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Assorted State Change Questions

1 Describe the intermolecular force that must be overcome in converting each of the following from a liquid to a gas:

A. Liquid O2
B. Mercury
C. CH3I (methyl iodide)
D. CH3CH2OH (ethanol)

2 Rank the following in order of increasing strength of intermolecular forces in the pure substances. Which do you think might exist as gasses at 25"C and 1 atm: Ne, CH2, CO, and CCl4?

3 Explain why the boiling point of H2S is lower than that of water?

4 Which of the following compounds would be expected to form intermolecular hydrogen bonds in the liquid state?

A. CH3OCH3 (dimethyl either)
B. CH4
C. HF
D. CH3CO2H (acetic acid)
E. Br2
F. CH3OH (methanol)

5 The enthalpy of vaporization of liquid mercury is 59.11 kj/mol. What quantity of heat is required to vaporize 0.500 mL of mercury at 357'C, its normal boiling point? (The density of mercury is 13.6 g/mL.)

6 Assume you seal 0.1 g of diethyl ether in an evacuated 100.-mL flask. There are no molecules of any other gas in the flask. If the flask is held at 30'C, what is the approximate gas pressure in the flask? If the flask is place in an ice bath, does additional liquid ether evaporate of does some ether condense to a liquid?

7 Rank the following substances in order of increasing strength of intermolecular forces:
A. Ar
B. CH3Oh
C. Co2
D. Cao

8. If you place 1.0 of ethanol in a room that is 3.0 m long, 2.5 wide, and 2.5 high, does all the alcohol evaporate? If some liquid remains, how much remains? The vapor pressure of ethanol at 25'C is 59 mm Hg, and the density of the liquid at this temp is 0.785 g/cm3.

Solution Preview

liquid to a gas:

A. Liquid O2 This is a compound that is made of non-polar molecules, the main forces that hold these molecules together are the London dispersion (induced dipole-induced dipole) forces....very weak...very easily broken...very low BP
B. Mercury This is a unique compound in that it is the only liquid metal at room temperature. The intermolecular forces are the metal bonding forces.
C. CH3I (methyl iodide) This compound has a little polarity to its molecule, so the forces are dipole-dipole interactions
D. CH3CH2OH (ethanol) This compound features an -OH functional group, therefore it has not only dipole-dipole interactions but also hydrogen bonding (higher in strength than simple dipole-dipole.

2 Rank the following in order of increasing strength of intermolecular forces in the pure substances. Which do you think might exist as gasses at 25"C and 1 atm: Ne, CH2, CO, and ...

Solution Summary

Solution answers 8 questions touching upon everything from enthalpy of vaporization to boiling points, with answers fully explained and a well-formatted version attached in Word.

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