1(a) The table presented here shows the stoichiometric coefficients in a "CHONS" chemical formula for the water-extractable fraction of humus averaged for 10 U.S. soils representing a broad range of organic C content, climate, and texture, but all of them having C:N10 to 12 and pH 6 to 7. Calculate the H/C and O/C ratios based on the average chemical formula. Plot your results in a van Krevelen diagram to characterize the soluble organic matter. What group/s of compounds dominate water-extractable fraction of humus? Calculate H/C and O/C ratios for several aliphatic and aromatic low molecular weight organic acids (Use at least three of each type). Are SOM compounds largely aliphatic or aromatic? (b) Estimate the maximum charge in mmolckg1 for the water-extractable fraction of humus assuming that all of the oxygen content can be assigned to carboxylic acids that undergo the dissociation reaction: RCOOH=RCOO+H+