Tumambing,Vernice Kristine M.

2010-28996

Experiment 1

Solubility Behavior of Organic Compounds

1. State what types of intermolecular forces are present in solutions formed due to intermolecular

attractions between the solute and the solvent.

Based on the results of the experiment, only three organic test compounds (sucrose, acetone and

ethyl alcohol) were soluble in water. It implies that the hydrogen bonding in the water molecules

and the dipole-dipole interactions among the polar solute molecules were replaced by hydrogen

bonding between the solute and the solvent. Of the three test compounds, the two, which are

acetone and ethyl alcohol respectively, are soluble with ether making the test compounds non-

polar since there is a non-polar compound. Ether was able to dissolve acetone and ethyl alcohol

by London Dispersion Force.

To sum it up:

Acetone-H2O London dispersion, dipole-dipole, H-bonding Ethyl alcohol-H2O London dispersion, dipole-dipole, H-bonding Sucrose-H2O London dispersion, dipole-dipole, H-bonding Acetone-Ether London dispersion Ethyl alcohol-Ether London dispersion

2. Write the balanced chemical equations for solute-solvent combinations that are formed due to

chemical reactions

Benzoic acid - NaOH C6H5COOH(s) + OH-(aq) C6H5COO-(aq) + H2O(l) Benzoic acid - NaHCO3 C6H5COOH(s) + HCO3-(aq) C6H5COO-(aq) + H2CO3(aq) Phenol - NaOH C6H5OH(aq) + OH-(aq) C6H5O-(aq) + H2O(l) Aniline - HCl C6H5NH2(aq) + H+(aq) C6H5NH3+(aq) Benzyl Alcohol - H2SO4 C6H5CH2OH(aq) + 2H2SO4(aq) C6H5CH2OSO3H(s) + HSO4-(aq) + H3O+(aq) Benzaldehyde - H2SO4 C6H5COH(aq) + 2H2SO4(aq) C6H5COSO3H(S) + HSO4-(aq) + H3O+(aq)

3. On the basis of solubility behavior, show how each of the following pairs of compounds may be distinguished from the other. a. CH3NH2 and CH3(CH2)5CH2NH2

CH3NH2 is a small, polar molecule and can hydrogen bond with water. CH3(CH2)5CH2NH2 can also hydrogen bond with water via the amino group but is much less polar due to the presence of a much longer, non-polar, hydrocarbon chain.

water soluble insoluble

b. CH3CHO and HOCH2CHO

CH3CHO is small and polar, and can hydrogen bond with water via the O on the C=O group. It is both soluble on water and ether due to its single polar unit and a short non-polar chain.

. water

soluble insoluble

soluble insoluble

c. Benzylamine and benzyl alcohol

Benzylamine is soluble in 5% HCl because of its NH2 functional group while benzyl alcohol is insoluble in 5% HCl and could be dissolved by making it react with concentrated sulfuric acid.

water soluble insoluble soluble insoluble References:

Organic Chemistry Laboratory Manual. Institute of Chemistry, UP Diliman. 2008. http://www.wpi.edu/Academics/Depts/Chemistry/Courses/General/concept6.html#sec6-5 http://www.elmhurst.edu/~chm/vchembook/170solutions.html

insoluble soluble

water

organic compounds

+ ether + 5% NaOH

organic compounds

CH3NH2 CH3(CH2)5CH2NH2

organic compounds

+ ether

CH3CHO HOCH2CHO

organic compounds

benzyl alcohol + 5% HCl

benzylamine