Question

(C) Water is less dense as a solid than as a liquid. (D) What has strong hydrogen bonding interaction between molecules, which allow it to have a high heat evaporation. (E) All of the listed properties of water make life possible. Aspartic acid is a weak amino, its structure is shown below. 10(60) 1) Draw a possible titration curve (pH versus [OH^-]) for 1 M aspartic solution. Indicate the pK_as in the graph (pK_1 = 2.1, pK_2 = 3.9 and pK_3 = 9.8). 2) What are the buffer range(s) if aspartic acid is used as a buffer? 3) Determine its pH value: For the following molecules, rank the molecules with high to low boiling points and explain why? H_2O CH_2OH (methanol), and CH_4 (methane)

Answer 1

For aspartic acid amino acid

1) Drawn below is a representation of titration curve with OH-.

12 pKa3 9.8 10 pH 6 pKa2 3.9 4 pKa1 2.1 0.5 1.5 Equivalent of OH-

2) Buffer regions for the amino acid would be, between pH 0 to 3.0, above 3.0 to 6.8

3) pI for aspartic acid = (2.1 + 3.9)/2 = 3.0