CH 201 Fall 2004
Final Exam Key
**Note: Exam scores, CSB scores, and course grades will be posted on Monday morning!
1. Which of the following statements about the element chlorine is incorrect?
a) Chlorine is a metal that forms a 2+ cation. Its symbol is Cl.
b) Chlorine can form covalent bonds.
c) Chlorine is a halogen.
d) Chlorine has 7 valence electrons.
e) Chlorine occurs naturally as a diatomic gas.
2. What is the correct name for the compound Fe2O3?
a) fluorine oxide
b) iron (III) oxide
c) iron(II) oxide
d) phosphate oxide
e) diflourine trioxide
3. Which of the following statements about atomic structure is incorrect?
a) Protons and neutrons are located within the nucleus of an atom.
b) For a single element, the number of electrons can vary to give ions.
c) For a single element, the number of neutrons can vary to give isotopes.
d) For a neutral atom, the number of protons and neutrons must be equal.
e) As atomic numbers in the periodic table increase, the number of protons in each element increases.
4. The symbol 85Sr 2+ represents an atom with
a) 38 protons, 47 neutrons, and 40 electrons
b) 85 protons, 38 neutrons, and 83 electrons
c) 47 protons, 38 neutrons, and 49 electrons
d) 85 protons, 38 neutrons, and 40 electrons
e) 38 protons, 47 neutrons, and 36 electrons
5. Which of the following compounds is 22.2% nitrogen by mass?
a) sodium hydroxide
b) ammonia
c) water
d) nitric acid
6. Ammonia can be prepared by the reaction shown below. How many grams of nitric acid are expect to react with 10.0 g of hydrogen gas?
HNO3(g) + 4 H2(g) à NH3(g) + 3 H2O(g)
a) 40.0 g of HNO3
b) 2.50 g of HNO3
c) 78.8 g of HNO3
d) 315 g of HNO3
7. The unbalanced reaction for the combustion of methane is shown below. 7.0 moles of methane are combined with 12 moles of oxygen. 5.3 moles carbon dioxide are recovered from the reaction. What is the % yield?
CH4(g) + O2(g) à CO2(g) + H2O(g)
a) 38%
b) 44%
c) 76%
d) 88%
8. Consider the following reaction and choose the one incorrect statement from the choices below:
2 HBr (aq) + Ca(OH)2 (aq) à CaBr2 (aq) + 2 H2O
a) This is the reaction of a strong acid and a strong base.
b) Calcium and bromide are spectator ions in this reaction.
c) No precipitate forms in this reaction.
d) The water molecules formed in the reaction are completely ionized.
e) The conjugate acid of the hydroxide ion is water.
9. Consider the following unbalanced redox reaction, and choose the incorrect statement. Note: It is not necessary to balance this reaction in order to answer the question.
Ag(s) + NO3-(aq) à Ag+(aq) + NO(g)
a) In this reaction, silver is being oxidized.
b) In this reaction, silver is the reducing agent.
c) In this reaction, oxygen is the oxidizing agent.
d) In this reaction, the nitrogen atom is gaining three electrons
Form 2 had a slightly different set of answers:
a) In this reaction, silver is being oxidized.
b) In this reaction, oxygen is the reducing agent.
c) In this reaction, nitrogen is the oxidizing agent.
d) In this reaction, the nitrogen atom is gaining three electrons
10. Balance the following redox reaction in acid, then choose the incorrect statement about the balanced equation:
Ag(s) + NO3-(aq) à Ag+(aq) + NO(g)
Use this space for balancing:
a) In the balanced equation, 3 electrons are being transferred.
b) In the balanced equation, the net charge on each side of the equation is 3+.
c) In the balanced equation, hydrogen ions appear on the right.
d) In the balanced equation, two water molecules are formed.
11. 39.8 g of barium chloride is dissolved in water and the solution is brought to a final volume of 357 mL. What is the molarity of the chloride ion in this solution?
a) [Cl-] = 0.192 M
b) [Cl-] = 0.385 M
c) [Cl-] = 0.539 M
d) [Cl-] = 1.08 M
12. Consider a fixed amount of gas. Which of the following is incorrect?
a) When the volume is increased at constant temperature, the pressure increases.
b) When the temperature is decreased at constant pressure, the volume decreases.
c) When the pressure is increased at constant temperature, the volume decreases.
d) When the temperature is increased at constant volume, the pressure increases.
13. 1.04 g of nitrogen gas is placed in a container under a pressure of 0.641 atm, and a temperature of 315 K. What is the volume of the container?
a) 1.50 L
b) 0.037 L
c) 0.960 L
d) 7.77 L
14. My cat Gilbert can inhale a volume of 0.746 L of air in a single breath. If the air she breathes is 21.1% O2, how many O2 molecules is she inhaling per breath at STP (standard temperature/pressure)?
a) 9.50 x 1021 O2 molecules
b) 1.99 x 1022 O2 molecules
c) 4.23 x 1021 O2 molecules
d) 9.47 x 1022 O2 molecules
15. A 358 mL sample of hydrogen gas was collected at 22° C and 720 mm Hg. The vapor pressure of water at 22°C is 19.8 mm Hg. What is the volume of the dry H2 at STP?
a) 420 mL
b) 305 mL
c) 314 mL
d) 348 mL
16. A gas effuses 1.55 times faster than propane (C3H8) at the same temperature and pressure. Which gas is it?
a) H2O
b) NH3
c) CO2
d) C2H2
e) C4H10
17. Consider the depiction of the visible spectrum below, where wavelength is given in nanometers. Which one of the following statements is incorrect?
a) Orange light has a higher frequency than blue light.
b) Green light has a longer wavelength than indigo light.
c) Blue light is higher energy than green light.
d) Yellow light has a higher frequency than red light.
18. Which atoms in the third period have ground state electron configurations containing two half filled p orbitals?
a) Al, Si and P
b) Si, Ge, and Sn
c) P, S and Cl
d) Si and S
e) Al and Cl
19. Which of the following has the electron configuration 1s22s22p63s23p63d10 ?
a) Zn
b) Zn2+
c) Ni
d) Cl
e) Cl-
20. Which of the following has 24 valence electrons?
a) C3H8
b) HNO2
c) CH3CO2-
d) HSO4-
e) O3
21. Which of the following is the best Lewis structure for PCl3?
The answer is c
22. Assign formal charge ( if any) for each atom in the molecule shown below.
a) all atoms are neutral
b) N= +1, S = -2
c) N= -1, O= +1
d) C= +1, N= -1, O= -1
e) N= +1, O= -1
23. Which is the most polar bond?
a) C-N
b) C-O
c) O-H
d) C-H
24. Which of the following molecules has tetrahedral geometry?
a) C2H4
b) XeBr4
c) ClBr3
d) NH4+
25. Sulfur dioxide is expected to have what type of geometry?
a) linear
b) trigonal planar
c) tetrahedral
d) trigonal bipyramid
e) octahedral
26. Consider BF3, BH3, NO3-, O2, and O3. Which one is polar?
a) BF3
b) BH3
c) NO3-
d) O2
e) O3
27. Last week was the 20th anniversary of the Bhopal disaster, in which 40 tons of methyl isocyanate was released from a Union Carbide factory into the atmosphere of Bhopal, India. 18,000 people died of methyl isocyanate poisoning, and it is estimated that up to 600,000 more have suffered medical problems since then due to inhalation of this compound. Shown below is the Lewis structure of methyl isocyanate. What is the hybridization of each of the atoms in the molecule?
a) C1 = sp3, N=sp3, C2=sp2, O=sp2
b) C1 = sp, N=sp2, C2=sp3, O=sp3
c) C1 = sp3, N=sp2, C2=sp, O=sp2
d) C1 = sp2, N=sp3, C2=sp2, O=sp3
28. This question is worth 3 points: Which of the following atoms is the largest?
a) Rb
b) Ca
c) Br