CHEM 1100 Exam 2 Name __________________________________
Dr. Byrd
10/25/06

Some useful constants: R = 1.097 x 10^-2 nm^-1; h = 6.626 x 10^-34 J^.s; c = 2.997 x 10⁸ m^.s^-1

Part 1. Note: For Part 1 you must show your work to receive credit for a problem. Include units and pay attention to significant figures. This part is worth a total of 55 points.
1)	(12) A sample of a compound containing only the elements carbon, hydrogen, and oxygen was analyzed by combustion and found to contain the following percentages of each of the elements: 49.31 % C 6.90 % H 43.79 % O a) (8) Determine the empirical formula of the compound. b) (4) In a separate experiment using a mass spectrometer, the molar mass of the compound was determined to be 146 g/mol. What is the molecular formula of the compound?

2)

(10) Complete and balance the following reactions as directed below. If there is no reaction, write "no reaction." a) net ionic reaction in aqueous solution nitric acid + potassium hydroxide → b) overall equation in aqueous solution sulfuric acid + sodium hydroxide → c) overall reaction in aqueous solution KBr + Pb(NO3)2 → d) overall reaction in aqueous solution Ca(NO 3)2(aq) + NaCl(aq) → e) In the rectangles below write the formulas of two compounds which would react in water to form silver(I) iodide.

3)

(11) Write the complete, balanced, net ionic equation for the reaction shown below in basic solution. Cl2(aq) + V2+(aq) → Cl-(aq) + VO+2(aq)

4)

(11) A 50.00 mL sample of nitric acid required 40.18 mL of 0.1005 M sodium hydroxide in a titration. Calculate the concentration of the nitric acid solution.

5)

a) (7) Calculate the wavelength of the light emitted when an electron in an excited hydrogen atom drops from an n = 4 level to an m = 3 level. b) (4) Calculate the energy of this light (in joules).

Part 2. MULTIPLE CHOICE -- 15 questions. 3 points each. Choose the one alternative that best completes the statement or answers the question.
Box (1) represents 1.0 mL of a solution of particles at a given concentration.
6)	Which of the boxes (2)-(5) represents 1.0 mL of the solution that results after (1) has been diluted by adding enough solvent to make 2.0 mL of solution?	6) ______

	A)  box (4)
	B)  box (5)
	C)  box (3)
	D)  box (2)

7)

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

7) ______

	A)  C2H4
	B)  C2H
	C)  C4H4
	D)  CH

8)

What is the molar concentration of sodium ions in a 0.150 M potassium sulfate solution?

8) ______

	A)  0.450 M
	B)  0.300 M
	C)  0.150 M
	D)  0.075 M
	E)  0.600 M

9)

Which statement about elemental analysis by combustion is not correct?

9) ______

	A)  Oxygen is determined from the amount of H2O formed.
	B)  Only carbon and hydrogen can be determined directly from CO2 and H2O.
	C)  Carbon is determined from the amount of CO2 formed.
	D)  Hydrogen is determined from the amount of H2O formed.
	E)  None of the above.

10)

Molarity is defined as

10) ______

	A)  moles of solvent per liter of solution.
	B)  moles of solute per liter of solution.
	C)  moles of solvent per liter of solvent.
	D)  moles of solute per liter of solvent.
	E)  moles of solute per kilogram of solvent.

11)

Which pair of compounds is soluble in water?

11) ______

	A)  potassium iodide and barium nitrate
	B)  silver bromide and silver iodide
	C)  cadmium silfide and ammonium sulfide
	D)  sodium nitrate and calcium carbonate
	E)  None of the above

12)

Which pair of reactants will produce a precipitate when mixed together?

12) ______

	A)  HI(aq) and Na2CO3(aq)
	B)  HI(aq) and NaOH(aq)
	C)  HI(aq) and Na2S(aq)
	D)  HI(aq) and Pb(NO3)2(aq)
	E)  None of the above

13)

Using the following portion of the activity series for oxidation half reactions K(s) → K+(aq) + e- Al(s) → Al3+(aq) + 3e- Fe(s) → Fe2+(aq) + 2e- Sn(s) → Sn2+(aq) + 2e- determine which reaction will occur.

13) ______

	A)  K+(aq) with Fe2+(aq)
	B)  Al(s) with Sn(s)
	C)  K(s) with Sn2+(aq)
	D)  Al3+(aq) with Fe(s)

14)

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

14) ______

	A)  Zn(s)
	B)  + Cu2+(aq)
	C)  Cu(s)
	D)  Zn2+(aq)

15)

The greater the energy of a photon, the

15) ______

	A)  shorter the wavelength and the higher the frequency.
	B)  shorter the wavelength and the lower the frequency.
	C)  longer the wavelength and the lower the frequency.
	D)  longer the wavelength and the higher the frequency.
	E)  None of the above.

16)

Of the following, which has the shortest de Broglie wavelength?

16) ______

	A)  a helium nucleus moving at a velocity of 1000 mph
	B)  a nitrogen molecule moving at a velocity of 5000 mph
	C)  a nitrogen molecule moving at a velocity of 1000 mph
	D)  an airplane moving at a velocity of 300 mph
	E)  None of the above.

17)

According to the Heisenberg uncertainty principle,

17) ______

	A)  the position and momentum of a particle can be measured precisely, but not at the same time.
	B)  the position of a particle cannot be measured precisely.
	C)  the momentum of a particle cannot be measured precisely.
	D)  neither the position nor the momentum of a particle can be measured precisely.
	E)  None of the above.

18)

What are the possible values of n and ml for an electron in a 5d orbital?

18) ______

	A)  n = 1, 2, 3, 4, or 5 and ml = -2, -1, 0, +1, or +2
	B)  n = 5 and ml = 2
	C)  n = 5 and ml = -2, -1, 0, +1, or +2
	D)  n = 1, 2, 3, 4, or 5 and ml = 2
	E)  None of the above.

19)

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

19) ______

	A)  larger the average distance from the nucleus and the lower the orbital energy.
	B)  larger the average distance from the nucleus and the higher the orbital energy.
	C)  smaller the average distance from the nucleus and the lower the orbital energy.
	D)  smaller the average distance from the nucleus and the higher the orbital energy.
	E)  None of the above.

20)

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

20) ______

	A)  n = 4 and l = 1
	B)  n = 4 and l = 0
	C)  n = 3 and l = 4
	D)  n = 4 and l = 3
	E)  n = 4 and l = -1