Midterm Study Flashcards
Complete combustion of a sample of a hydrocarbon in excess oxygen produces equimolar quantities of carbon dioxide and water. Which of the following could be the molecular formula of the compound?
c. C4H8
Zn(s) is used to reduce other compounds in chemical reactions. If a chemist needs a substance that is more effective in its reducing ability, which of the following species would be the best choice?
a. Na
A kinetics experiment is set up to collect the gas that is generated when sample of chalk, consisting primarily of solid CaCO3, is added to a solution of ethnic acid(acetic acid) CH3COOH. The rate of reaction between CaCO3 and CH3COOH is determined by measuring the volume of gas generated at 25ºC and 1 atm as a function of time. Which of the following experimental conditions is most likely to increase the rate of gas production?
d. Decreasing the particle size of the CaCO3 by grinding it into a fine powder
H2(s)+I2(g)2HI(g). At 450ºC, 2.0 moles of H2, I2, and HI are combined in a 1.0 L rigid container. The value of Kc at 450ºC is 50. Which of the following will occur as the system moves toward equilibrium?
b. More HI will form
The graph above shows the speed distribution of molecules in a sample of gas at a certain temperature. Which the following graphs shows the speed distribution of the same molecules at a lower temperature (as a dashed curve)?
c.
The elements I and Te have similar atomic masses. A sample that was believed to be a mixture of I and Te was run through a mass spectrometer, resulting in the data above. If all of the following statements are true, which one would be the best basis for concluding that the sample was pure Te?
c. I only consists of one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope
All the reactions represented above occur in an aqueous solution of oxalic acid. Which of the following represent a Brønsted Lowry conjugate acid-base pair?
b. HC2O4 AND C2O4
Which of the following particulate diagrams shows the formation of water vapor from hydrogen gas and oxygen gas in a rigid container at 125ºC?
c.
At point R in the titration, which of the following species has the highest concentration?
a. HA
Which of the following is the best particulate representation of the species (other than H2O) that are present in significant concentrations in the solution at point U in the titration?
b. 
At which point on the titration curve is A- closest to twice that of HA?
c. T
A student carries out the same titration, but uses an indicator instead of a pH meter. If the indicator changed color slightly past the equivalence point, what will the student obtain for the calculated concentrations of the acid?
b. slightly more than 0.0800 M
The average kinetic energy of the gas molecules is:
d. The same in all three containers
The density of the gas, in g/L, is
b. greater in container B
The mass percent of carbon in pure glucose, C6H12O6, is 40.0%. A chemist analyzes an impure sample of glucose and determines that the mass percent of carbon is 38.2%. Which of the following impurities could account for the low mass of carbon in the sample?
a. Water (H2O)
Caffeine (C8H10N4O2) is a weak base with a Kb value of 4x10^-4. The pH of a .01 M solution of caffeine is in the range of:
d. 11-12
Which of the following statements is true?
d. The rate law that is consistent with this mechanism is:m rate=k[NO]^2[O2]
For which of acid is the value of the acid dissociation constant, Ka, the smallest?
a. Acid 1
Using the table and information from question #18, which of the four acids listed in the table is hydrochloric acid?
b. Acid 2
Using the information on the table in question #18 again, of the following species, which has the greatest concentration in a 1.0M solution of acid 1 at equilibrium?
c. Acid 1
If equal volumes of the four acids at a concentration of 0.50 M are each titrated with a strong base, which will require the greatest volume of base to reach the equivalence point?
d. All the acids will require the same volume of base to reach the equivalence point
A 25 mL sample of a 1.0 M solution of acid is mixed with 25 mL of .50 M NaOH. Which of the following best explains what happens to the pH of the picture when a few drops of 1.0 M HNO3 are added?
c. The pH of the picture stays about the same, because the conjugate base of acid 1 reacts with the added hydronium ions
Which of the following correctly describes the reaction?
b. the decomposition of N2O5 is a first order reaction
A proposed mechanism for destruction of ozone gas in the stratosphere is represented above. Which of the following is evidence that the mechanism is occurring?
a. The presence of Cl increases the rate of the overall reaction
