Exam 3 Review Chem 110 MJ Bojan

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CHEM 110 EXAM 3 Mon. Apr. 1 6:30-7:45pm

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CHEM 110 EXAM 3 Mon. Apr. 1 6:30-7:45pm

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Regular Conflict 4:40-5:55 pm 101 Thomas

!   Covers: Lectures 22-33 !   Chapters 11, 10.4, 12, 9.1&5, 13

Format: 28 Multiple Choice questions

See sample practice exams on the Chem 110 Web page: select Handouts.

Properties of molecules !   gases

!   Kinetic Molecular Theory describes ideal gas

!   What is pressure?

!   What is temperature?

!   PV = nRT (gas density)

!   Dalton’s Law of partial pressures

!   Speeds of gases, Graham’s law of effusion (diffusion)

The height of the column of mercury in the manometer shown below is 73 mm Hg. If the external pressure is 743 torr , what is the gas

pressure inside the bulb?

Two separate glass bulbs, bulb A and bulb B, are both filled with helium. The pressure in bulb A is twice that of bulb B. The volume of bulb B is twice that of bulb A. If the gas in the bulbs remains at constant temperature, which of the following statements is true?

A. Bulb A has more helium atoms than bulb B.

B. Bulb B has more helium atoms than bulb A.

C. Bulb B and bulb A contain the same number of helium atoms.

D. The density of the helium in both bulbs is the same.

E. More information is needed to make any of these conclusions.

! !A B

Given the gas mixture described below, what is the partial pressure of Cl2?

Xi Pi Ptotal = 735 torr H2 0.090 ???

Vtotal = 8.00 L CO ??? 254 torr

T = 296 K Xe 0.007 5.15 torr N2 0.090 ??? Cl2 ??? ???

A. 343 torr

B. 387 torr

C. 476 torr

D. 735 torr

E. There is insufficient information to determine this answer.

Which of the gases (in the table below) has the greatest average kinetic energy?

A. H2

B. CO

C. Xe

D. Cl2

E. They all have the same average kinetic energy.

Xi Pi Ptotal = 735 torr H2 0.090 ???

Vtotal = 8.00 L CO ??? 254 torr

T = 296 K Xe 0.007 5.15 torr N2 0.090 ??? Cl2 ??? ???

Compare the root mean square speed of an O2 molecule with that of a CH4 molecule at the same temperature and pressure. Which of the following statements is true?

A. O2 is 2.5 times faster than CH4.

B. The speeds are the same because the molar masses of O2 and of CH4 are the same.

C. The speeds are the same because the temperature is constant.

D. CH4 is 2.00 times faster than O2.

E. CH4 is 1.41 times faster than O2.

Nitrogen gas is collected over water at 25.0°C and 740 torr. How many grams of nitrogen gas were collected if the volume was 10.5 L? The vapor pressure of water at 25.0°C is 23.8 torr

A 0.380 g

B. 5.66 g

C. 11.3 g

D. 11.7 g

E. 12.1 g

The plot shown below corresponds to one mole of each gas at 298 K. At low pressure (P = 20 atm) which gas deviates

the most from ideal gas law?

A. N2 B. CH4 C. H2 D. CO2 E. The temperature is too high: at

298 K all gases behave ideally.

In the equation shown below, what does the van der Waals constant, a, correct for?

(P + n2a/V2)(V – nb) = nRT

A. finite molecular volume

B. curvature in the trajectories of the gas molecules

C. intermolecular attractive forces between gas molecules

D. the average speed of the gas molecules

E. the density of gas molecules

Properties of liquids !   Extension of Kinetic Molecular Theory to liquids

!   role of intermolecular forces !   Cohesive forces vs. adhesive forces

!   Properties of liquids !   Surface tension !   Viscosity !   Capillary rise

!   Phase changes and heat curves !   Heat capacity of gas/liquids/solid !   Enthalpy change associated with phase changes

!   Vapor pressure

!   Phase diagram

Consider the heat curve shown. Which one of the arrows on the phase diagram describes the heat changes indicated by starting at the point labeled I and ending at F?

!"

#$%&"

•  I

•  F

A B C

D E

Which of the following statements are true?

1. During a phase transition from gas to solid, the average kinetic energy of the substance decreases.

2. During a phase transition, the temperature of the substance increases.

3.  When a phase transition occurs, the average kinetic energy remains the same.

A hot solid substance at 150 °C and 1 atm with a heat capacity of 1.05 kJ/K is dropped into a 1 L beaker with 750

g of water at 10 °C. What is the final temperature of the water in the beaker?

The boiling point of water at 1 atm is 100 °C.

The enthalpy of vaporization of water is 40.1 kJ/mol.

Cs water = 4.184 J/g-K, Cs steam = 1.84 J/g-K.

The experimental heating curve shown was obtained while heating a

piece of C4H7COOH which was initially solid. Which of the

following statements are true?

1. The temperature at 1 is the melting point of C4H7COOH.

2. Both liquid and gas phases are present at 2.

3. The sample is in the gas phase at the end of the experiment.

4.  The heat capacity of the liquid is greater than the heat capacity of the solid.

!

Rank the following in order of increasing vapor pressure at 25°C.

Cl2 I2 Br2 CH4

A. I2 < Br2 < CH4 < Cl2

B. Cl2 < I2 < Br2 < CH4

C. Cl2 < CH4 < I2 < Br2

D. CH4 < Cl2 < Br2 < I2

E. I2 < Br2 < Cl2 < CH4

Given the following information, calculate the energy required to heat 1.70 mol H2O from the initial to final

temperature as indicated by the arrow.

C(ice) = 37.6 J/mol-°C ΔHfusion = 6.02 kJ/mol

C(water) = 75.3 J/mol-°C ΔHvap = 40.67 kJ/mol

C(vapor) = 33.1 J/mol-°C

A. 271 kJ

B. 1510 kJ

C. 15.0 kJ

D. 84.1 kJ

E. 15000 J

10.0

100

0.100

1000

1.00

0 100

H2O Phase Diagram

27 200Temperature ( oC)

Pre

ssur

e (a

tm)

10.0

100

0.100

1000

1.00

0 100

H2O Phase Diagram

27 200Temperature ( oC)

Pre

ssur

e (a

tm)

Properties of solutions

!   electrolytes

!   concentration

!   Dilution

Which of the following is not a strong electrolyte in aqueous solution?

A. Sr(NO3)2

B. H2SO4

C. Ba(OH)2

D. NH3

E. NaCl

The average concentration of cholesterol (C27H46O, MW = 386 g/mol) in human serum is 0.195 g per 100 mL. What is the average molar concentration of cholesterol in human serum?

A. 5.12 ! 10–2 M

B. 5.05 ! 10–3 M

C. 4.51 ! 10–3 M

D. 5.50 ! 10–4 M

E. 3.89 ! 101 M

When 25.0 mL of 0.400 M HClO4 and 50.0 mL of 0.850 M HNO3 are mixed, what is the molarity of H+ in the final solution?

A. 0.0625 M

B. 0.657 M

C. 0.700 M

D. 0.833 M

E. 0.882 M

Properties of solutions

!   Factors that affect solubility !   temperature

!   Pressure

!   Intermolecular forces

Which of the following aqueous solutions will have the greatest mass of solute at 30°C if they are saturated?

A. KClO3(aq)

B. KCl(aq)

C. KNO3(aq)

D. KCl and KNO3 will have the same K+(aq) concentration

E. They will all have the same concentration of K+(aq)

!

On a clear day, Harvey finds that the partial pressure of N2 in air is 0.78 atm, and the concentration of nitrogen in water is 5.3 ! 10–4 M. What is the partial pressure of N2 necessary to have a

concentration of 1.1 ! 10–3 M N2 in water?

A. 0.63 atm

B. 0.78 atm

C. 1.0 atm

D. 2.1 atm

E. 1.6 atm

The structures of 5 vitamins are shown. Based on these structures, which one of the following vitamins is water soluble?

Vitamin AOH

Vitamin B

N

N

NH2

N S

OHVitamin K

O

O

Vitamin D

HO

H

Vitamin E

O

HO

A.

E.

D.

C.

B.

Properties of solutions

!   Colligative properties !   Vapor pressure lowering

!   Boiling point elevation

!   Freezing point depression

!   Osmotic pressure

!   Colloids

Which one of the following aqueous solutions would have the highest vapor pressure at 25°C?

A. 0.3 m sucrose (table sugar)

B. 0.3 m AlCl3

C. 0.3 m NaCl

D. 0.3 m Ca3(PO4)2

E. 0.3 m MgCl2

12.3 g of an unknown nonelectrolyte is added to 200 g of benzene causing the freezing point of the solution to decrease from 5.45°C to 3.40°C. From the following data for benzene, calculate the molar mass of the unknown.

Kb = 2.53°C/m Kf = 5.12°C/m

A. 63.3 g/mol

B. 75.9 g/mol

C. 106 g/mol

D. 154 g/mol

E. 237 g/mol

George is making spaghetti for dinner. He places 4.01 kg of water in a pan and brings it to a boil. Before adding the pasta, he adds 58.0 g of table salt (NaCl) to the water and again brings it to a boil. What is the temperature of the salty, boiling water?

It is a nice day at sea level, with a barometric pressure of 1.00 atm. Assume negligible evaporation of water. Kb for water is 0.52°C/m.

A. 99.74°C

B. 99.87°C

C. 100.00°C

D. 100.13°C

E. 100.26°C

1.00 g of an unknown compound is dissolved in 50.0 mL of water. The osmotic pressure is found to be 2.41 atm at 300K. Identify the unknown.

A. C2H6O2

B. C11H12N2O2

C. C6H12O6

D. C9H17NO5

E. C12H22O11