than Se2-.

7)

List the elements Na, Ca, Rb, Cl, He in order of increasing first ionization energy.

7) ______

	A)  He > Na > Cl > Ca > Rb
	B)  Rb > Ca > Cl > Na > He
	C)  He > Cl > Ca > Na > Rb
	D)  He > Na > Ca > Cl > Rb
	E)  None of the above.

8)

What is the general trend in ionization energy and electron affinity values?

8) ______

	A)  Both decrease as one traverses a period from left to right and both decrease as one descends a group.
	B)  Both increase as one traverses a period from left to right and both increase as one descends a group.
	C)  Both decrease as one traverses a period from left to right and both increase as one descends a group.
	D)  Both increase as one traverses a period from left to right and both decrease as one descends a group.
	E)  None of the above.

9)

Which ionic compound would be expected to have the highest lattice energy?

9) ______

	A)  Al2O3
	B)  AlF3
	C)  NaCl
	D)  MgO
	E)  They are all the same.

10)

Which electrostatic forces hold atoms together in a molecule?

10) ______

	A)  electron-nucleus forces
	B)  electron-electron forces
	C)  nucleus-nucleus forces
	D)  All three forces
	E)  None of these forces are correct.

11)

Which bond should have the highest bond dissociation energy?

11) ______

	A)  NN
	B)  NN
	C)  NN
	D)  All three bonds should have about the same dissociation energy.

12)

In general, at room temperature

12) ______

	A)  ionic compounds are all solids and covalent compounds are all gases.
	B)  covalent compounds are all gases, but ionic compounds may be solids, liquids, or gases.
	C)  ionic compounds are all solids, and covalent compounds are liquids or gases.
	D)  ionic compounds are all solids, but covalent compounds may be solids, liquids, or gases.
	E)  all compunds can be solids, liquids or gases.

13)

Of the following elements, which has the highest electronegativity?

13) ______

	A)  S
	B)  Sc
	C)  P
	D)  As

14)

The greater the electronegativity difference between two bonded atoms, the

14) ______

	A)  greater the bond order.
	B)  greater the covalent character of the bond.
	C)  shorter the bond.
	D)  more unstable the bond.
	E)  greater the ionic character of the bond.

15)

The compound ICl contains

15) ______

	A)  polar covalent bonds, with partial negative charges on the Cl atoms.
	B)  polar covalent bonds, with partial negative charges on the I atoms.
	C)  nonpolar covalent bonds.
	D)  ionic bonds.
	E)  None of the above.

16)

Which electron dot structure for OCN- has a formal charge of -1 on the most electronegative atom?

16) ______

	A)
	B)
	C)
	D)
	E)  None of the above.

17)

What geometric arrangement of charge clouds is expected for an atom that has five charge clouds?

17) ______

	A)  octahedral
	B)  square planar
	C)  trigonal planar
	D)  tetrahedral
	E)  trigonal bipyramidal

18)

The orbital hybridization on the carbon atom in HCN is

18) ______

	A)  sp3.
	B)  sp2.
	C)  sp3d
	D)  sp3d2.
	E)  sp

19)

The MO diagram below is appropriate for B2. (Note: put in ALL of the electrons) Based on this diagram, B2

19) ______

	A)  has a bond order of two and is paramagnetic.
	B)  has a bond order of two and is diamagnetic.
	C)  has a bond order of one and is diamagnetic.
	D)  has a bond order of three and is paramagnetic.
	E)  has a bond order of one and is paramagnetic

20)

Identify the set of hybrid orbitals shown below.

20) ______

	A)  sp
	B)  sp2
	C)  sp3
	D)  sp3d
	E)  sp3d2

21)

For a process at constant volume,

21) ______

	A)  q = 0, w = 0, and ΔE = 0.
	B)  w = 0 and ΔE = q.
	C)  w = 0 and ΔE = ΔH.
	D)  w = 0 and ΔH = q.
	E)  None of the above.

22)

For a process at constant pressure,

22) ______

	A)  ΔE = ΔH.
	B)  ΔH = q.
	C)  ΔE = w and q = 0.
	D)  ΔE = q and w = 0.
	E)  None of the above.

23)

In which case is the work done on the system positive?

23) ______

	A)  ΔV > 0
	B)  ΔV < 0
	C)  ΔV = 0
	D)  ΔE > 0
	E)  ΔH > 0

24)

Calculate the work, w, done on the surroundings when a gas expands from 15 L to 35 L against a constant external pressure of 1.5 atm. [1 L ∙ atm = 101 J]

24) ______

	A)  +5.3 kJ
	B)  -5.3 kJ
	C)  +3.0 kJ
	D)  -3.0 kJ

25)

Most chemical reactions are carried out in one of two ways: I. in an open vessel at constant atmospheric pressure II. in a closed vessel Which is true?

25) ______

	A)  ΔH = w for condition I and ΔE = w for condition II
	B)  ΔH = q for condition I and ΔE = q for condition II
	C)  ΔE = q for condition I and ΔH = q for condition II
	D)  ΔE = w for condition I and ΔH = w for condition II

26)

A process is carried out at constant pressure. Given that ΔE is positive and ΔH is negative,

26) ______

	A)  the system loses heat and expands during the process.
	B)  the system loses heat and contracts during the process.
	C)  the system absorbs heat and expands during the process.
	D)  the system absorbs heat and contracts during the process.

27)

Imagine a reaction that results in a change in both volume and temperature, as shown in the diagram below. What is the sign of the work being done and the sign of the enthalpy change involved in this reaction?

27) ______

	A)  w = + and ΔH = -
	B)  w = - and ΔH = +
	C)  w = + and ΔH = +
	D)  w = - and ΔH = -