[Ashley91]

Hey everybody, I got a little behind in Chemistry and have been trying to get caught up, I have a homework assignment due tonight but cant seem to find answers to these questions anywhere.  Any help would be much appreciated.

1. What are the important intermolecular forces acting in NaOH?

London dispersion forces only
only dipole-dipole interactions and H-bonding
dipole-dipole interactions and London dispersion forces
H-bonding, dipole-dipole interactions and London dispersion forces
ionic bonding

2. A covalent crystal differs from an ionic crystal in that

    only one of them is a poor electrical conductor.
    only one of them has bonding that involves overlap of electronic orbitals.
    only one of them possesses atomic order.
    only one of them has high melting points.
    only one of them is hard.

3. As the intermolecular attractive forces between molecules increase in magnitude, which of the following will increase in magnitude?

(a) vapor pressure
(b) heat of vaporization
(c) boiling point

    only a
    only b
    a and c
    b and c
    all three will increase

4. The slope of the solid/liquid equilibrium line in the H2O phase diagram has a negative slope (melting point decreases with increasing pressure) because ______.


    the solid tends to sublime at high pressure.
    the solid is less dense than the liquid.
    the liquid is compressible but the solid is not.
    melting is exothermic and tends to occur at high pressure.
    at pressures above the triple point, only the liquid is stable.

[Ashley91]

Or could you verify if what I got is correct.  Ive worked on these and a bunch other for several hours and this is a last resort, but I did try them myself first.  For number 1 I got its ionic bonding, however im confused as thats not an intermolecular force, from what I know.  Number 2 I got that only one overlaps electronic orbitals, which is covalent.  Number 3 I got that both B and C are correct.  The last one I am pretty stumped on and not sure where to even begin. 

Once again any help or verification would be greatly appreciated!

[rabolisk]

You're right for 1, 2, and 3. For 1, I assume they mean solid NaOH, and not aqueous NaOH. You are right that ionic bonds are not "intermolecular" forces, but they are what keeps the Na+ and OH- ions together. In that sense, their function is the same as the intermolecular forces that keep molecules together in molecular solids (e.g. ice).

For 4, what answers can you eliminate based on chemical intuition?