CHEM 104: General Chemistry II
Spring 2014 Exam 1
1. Do NOT open this exam until you are told to do so. Opening the exam before the start of the exam is considered an act of Academic Dishonesty. 2. All answers must be bubbled into the scantron answer sheet. 3. No credit will be given for answers written on this exam. 4. You must use a #2 pencil to bubble in the answers on your scantron. 5. This is a multiple choice exam consisting of 30 questions (7 pages). Each question is worth 3.33 points. 6. There is one extra credit question on this exam (page 8). The extra credit question is worth an additional 5 points. 7. Attached to the back of this exam you will find 3 blank pages, an appendix (formula sheet) and a periodic table. You may remove these from the exam at your convenience. 8. On the FRONT of your scantron.
Write your last name, followed by your first name.
Write your exam version (A or B)
9. On the BACK of your scantron:
Write and bubble in BOTH your last and first name. Make sure to bubble in your names as follows: Last Name (leave a space) First Name NOTE: You must bubble in the space on your scantron!
Hunter College Academic Dishonesty Statement
Hunter College regards acts of academic dishonesty (e.g., plagiarism, cheating on examinations, obtaining unfair advantage, and falsification of records and official documents) as serious offenses against the values of intellectual honesty. The college is committed to enforcing the CUNY Policy on Academic Integrity and will pursue cases of academic dishonesty according to the Hunter College Academic Integrity Procedures. Any suspected cases of academic dishonesty will be reported without exception.
Multiple Choice Questions: (3.33 pts each)
For Questions 1 and 2 consider the phase diagram for substance X. Substance X is sensitive to changes in temperature and pressure and so it is stored in a sealed container at 24 atm and -100 °C.
1) According to the phase diagram to the right, substance X is stored as a_______________. a. solid
2) What will happen to substance X if the container is opened to the air and then allowed to slowly warm to 24 °C? a. Substance X freezes.
b. Substance X evaporates.
c. Substance X melts.
d. Substance X sublimes.
3) What is the sodium ion concentration in a solution prepared by mixing 70.0 mL of 3.0 M sodium carbonate (Na2CO3) with 30.0 mL of 1.0 M sodium bicarbonate (NaHCO3)? a. 0.45 M
b. 4.0 M
c. 4.5 M
d. 7.0 M
4) Which of the following solutes will produce the largest total molality of solute particles when dissolved in 1 kg of water? a. 1 mole of ethanol
b. 2 moles of NaCl
c. 2 moles of Mg(Cl)2
d. 3 moles of methanol
5) Use the table below to determine the molar composition of an ideal solution that is composed of methanol and propanol, and has a total vapor pressure of 109 torr at 30°C.
Vapor pressure at 30°C
a. 0.5 moles methanol, 0.5 moles propanol
b. 0.25 moles methanol, 0.75 moles propanol
c. 0.75 moles methanol, 0.25 moles propanol (partial credit for a reversed response) d. 0.4 moles of methanol, 0.6 moles propanol
6) When a nonvolatile solute is added to a volatile solvent, the solution vapor pressure ___________________, the boiling point__________________ and the freezing point___________________. a. decreases, increases, decreases
b. increases, increases, decreases (partial credit for knowing Bp and Fp but not Pvap) c. increases, decreases, increases
d. decreases, decreases, increases
7) A 5.50 g sample of a compound is dissolved in 250 grams of benzene solvent. The freezing point of this solution is 1.02° C below that of pure benzene. What is the molar mass of this compound? (Kf for benzene = 5.12° C/molal) a. 22.0 g/mol
b. 44.0 g/mol
c. 110 g/mol
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