Solutions, Molarity and Intermolecular Forces Video Lessons

Concept: Solutions and Molarity.

# Problem: In flushing and cleaning columns used in liquid chromatography to remove adsorbed contaminants, a series of solvents is used. Hexane (C6H14), chloroform (CHCl3), methanol (CH3OH), and water are passed through the column in that order. Rationalize the order in terms of intermolecular forces and the mutual solubility (miscibility) of the solvents.

###### FREE Expert Solution

For this problem, we are being asked to rationalize the order in terms of intermolecular forces and the mutual solubility (miscibility) of the solvents

Recall that there are several types of intermolecular forces:

1. Ion-dipole interaction – occurs between an ion and a polar covalent compound

2. Hydrogen bonding – occurs in compounds where hydrogen is directly connected to an electronegative element such as N, O, or F

3. Dipole-dipole interaction – occurs between two polar covalent compounds

4. Induced-dipole interaction – occurs when a nonpolar compound interacts with a polar compound

5. Dispersion forces – occurs in all compounds. This is the primary intermolecular force exhibited by nonpolar compounds.

For C6H14 → Hydrocarbon → Limited on having Dispersion forces as its IMF

For CHCl3: The total number of valence electrons present in CH3Cl is:

Group            Valence Electrons

C         4A                   1 × 4 e = 4 e

H         1A                   3 × 1 e = 3 e

Cl         7A                  1 × 7 e = 7 e

Total:  14 valence e

The Lewis structure of CH3Cl is:

Since C-Cl bond creates a dipole, this molecule is capable of dipole-dipole and dispersion forces as its IMF

For CH3OH: The total number of valence electrons present in CH3OH is:

Group            Valence Electrons

C         4A                   1 × 4 e = 4 e

H         1A                   4 × 1 e = 4 e

O         6A                  1 × 6 e = 6 e

Total:  14 valence e

89% (75 ratings)
###### Problem Details

In flushing and cleaning columns used in liquid chromatography to remove adsorbed contaminants, a series of solvents is used. Hexane (C6H14), chloroform (CHCl3), methanol (CH3OH), and water are passed through the column in that order. Rationalize the order in terms of intermolecular forces and the mutual solubility (miscibility) of the solvents.