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					Tell which type of interaction ( dipole-dipole forces or London forces)exists between molecules in
the following table.

N2
CO2
CH3Cl
SO2

What is the reason that liquids have different normal boiling points


           Which molecule in the following pairs has stronger intermolecular forces?

           Identify the types of forces present for each molecule, London forces, LF; dipole-dipole
           forces,DD; hydrogen bonding, HB.



           molecule pair                 types of intermolecular force

           H2 or N2

           CH3Cl or CH4

           SO2 or CO2

           H2O or H2S

           Which of the following displays hydrogen bonding.

                    a. CH4
                           b. CH3OH
                           c. CH3OCH3
                           d. CH3CH2CH2CH3



                    Which of the following substances has the lowest
          melting point?
                                                              a. gold, Au
                                                              b. sand, SiO2
                                                              c. butane,
                                                              CH3CH2CH2CH3
                                                              , C4H10
                                                              d.water, H2O




          7. Which of the following gases has the lowest density?
             a. methane, CH4
             b. ethane, CH3CH3
             c. propane, CH3CH2CH3
             d. butane, CH3CH2CH2CH3
          8. Which of the following substances has the strongest London forces?
             a. methane, CH4
             b. ethane, CH3CH3
             c. propane, CH3CH2CH3
             d. butane, CH3CH2CH2CH3
          Which of the following will have stronger London forces.
                                                                          a. H2
                                                                          b. He
                                                                          c. Ne
                                                                           d. Kr
              Which of the following molecules shows the greatest effects of
          15.
              hydrogen bonding?
             a. H2S
             b. CH4
             c. NH3
             d. H2O



1. The phase change from liquid to gas is known as _____.

    A. condensation

    B. evaporation
     C. sublimation

     D. melting

     E. freezing



2. The weakest type of forces between particles (intermolecular forces)
   are _____.

     A. metallic bonds

     B. dipole-dipole forces

     C. ionic bonds

     D. London dispersion forces

     E. covalent bonds



3. Substances in which the intermolecular forces are very weak are
   usually in the _____ phase at room temperature.

     A. gas

     B. plasma

     C. aqueous

     D. liquid

     E. solid



4. The type of intermolecular forces (forces of attraction between the
   particles) present in elemental iodine are _____.

     A. dipole-dipole forces

     B. ionic bonds

     C. covalent bonds

     D. metallic bonds

     E. London dispersion forces



5. The type of intermolecular forces (forces between the particles)
   present in solid mercury are _____.

     A. metallic bonds

     B. London dispersion forces

     C. ionic bonds
     D. dipole-dipole forces

     E. covalent bonds



6. The type of intermolecular forces (attractive forces between the
   particles) present in potassium nitrate are _____.

     A. covalent bonds

     B. ionic bonds

     C. London dispersion forces

     D. dipole-dipole forces

     E. metallic bonds



7. The type of intermolecular forces (attractive forces between the
   particles) present in magnesium bromide are _____.

     A. dipole-dipole forces

     B. covalent bonds

     C. ionic bonds

     D. metallic bonds

     E. London dispersion forces



8. The type of intermolecular forces (attractive forces between particles)
   in solid water are _____.

     A. metallic bonds

     B. ionic bonds

     C. covalent bonds

     D. dipole-dipole (hydrogen-bonding) forces

     E. London dispersion forces



9. _____ is an example of an ionic solid.

     A. Silver chloride

     B. Silver

     C. Carbon tetrachloride
     D. Carbon dioxide

     E. Carbon



10. Solid _____ is an example of an atomic solid.

     A. water

     B. oxygen

     C. neon

     D. cesium iodide

     E. carbon monoxide



11. _____ is an example of a molecular solid.

     A. Aluminum

     B. Sodium chloride

     C. Sucrose (C12H22O11)

     D. Sodium

     E. Diamond



12. "Atoms in a sea of electrons" describes _____ bonding.

     A. covalent

     B. ionic

     C. hydrogen

     D. metallic

     E. atomic



13. The _____ is the amount of heat necessary to change one mole of
    liquid to one mole of gas.

     A. molar heat of vaporization

     B. molar heat of fusion

     C. specific heat capacity

     D. boiling temperature

     E. melting energy
14. Water is most dense in its _____ phase.

    A. liquid

    B. solid

    C. gaseous

    D. aqueous

    E. plasma




7. Identify the strongest intermolecular force operating in the condensed phases of the
following substances. Fully explain how you determined this.

a. Cl2 London dispersion forces               b. CO          Dipole-dipole forces

The Cl-Cl bond is nonpolar so the             The C-O bond is polar so the molecule is
molecule is nonpolar. Non polar               polar. Polar molecules have dipole-dipole
molecules have only London dispersion         forces. They also have London dispersion
forces operating in the substance.            forces, but dipole-dipole forces are stronger.

c. SO2 Dipole-dipole forces                   d. CH2Cl2       Dipole-dipole forces

SO2 is a bent, polar molecule. The            The strongest intermolecular force in a polar
strongest intermolecular force in a polar     molecule that cannot form hydrogen bonds is
molecule is the dipole-dipole force           the dipole-dipole force

e. HF Hydrogen bonding forces                 g. CH3-O-CH3 Dipole-dipole forces

Molecules that have hydrogen attached to      The hydrogen atoms are not bonded to the
an O, N, or F can form hydrogen bonds.        oxygen, so this molecule cannot form
These are the strongest of the                hydrogen bonds. It is polar, so it will have
intermolecular forces.                        dipole-dipole forces.




8. Predict the order of the boiling points of the following substances. Rank them from
lowest boiling to highest boiling. Explain your reasoning.

a. CH3OH, CH3F, F2
Boiling point order: F2 < CH3F < CH3OH

Boiling points increase as the strength of the intermolecular forces increase. F2 is non-
polar, so only dispersion forces are present. CH3F is polar, so it will experience stronger
dipole-dipole forces. CH3OH can hydrogen bond, these are the strongest of the
intermolecular forces.


b. CCl4, CBr4, CI4

Boiling point order: CCl4 < CBr4 < CI4

All three compounds are non-polar, so only dispersion forces are involved. The strength
of the dispersion forces increase as the molar mass increases, so the boiling points will
increase as the molar mass increases.




9. For each pair of substance identify the substance that is likely to have the higher vapor
pressure. Explain your reasoning.

a. CO2 or SO2

CO2 will have the higher vapor pressure. Vapor pressure tends to decrease as the strength
of the intermolecular forces increase. Carbon dioxide is non-polar (dispersion forces
only). Sulfur dioxide is polar (dipole-dipole forces are present).


b. CH3OH or CH3-O-CH3

CH3OCH3 will have the higher vapor pressure. Vapor pressure tends to decrease as the
strength of the intermolecular forces increase. CH3OH can hydrogen bond. CH3OCH3 is
polar (bent shape around the oxygen), so dipole-dipole forces are the strongest forces in
this compound.

				
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