A 500 mg dietary supplement of L-lysine (an amino acid,146.2 g/mol)required 68.4 mL of 0.100 M NaOH to reach the end point.How many hydrogen ions were removed for each L-lysine molecule in this titration?

Question

Quizplus · Accepted Answer

L-lysine has two acidic hydrogen ions that can be removed by NaOH. The molarity of NaOH and the volume used in the titration can be used to calculate the amount of moles of NaOH used. Since each mole of NaOH removes two moles of hydrogen ions from L-lysine, we can obtain the number of hydrogen ions removed by dividing the moles of NaOH used by two. Therefore, (0.100 mol/L) x (0.0684 L) / 2 = 0.000342 mol of hydrogen ions were removed. Since the supplement is 500 mg, which is equal to 3.417 x 10^-3 mol, then the ratio of hydrogen ions removed per L-lysine molecule is (0.000342 mol) / (3.417 x 10^-3 mol) = 2. Therefore, the best choice is B.

A 500 Mg Dietary Supplement of L-Lysine (An Amino Acid,146