Final Exam--S/98

Chemistry 122S
Summer 1998
Oregon State University
Final Exam
August 13, 1998
Dr. Richard Nafshun

Name __________________________________________ Score ___________ / 160

Possibly useful information:

 [Periodic Table Here]

Give Lewis Symbols for Atoms, Molecules, Ions, and Polyatomic Ions--5 Points

1. Give the Lewis Symbol for NH₂OH (please include all electrons).

Using Formal Charges, Predict Stable Lewis Structures--10 Points

2. Draw ONE REASONABLE Lewis Symbol for phosgene, COCl₂. Determine the formal charges for each element in the molecule and comment on the stability of the structure.

 

Discuss Polymers--5 Points

3. Which of the following molecules can undergo polymerization in the presence of an initiator?

(a) C₂F₄.

(b) C₂H₂F₄.

(c) C₂H₂Cl₄.

(d) C₃H₂F₂Cl₂.

(e) C₃H₇F.

 

Predict Molecular Shapes (Molecular Geometries and Bond Angles)--5 Points

4. The H-P-H bond angle in phosphane, PH₃, is

(a) 90° .

(b) A little less than 109.5° .

(c) Exactly 109.5° .

(d) A little more than 109.5° .

(e) Exactly 120° .

Discuss Polar and Non-Polar Molecules--5 Points

5. An example of a non-polar molecule is __________________.

An example of a polar molecule is ______________________.

Create and Interpret MO Energy Diagrams--5 Points

6. Consider Ne₂ (g). Create a MO energy diagram, fill-in the electrons, and determine the bond order for neon-neon bond.

Construct and Interpret Resonance Structures--5 Points

7. Nitrogen is the central atom in the nitrate ion, NO₃^-. Draw three resonance structures for the nitrate ion and indicate the bond order for the nitrogen to oxygen bond.

Calculate the Pressure, Volume, Number of Moles, Molecular Mass, or Temperature

of an Ideal Gas--10 Points Each

8. A student fills a 3.000 liter vessel with 2.324 grams of an ideal, unknown gas at 24.45 ° C and measures the pressure to be 0.6756 atm. Calculate the molar mass of the gas.

9. A student places 0.04981 moles of ideally behaved helium in a 3.000 liter Thermos bottle at 23.55 ° C. She then cools the bottle to -98 ° C. Calculate the pressure inside the bottle at -98 ° C.

Determine the Volume of a Gas Produced in a Limiting Reagent Problem--10 Points

10. A student places 6.755 g of magnesium into 25.00 ml of 2.500 M HCl to produce hydrogen gas and magnesium chloride at 25.32 ° C and 1.200 atm. How many liters of hydrogen gas are produced?

Discuss Relative Rates of Effusion--5 Points

11. Which of the following ideal gases has the greatest u_rms at STP?

(a) Ar.

(b) C₃H₈.

(c) CH₃OCH₃.

(d) CH₃CH₂OH.

(e) CO.

Predict, Based on Intermolecular Forces, Physical Properties of Atoms and Molecules--5 Points

12. Based on intermolecular forces, predict which of the following six molecules has the highest boiling point. [Circle your final answer.]

CH₃OCH₃ CH₃CH₂OH CH₃CH₂F CH₃CH₃ CH₂CH₂ HCCH

Objective: Identify Strong, Weak, and Non Electrolytes--5 Problems, 2 Points Each

For problems 13-17, circle or box the correct the best description.

For example,

Sucrose is a: strong-electrolyte weak-electrolyte non-electrolyte.

13. CaCl₂ is a: strong-electrolyte weak-electrolyte non-electrolyte.

14. HCl is a: strong-electrolyte weak-electrolyte non-electrolyte.

15. CF₄ is a: strong-electrolyte weak-electrolyte non-electrolyte.

16. HCOOH is a: strong-electrolyte weak-electrolyte non-electrolyte.

17. CH₃OH is a: strong-electrolyte weak-electrolyte non-electrolyte.

Objective: Determine Oxidation Numbers--5 Points Each

18. The oxidation number (oxidation state) of Pt in PtF₆ is _____________.

(Include the sign)

19. The oxidation number (oxidation state) of Ca in CaCO₃ is _____________.

(Include the sign)

Objective: Discuss Redox Reactions--5 Problems, 2 Points Each

Problems 20-24 refer to the following balanced reaction:

SnCl₂ (aq) + 2 FeCl₃ (aq) ------> SnCl₄ (aq) + 2 FeCl₂ (aq)

20. The reducing agent is _____________________________.

21. The oxidizing agent is _____________________________.

22. The species being reduced is _____________________________.

23. The species being oxidized is _____________________________.

24. The species gaining electrons is _____________________________.

Objective: Calculate the Concentration of a Reagent Based on Titration Data--5 Points

25. A student titrated 25.00 mL of an HCl solution of unknown concentration. He added 31.75 mL of 0.1872 M sodium hydroxide to reach the equivalence point. Determine the concentration of the HCl solution.

 

 

Objective: Calculate the Freezing Point Depression--5 Points

26. A student places 2975 grams of sucrose, C₁₂H₂₂O₁₁ (FW = 342.3), in 5.500 kg of water. Calculate the freezing point of the solution.

Objective: Identify the Properties of Each Atmospheric Layer--10 Points

27. Discuss the change of temperature as a function of elevation within the troposphere.

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Objective: Calculate the Relative Humidity--5 Points

28. The partial pressure of water vapor in an air sample at 20.0 ° C is found to be 8.26 mmHg. The vapor pressure of water at 20.0 ° C is 17.5 mmHg. Calculate the relative humidity of this air.

Objective: Discuss the Properties of Nitrogen and its Compounds--5 Points

29. Discuss the reactivity of nitrogen and nitrogen containing compounds with foliage.

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Objective: Discuss the Properties of Oxygen and its Compounds--5 Points

30. Discuss the reactivity of oxygen with copper, silver, and gold.

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Objective: Discuss the Reactivity of EDTA--5 Points

31. Discuss the reactivity of EDTA with calcium ion.

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Objective: Discuss the Effects of Carbon Monoxide--10 Points

32. Discuss the effects of carbon monoxide on humans.

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