Chlorendic acid [1,4,5,6,7,7-hexachlorobicyclo-(2,2,1)-hept-5-ene-2,3-dicarboxylicacid] is a highly chlorinated compound used as a flame retardant. It is a diprotic acid with pKa,1=3.1 and pKa,2=4.6. Chlorendic acid inhibits the growth of the alga Chlorella at pH 3.5, but not at pH 5 or pH 7.5 (Hendrix etal., 1983)
a) Using graphical techniques, which form of chlorendic acid (neutral, mono-anionic, or di-anionic) is not responsible for the inhibitory effect?
b) Using graphical techniques, calculate the distribution (i.e., the fraction) of chlorendic acid ( in uncharged, mono-anionic and di-anionic forms) at pH 3.5,5.0, and 7.5.