Multiple Choice Answers

The following reaction is second order in [A] and second order overall.
2A –> B + C
The instantaneous rate of reaction is 1.8 × 10-3 M/s when [A] is equal to 0.63 M. What is the rate constant, k, of this reaction?
1.4 × 10-3 M-1s-1
2.2 × 102 M-1s-1
4.5 × 10-3 M-1s-1
7.1 × 10-4 M-1s-1

Two gas tanks are linked by a connecting tube of negligible volume with a valve. One contains 15 L of nitrogen at 7.2 atm of pressure. The other contains 8.3 L of helium at 4.1 atm of pressure. If the valve is opened, what is the final pressure of the two tanks combined?
142 atm
4.5 atm
6.1 atm
0.48 atm

Which of the following steps illustrates work being done?
A beaker of water being heated from 25°C to 75°C.
A battery producing 1.5 V.
A box being pushed up a ramp.
A log burning in a fireplace.

Which of the following has the highest number of Calories?
7.2 g of fat
9.8 g of starch
15.5 g of sugar
14.3 g protein

What is the sign of q when heat moves from the surroundings to the system?
It depends on the value of work.
Positive
Negative
This situation never occurs.

Which of the following is true about an endothermic reaction?
The reactants have a lower enthalpy than the products.
The reactants have a higher enthalpy than the products.
The reactants have the same enthalpy as the products.

For the reaction:
6HCl(aq) + 2Fe(s) –> 2FeCl3(aq) + 3H2(g)

Which of the following rate expressions is NOT correct?
Rate = -[HCl]/6t
Rate = -[Fe]/2t
Rate = 2[FeCl3]/t
Rate = [H2]/3t

The rate equation for the synthesis of water
2H2 + O2 –> 2H2O
Is Rate = k[H2][O2]
What is the overall order of this reaction?
0
1
2
3

The activation energy (Ea) on a reaction diagram for an uncatalyzed reaction is generally ________ a catalyzed reaction.
the same as
unrelated to
greater than
less than

In a reaction, the equilibrium constant for the forward reaction is Kf and the equilibrium constant of the backward reaction is Kb. What is the relationship between Kf and Kb?
Kf = Kb
Kb = 1 + Kf
Kf = 1/Kb

A simple dissociation reaction is written for each of the following acids. Which one is least correct?
Hydrochloric acid:
The ammonium ion:
Acetic acid:
The hydrated aluminum (III) ion:

What is the [H3O+] in a solution with a pH of 2.34?
4.57 x 10-3 M
4.6 x 10-3 M
4.57 x 103 M
4.6 x 103 M

A 0.200 M solution of a weak acid, HA, is 9.4% ionized. Using this information, calculate Ka for HA.
1.8 x 10-3
3.8 x 10-3
9.4 x 10-3
1.9 x 10-2

Which of the following is not a buffer solution?
a weak acid (to neutralize a strong base) and its conjugate base (to neutralize a strong acid)
a weak base (to neutralize a strong acid) and its conjugate acid (to neutralize a strong base)
a strong acid (to neutralize a strong base) and its conjugate base (to neutralize a strong acid)
formic acid and sodium formate

Which statement about alcohols is not correct?
Alcohols contain hydroxyl functional groups.
Alcohols are organic molecules.
Alcohols contain nitrogen.
Alcohols are named by their Greek prefix
+ -anol.

Which of the following shows the alkanes in correct order from lowest to highest boiling points?
hexane, pentane, butane, propane, ethane, methane
hexane, ethane, propane, butane, pentane, methane
methane, ethane, propane, butane, pentane, hexane
methane, ethane, propane, pentane, butane, hexane

Which characteristic defines the main difference between a basic buffer system and an acidic buffer system?
A basic buffer system uses more base than acid per liter.
A basic buffer system is a solution that can maintain an acidic pH when more acid or base is added.
A basic buffer system maintains a steady basic pH regardless of how much acid or base is added.
A basic buffer system is a solution that can maintain a basic pH when more acid or base is added.
In a manometer the mercury level at the open ed of the tube is 215 mm higher than at the closed end of the tube. If the atmospheric pressure is 1 atm, what is the pressure of the gas sample in units of torr?
1.28 torr
545 torr
975 torr
215 torr

Using Boyle’s Law, predict what will happen to the pressure of a gas in a container at constant temperature, if the volume of the container is changed to one-half its original size.
Nothing will happen to the pressure.
The pressure will be decrease to one-half its original value.
The pressure will increase to twice its original value.
More information is needed.

A sample of gas is heated. During the heating process, the volume of the gas increases 1.7 times. If the initial temperature of the gas is 80°C, what is the final temperature of the gas?
136°C
600 K
210 K
353 K

Suppose that you have a 2.0 L sample of hydrogen at 1.00 atm and 59°C. If you heat the sample to 84°C and it expands to a volume of 3.7 L, what will the final pressure be?
0.58 atm
0.76 atm
0.54 atm
1.00 atm

A helium balloon with a volume of 2.4 L contains 0.10 moles of gas at 25°C and 1 atm of pressure. The balloon leaks 0.02 moles of gas until someone manages to seal the hole. What is the new volume of the balloon?
3.0 L
0.5 L
19.2 L
2 L

There is an unlabeled gas cylinder in the chemistry lab. The cylinder contains a gaseous compound. A sample of the compound shows that it contains 27.27% carbon and 72.73% oxygen. The 1.50 L bottle was found at STP and contained 2.94 g of the compound. Identify the number of moles of the compound in the bottle.
1.96 mol
0.0669 mol
0.105 mol
0.0609 mol