CHEM 1212 Chemistry Questions

CHEM 1212: Chapter 6 Class Participation, Spring 2022Question 1: Choose the response that lists the member of each of the following pairs that has
the lower boiling point.
i.
H2O or LiBr
ii.
HF or HCl
iii.
CH3CH3 and HO-CH2CH2-OH
A.
B.
C.
D.
E.
H2O,HF, CH3CH3
H2O,HCl, CH3CH3
H2O,HF, HO-CH2CH2-OH
LiBr, HCl, HO-CH2CH2-OH
LiBr,HF, HO-CH2CH2-OH
Question 2: Which one of the following would you expect to be most soluble in water? (Red=
oxygen, green=chlorine, black = carbon, white = hydrogen)
A.
B.
D.
E.
C.
Question 3: Of the solvent/solute pairs given, which of the solutes would you expect to be least
soluble in the solvent? Red= oxygen, green=chlorine, black = carbon, white = hydrogen)
A.
in
B.
in
C.
in
i
n
Question 4: Consider the expression below, showing the terms which contribute to the heat of
solution, ‘Hsoln:
‘Hsoln = ‘Hsolute + ‘Hsolvent + ‘Hmix.
Which of the following sets correctly shows the signs (positive or negative) of the three terms
on the right-hand side of the equation?
A. ‘Hsolute > 0; ‘Hsolvent > 0; ‘Hmix > 0
B. ‘Hsolute < 0; 'Hsolvent < 0; 'Hmix 0; 'Hmix < 0 D. 'Hsolute < 0; 'Hsolvent < 0; 'Hmix > 0
E. ‘Hsolute < 0; 'Hsolvent > 0; ‘Hmix < 0 Question 5: In general, a process that is exothermic is favorably spontaneous. When ammonium nitrate, NH4NO3, is dissolved in water, the process is endothermic yet still spontaneous. Why is this process spontaneous? (Recall that there are three steps in the dissolution process). A. The process of separating the ammonium ions from the nitrate ions in the crystal lattice of NH4NO3 (Step 1) is exothermic thus favoring a spontaneous process. B. The process of separating water molecules from water molecules (Step 2) is exothermic thus favoring a spontaneous process. C. Steps 1 and 2 are both exothermic and thus the process is spontaneous. D. The process is spontaneous because the overall solution upon mixing is more disordered than the pure substances NH4NO3 and water (the entropy factor), even though the overall mixing process is endothermic. Question 6: Which of these statements is generally TRUE? A. The solubility of a solid is not dependent on either temperature or pressure. B. The solubility of a solid is highly dependent on pressure. C. The solubility of a solid is highly dependent on both pressure and temperature. D. The solubility of a solid is highly dependent on temperature. E. None of the above. Question 7: Question 8: To the right is the phase diagram for iodine. Which of the following transitions occur when the temperature and pressure conditions are changed from A to B to C to D? A. l → s → g → l B. s → l → g → s C. g → s → l → g A D. s → l → g → l → s D B C Chapter 9 Practice Question 1: A ballerina weighs 103 lbs and is up on her toes with only 10.0 cm2 of her slippers in contact with the floor. What pressure is she exerting on the floor? A. 4.59 × 105 Pa B. 4.59 × 103 Pa C. 4.59 × 101 Pa D. 4.59 × 10-1 Pa E. 4.59 × 10-3 Pa Question 2: Mercury has a density of 13.6 g/cm3, and water has a density of 1.00 g/cm3. If a column of mercury has a height of 755 mm, how high would a corresponding column of water be in feet? A. 33.7 feet B. 1026 feet C. 1006264 feet D. 100.7 feet Question 3: A student performed an endothermic reaction in an evacuated flask attached to an open-end manometer. Being in a hurry, the student did not allow the flask to warm to room temperature before the student took the reading. The incorrectly recorded pressure will be_______ . A. higher than the actual value. B. lower than the actual value. C. correct, as temperature would not affect the measured pressure. Question 4: Suppose you put a helium-filled balloon in the trunk of your car on a hot day. What would happen to the balloon? A. The balloon would expand. B. The balloon would shrink. C. The balloon would remain the same. D. None of the above. Question 5: Suppose you put a helium tank in the trunk of your car on a hot day. What would happen to the tank? A. The tank would shrink. B. The helium’s pressure inside the tank would decrease. C. The pressure inside the tank would increase. D. The tank would expand E. None of these. Question 6: As the temperature increases, what is happening to the helium atoms inside the balloon and tank? A. The helium atoms are slowing down. 1 B. The helium atoms are sticking to each other and colliding less with their container. C. The helium atoms are moving faster and colliding more with their container. D. The helium is reacting to form larger compounds Questions 7-9 are based on the following figure: Question 7: The pink balloons contain hydrogen, the yellow balloons contain nitrogen, and the gray balloons contain oxygen. Over time, which balloon would you expect to shrink the quickest? A. A B. D C. G Question 8: If the smaller yellow balloon in [D] corresponds to the particulate view in [E], which particulate view corresponds to the larger yellow balloon in [F] if no additional nitrogen has been added? The pink balloons contain hydrogen, the yellow balloons contain nitrogen, and the gray balloons contain oxygen. A. B B. E C. H D. None of the representations Question 9: 2 If the smaller pink balloon in [A] corresponds to the particulate view in [B], which of the following changes would cause the larger pink balloon in [C] to correspond to the particulate view in [B] as well? The pink balloons contain hydrogen, the yellow balloons contain nitrogen, and the gray balloons contain oxygen. A. Decrease in the moles of hydrogen B. Increase in temperature C. Decrease in pressure D. Increase in the moles of hydrogen Question 10: A 2.650 g sample of a gas occupies a volume of 428 mL at 0.9767 atm and 297.3 K. What is its molar mass? [ANSWER] A. 97.5 g/mol B. 123 g/mol C. 155 g/mol D. 186 g/mol Question 11: A fixed quantity of gas, initially at 600ºC, undergoes a temperature change at constant pressure in a cylinder with a movable piston. What final temperature of the gas can result in the change of state depicted below? A. 1473ºC B. 1200ºC C. 600ºC D. 300ºC E. 143ºC Question 12: You are holding four identical balloons each containing 10.0 g of a different gas. The balloon containing which gas is the largest balloon A. Ar B. CH4 C. CS2 D. H2S E. Not enough information to decide Question 13: Select all the correct statement(s): i. The pressure of an ideal gas is tripled. If the temperature and amount of gas are held constant, the volume decreases to 1/3 of its original value. ii. If 0.16 mol of hydrogen gas (H2) has a volume of 4.9 L, under the same conditions, the volume of 0.052 mol of oxygen gas (O2) is 1.8 L. iii. If a balloon contains 413 mL of gas at 22.10°C and 1 atm, its volume at 4.10°C and 1 atm pressure is 776 mL. a) i and ii 3 b) i,ii, and iii c) i only d) ii only e) i and iii . Question 14: Select the correct statement(s): i. The pressure of an ideal gas is doubled. If the temperature and amount of gas is held constant, the volume is decreased to 1/2 its original value. ii. The temperature of a sample of an ideal gas is doubled. If the pressure and amount of gas remain the same, the volume will double. iii. If a chemist removes 21% of the gas from a balloon, and the pressure and temperature of the gas do not change, the volume increases by 21%. a) ii only b) ii and iii c) i only d) i,ii, and iii e) i and ii . Question 15: Which gas has the highest density at STP: A) F2 B) H2 C) N2 D) Br2 E) Cl2 Question 16: Which of the following will increase the volume of 1 mol of an ideal gas? (Select all that apply). A. Temperature decreases from 800K to 400 K (at constant P) B. Temperature increases from 250K to 500 K (at constant P) C. Pressure increases from 2 atm to 6 atm (at constant T) D. Half the gas escapes at (constant P and T) E. Both the pressure and the temperature decrease to 1/4th of their initial values. 4 Question 17: A 3.0-L sample of helium was placed in a container fitted with a porous membrane. Half of the helium effused through the membrane in 24 hours. A 3.0-L sample of oxygen was placed in an identical container. How many hours will it take for half of the oxygen to effuse through the membrane A. B. C. D. E. 8.5 h 12 h 48 h 60. h 68 h Question 18: A compound composed of carbon, hydrogen, and chlorine effuses through a pinhole 0.411 times as fast as neon. Select the correct molecular formula for the compound. A. B. C. D. E. CHCl3 CH2Cl2 C2H2Cl2 C2H3Cl CCl4 Question 19: At what temperature in kelvin is the root mean square speed of helium atoms (atomic weight = 4.00) equal to that of oxygen molecules (molecular weight = 32.00) at 300. K? A. B. C. D. E. 37.5 K 75 K 106 K 292 K 2400. K Question 20: Three 5-L flasks, fixed with pressure gauges and small valves, each contain 4 g of gas at 273 K. Flask A contains H2, flask B contains He, and flask C contains CH4. Rank the flask contents in terms of: 1. Pressure 2. Kinetic Energy 3. Effusion rate after the valve is opened 4. Density 5