Oxalic acid is the first in the series of dicarboxylic acids (HOOC-COOH, H2C2O4). It occurs naturally in many plants. Oxalic acid content is high in the leaves of rhubarb (we don't eat the leaves because they are poisonous). Calculate the pH of a 0.100 M oxalic acid solution. Ka1 = 5.6x10-2, Ka2 = 5.4x10-5