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QUESTION 1 Which of the following statements is false ? The vapor pressure of a

ID: 850110 • Letter: Q

Question

QUESTION 1

Which of the following statements is false?

The vapor pressure of a substance increases as temperature increases.

The vapor pressure of a substance with weak intermolecular forces is greater than that of a substance with strong intermolecular forces (at the same temperature).

A substance boils when its vapor pressure is equal to the atmospheric pressure.

The boiling point of water increases as atmospheric pressure increases.

The viscosity of a liquid increases as temperature increases.

4 points   

QUESTION 2

Which of the following best describes a chemical reaction in a state of equilibrium?

Both the forward and the reverse reactions do not occur.

The rates of the forward and reverse reactions are equal.

The concentrations of the reactants equal the concentrations of the products.

All of one reactant has been consumed.

The value of the equilibrium constant is 1.

4 points   

QUESTION 3

Which of the following best describes any reaction system where Q > Kc?

The system will never be able to reach a state of equilibrium.

The system is at equilibrium, and there are more products than reactants at equilibrium.

The system is at equilibrium, and there are more reactants than products at equilibrium.

The system is not at equilibrium, and the reaction will go in the reverse direction.

The system is not at equilibrium, and the reaction will go in the forward direction.

4 points   

QUESTION 4

Which of the following substances has hydrogen bonding when in the pure liquid state?

CH3-O-CH3

CH3NH2

CH4

H2

All of these have hydrogen bonding in the pure liquid state.

4 points   

QUESTION 5

Which of the following should be the most soluble in water?

C6H14

I2

CCl4

O2

HOCH2CH2OH

4 points   

QUESTION 6

Concentration of H2 vs time data was collected for the following reaction. The initial rate of disappearance of H2 was determined to be 6.0103M/s. What is the initial rate of appearance of NH3 during the same time period?

N2(g) + 3H2(g)  ? 2NH3(g)  

4.0103M/s

1.0103M/s

2.0103M/s

5.4102M/s

9.0103M/s

4 points   

QUESTION 7

Which of the following will NOT change if the temperature of a reaction system is changed?

Frequency of molecular collisions

Average kinetic energy of reactant molecules

Reaction rate

Rate constant

Activation energy

4 points   

QUESTION 8

Identify the intermediate(s) in the following mechanism:

Step 1:   NO2(g) + NO2(g) ? NO3(g) + NO(g)
Step 2:   NO3(g) + CO(g) ? NO2(g) + CO2(g)  

NO

NO2

NO3

NO3 and NO

CO

4 points   

QUESTION 9

Which of the following reduces the solubility of a gas in solution?

Increasing gas pressure and increasing temperature

Increasing gas pressure and decreasing temperature

Decreasing gas pressure and increasing temperature

Decreasing gas pressure and decreasing temperature

Adding more water

4 points   

QUESTION 10

Which of the following occurs when the volume of a contained gas is reduced at constant temperature?

Pressure decreases

Average molecular velocity increases

Average kinetic energy increases

Atom size decreases

Collision frequency increases

4 points   

QUESTION 11

The half-life for a reaction that is first-order in A is 25 seconds. How long will it take for the concentration of A to change from 0.12 M to 0.030 M?

A(g) ?   B(g) + C(g)

25 s

38 s

50 s

75 s

100 s

4 points   

QUESTION 12

Given a fixed amount of an ideal gas held at constant pressure, calculate the volume it would occupy if a 2.00 L sample were cooled from 60.0C to 30.0C.

1.00 L

4.00 L

0.20 L

1.82 L

0.455 L

4 points   

QUESTION 13

What is the equilibrium constant expression for Kc for the following heterogeneous equilibrium?

2POCl3(s) <----> 2PCl3(g) + O2(g)

4 points   

QUESTION 14

What is the density (g/L) of O2 gas at a temperature of 283 K and 0.500 atm? (Hint: One approach is to assume a sample size of 1.0 L.)

0.345 g/L

524 g/L

1.48103 g/L

1.43 g/L

0.689 g/L

4 points   

QUESTION 15

Consider the following endothermic reaction at equilibrium in a 1-liter container:

2Cl2(g) + 2H2O(g) <----> 4HCl(g) + O2(g)           ?H > 0

Which of the following will cause a decrease in the equilibrium concentration of O2?

Increasing the temperature

Adding Cl2 gas

Adding HCl gas

Adding O2

Increasing the volume of the container

4 points   

QUESTION 16

Given that the molar volume of Ne gas is 22.414 L/mol at STP (1.00 atm of pressure and at a temperature of 273.15 K), predict the volume of He gas when the number of moles is 0.100 mol under the same conditions of temperature and pressure.

2.24 L

0.224 L

11.2 L

0.444 L

4.44 L

4 points   

QUESTION 17

In the following 2-step mechanism, which is the catalyst?

Step 1:   A + B  ? C + D
Step 2:   D + A   ? B + X

A

B

C

D

X

4 points   

QUESTION 18

Use the initial concentration and initial rate data in the table to determine the rate law for the reaction:  
A(aq) + B(aq)   ?   C(aq) + D(g)

Rate = k[A]

Rate = k[B]2

Rate = k[B]

Rate = k[A]2[B]

Rate = k[A][B]2

4 points   

QUESTION 19

Which of the following does NOT describe semiconductors?

Their band gaps are between metals and insulators.

Doped p-type and n-type semiconductors are more conductive than semiconductor materials that are not doped.

Their band gaps increase as particle size decreases in the 1-10 nm range.

They are superconducting when doped with a small amount of phosphorus.

They usually have an average number of 4 valence electrons per atom.

4 points   

QUESTION 20

Which of the following best explains the relative boiling points for H2S and SO2?

H2S has the higher boiling point because liquid H2S has hydrogen-bonding interactions while liquid SO2 has no hydrogen bonding interactions.

H2S has the higher boiling point because liquid H2S has dipole-dipole forces while liquid SO2 does not have dipole-dipole forces.

SO2 has the higher boiling point because liquid SO2 has stronger London-dispersion forces than liquid H2S.

SO2 has the higher boiling point because liquid SO2 has stronger dipole-dipole forces than liquid H2S.

4 points   

QUESTION 21

Which of the following gases has the greatest average molecular velocity when at the same temperature?

Ne

Xe

N2

F2

All of these have the same average molecular velocity.

4 points   

QUESTION 22

When comparing a 1 m NaCl solution to that of pure water:

The 1 m NaCl solution has a higher boiling point and the higher freezing point.

The 1 m NaCl solution has a higher boiling point and a lower freezing point.

The 1 m NaCl solution has a lower boiling point and a higher freezing point.

The 1 m NaCl solution has a lower boiling point and a lower freezing point.

They both have the same boiling point and freezing point.

4 points   

QUESTION 23

A 1-liter reaction container is filled with 1.20 mol H2 and 1.20 mol I2 where they reacted to form HI. The concentration of H2 was measured during the reaction at specific time intervals:

Time (s)

0.0

30

60

Concentration of H2 (M)

1.20

0.89

0.71

0.030 M/s

0.0060M/s

34 M/s

97 M/s

0.010 M/s

4 points   

QUESTION 24

Which of the following types of solids have relatively low melting points, because melting these solids requires breaking intermolecular forces, not real bonds?

Molecular solids

Ionic solids

Covalent-network solids

Metallic solids

Semiconductors

4 points   

QUESTION 25

Consider the following exothermic reaction at a state of equilibrium: C(s) + O2(g) <----> CO2(g) . Which of the following changes will cause value of the equilibrium constant Kc to change?

Increasing the container volume

Increasing the temperature

Removing O2

Adding solid carbon

All of these

4 points   

The vapor pressure of a substance increases as temperature increases.

The vapor pressure of a substance with weak intermolecular forces is greater than that of a substance with strong intermolecular forces (at the same temperature).

A substance boils when its vapor pressure is equal to the atmospheric pressure.

The boiling point of water increases as atmospheric pressure increases.

The viscosity of a liquid increases as temperature increases.

QUESTION 1 Which of the following statements is false? The vapor pressure of a substance increases as temperature increases. The vapor pressure of a substance with weak intermolecular forces is greater than that of a substance with strong intermolecular forces (at the same temperature). A substance boils when its vapor pressure is equal to the atmospheric pressure. The boiling point of water increases as atmospheric pressure increases. The viscosity of a liquid increases as temperature increases. 4 points QUESTION 2 Which of the following best describes a chemical reaction in a state of equilibrium? Both the forward and the reverse reactions do not occur. The rates of the forward and reverse reactions are equal. The concentrations of the reactants equal the concentrations of the products. All of one reactant has been consumed. The value of the equilibrium constant is 1. 4 points QUESTION 3 Which of the following best describes any reaction system where Q > Kc? The system will never be able to reach a state of equilibrium. The system is at equilibrium, and there are more products than reactants at equilibrium. The system is at equilibrium, and there are more reactants than products at equilibrium. The system is not at equilibrium, and the reaction will go in the reverse direction. The system is not at equilibrium, and the reaction will go in the forward direction. 4 points QUESTION 4 Which of the following substances has hydrogen bonding when in the pure liquid state? 4 points QUESTION 5 Which of the following should be the most soluble in water? 4 points QUESTION 6 Concentration of H2 vs time data was collected for the following reaction. The initial rate of disappearance of H2 was determined to be 6.0103M/s. What is the initial rate of appearance of NH3 during the same time period? 4 points QUESTION 7 Which of the following will NOT change if the temperature of a reaction system is changed? 4 points QUESTION 8 Identify the intermediate(s) in the following mechanism: 4 points QUESTION 9 Which of the following reduces the solubility of a gas in solution? QUESTION 10 Which of the following occurs when the volume of a contained gas is reduced at constant temperature? QUESTION 11 The half-life for a reaction that is first-order in A is 25 seconds. How long will it take for the concentration of A to change from 0.12 M to 0.030 M? QUESTION 12 Given a fixed amount of an ideal gas held at constant pressure, calculate the volume it would occupy if a 2.00 L sample were cooled from 60.0C to 30.0C.

Explanation / Answer

QUESTION 1

Which of the following statements is false?

The vapor pressure of a substance increases as temperature increases.

The vapor pressure of a substance with weak intermolecular forces is greater than that of a substance with strong intermolecular forces (at the same temperature).

A substance boils when its vapor pressure is equal to the atmospheric pressure.

The boiling point of water increases as atmospheric pressure increases.

The viscosity of a liquid increases as temperature increases.

4 points   

QUESTION 2

Which of the following best describes a chemical reaction in a state of equilibrium?

Both the forward and the reverse reactions do not occur.

R : At eqbm., net rate of the reaction is zero.

The rates of the forward and reverse reactions are equal.

The concentrations of the reactants equal the concentrations of the products.

All of one reactant has been consumed.

The value of the equilibrium constant is 1.

4 points   

QUESTION 3

Which of the following best describes any reaction system where Q > Kc?

The system will never be able to reach a state of equilibrium.

The system is at equilibrium, and there are more products than reactants at equilibrium.

The system is at equilibrium, and there are more reactants than products at equilibrium.

The system is not at equilibrium, and the reaction will go in the reverse direction.

The system is not at equilibrium, and the reaction will go in the forward direction.

4 points   

QUESTION 4

Which of the following substances has hydrogen bonding when in the pure liquid state?

CH3-O-CH3

CH3NH2

CH4

H2

All of these have hydrogen bonding in the pure liquid state.

4 points   

QUESTION 5

Which of the following should be the most soluble in water?

C6H14

I2

CCl4

O2

HOCH2CH2OH

4 points   

QUESTION 6

Concentration of H2 vs time data was collected for the following reaction. The initial rate of disappearance of H2 was determined to be 6.0

The vapor pressure of a substance increases as temperature increases.

The vapor pressure of a substance with weak intermolecular forces is greater than that of a substance with strong intermolecular forces (at the same temperature).

A substance boils when its vapor pressure is equal to the atmospheric pressure.

The boiling point of water increases as atmospheric pressure increases.

The viscosity of a liquid increases as temperature increases.

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