4. Draw a representation of how you might expect a sample of H,0 molecules to arrange themselves. What type of intermolecular forces exists between water molecules? 5. Look up the structure of DNA and identify the intermolecular forces that support the double helical shape of DNA.

A solution of benzoic acid in benzene has a freezing point of 3.1 C and a boiling point of 82.6 C. (The freezing point of pure benzene is 5.50 C, and its boiling point is 80.1 C) The structure of benzoic acid is Benzoic acid, C6H5CO2H What can you conclude about the state of the benzoic acid molecules at the two different temperatures? Recall the discussion of hydrogen bonding in Section 11.3.

Figure 4.1 is a cartoon depiction of liquid water at the molecular level. a. (E) Label at least one representation of a covalent bond and at least one representation of anintermolecular force found in Figure 4.1. b. (E) Which are shorter and stronger: covalent bonds p intermolecular forces [circle one]?

Consider the following formulas for n-pentane and neopentane: CH3CH2CH2CH2CH3 -Pentane Both compounds have the same overall formula (C5H12, molar mass = 72.15 g/mol), yet n-pentane boils at 36.2C whereas neopentane boils at 9.5C. Rationalize the differences in the boiling points between these two nonpolar compounds.

What are intermolecular forces? How do they differ from intramolecular forces? What are dipole-dipole forces? How do typical dipole-dipole forces differ from hydrogen bonding interactions? In what ways are they similar? What are London dispersion forces? How do typical London dispersion forces differ from dipole-dipole forces? In what ways are they similar? Describe the relationship between molecular size and strength of London dispersion forces. Place the major types of intermolecular forces in order of increasing strength. Is there some overlap? That is, can the strongest London dispersion forces be greater than some dipole-dipole forces? Give an example of such an instance.