Question

Draw the structures of: water, glycerol, ethylene glycol, acetone, hexane, and methanol. Name and briefly describe the intermolecular attractive forces (IMAF) you would expect to find for each of the drawn structures. Be sure to include the viscosity and density for ethylene glycol (also called glycol), glycerol (also called glycerine) and the denisty of mineral oil (also called paraffin oil)--and also, include what the denisties are of acetone, hexane, methnol, and water. Thanks so much for the explaination to help me with this lab! Im so confused and need some visual and written explaination.

Answer 1

1. Hydrogen bonding: The weak electrostatic force of attraction between highly electronegative atoms like F,O,N and H bonded to one of these electronegative atom in same/different molecule.

1. Hence Water, glycol, glycerol, and methanol show H-Bonding and it is only responsible for molecular association in compound.
2. As no. of H- Bonding groups increases molecular association becomes stronger. This causes the two properties of compound to increase viz. Viscosity and density.

1. Viscosity: The ability to resist the flow is termed as viscosity. As H-bonding increases, molecular association increases- hence molecules offer more resistance to flow and hence viscosity increases.
2. Among water, glycol, glycerol, and methanol, glycerol being having largest number of OH groups and hence shows maximum H-bonding and hence the most viscous. So the trend of viscosity is glycerin > Glycol > water > methanol.
3. Density: It is the mass/volume or simply we can say no.of molecule/volume (mass and no. of molecule are in direct proportion). As molecular association increases density increase. So same trend as in viscosity will observed in density also.

1. Dipole-Dipole interaction: The compound containing partially polar bond like C=O in acetone shows dipole-dipole interaction and associates. But this association is weaker than by H-Bonding. Hence viscosity and density of acetone will be less than above 4 compounds.
2. Induced dipole-induced dipole interaction or London forces: The non-polar molecules show this kind of interactions. e.g. hexane

1. The cause for dipole induction is….. The electrons round the nucleus are in continuous motion. For the instance they get one sided and make nucleus naked and this induces temporary dipole formation (nucleus as +ve and electrons as –ve dipole).
2. This is the weakest interaction among the all possible interactions.
3. Hence lowest molecular association they offer and hence the viscosity and density of hexane is lowest among the all.

1. Finally the trend for viscosity and density is Glycerin > Glycol > Water > Methanol > Acetone > Hexane.