| MadSci Network: Botany |
In acid-base chemistry, a one normal solution has one equivalent or one mole of hydrogen or hydroxyl ions per liter. Thus, one normal NaOH is the same as one molar NaOH because each NaOH molecule has just one hydroxyl ion. One molar sulfuric acid would be two normal because there are two hydrogen ions per molecule of sulfuric acid. The main organic acid that accumulates in CAM plants is malic acid. It has two hydrogen ions per molecule that must be titrated. Thus, if you need 10 millimoles of NaOH to titrate your sample, that would correspond to just 5 millimoles of malic acid. The first reference has directions for titrating malic acid. The second reference has directions for titrating CAM leaves for organic acids. References Determination of titratable acidity in apple juice Friend, Douglas J. C. 1990. Plant eco-physiology: Experiments on Crassulacean acid metabolism, using minimal equipment. American Biology Teacher 52:358-63.
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