The elemental composition of the humic and fulvic acid fractions of an Elliott soil (an Aquic Argiudoll) is given in the table below. Answer the following (Text 4.11, 25 pts):

Elemental Content (in g kg-1) of Humic and Fulvic Acids Extracted from an Elliot Soil Compound C H O N S:

Humic Acid: C = 581, H = 36.8, O = 341, N = 41.4, S = 4.4

Fulvic Acid: C = 506, H = 37.7, O = 437, N = 27.2, S = 5.6

a. Calculate the molar O/C and H/C of the humic and fulvic acids and compare your results to the O/C and H/C of acetic acid (a simple aliphatic acid) and benzoic acid (a simple aromatic acid). Discuss your findings.

b. Calculate the maximum potential negative charge that can be created on the fulvic and humic acids, assuming that the oxygen content is assigned to carboxyl groups.

c. Express your results in cmolc kg ⁻¹ . Compare your results to the cation exchange capacity values attributed to smectites and vermiculites.

d. Calculate the maximum potential positive charge that can be created on the fulvic and humic acids, assuming that the nitrogen content is assigned to amino groups. Express your results in cmolc kg ⁻¹ .