A quantity of 432 mg of an amino acid with a neutral side chain consumes 7.39 mE
ID: 820746 • Letter: A
Question
A quantity of 432 mg of an amino acid with a neutral side chain consumes 7.39 mEq of acid and base in the titration range of 0.8 to 12.0. What is the name of the amino acid?
Okay. So, how we were instructed to solve problems of this sort in lab was to find the mass of the unknown in grams--given here as 432 mg or 0.432 g--and then find the number of moles of acid or base used to titrate the solution to the amino acid's pI. However, I'm having trouble seeing how the number of moles could be found from the information given. Would I just divide 7.39 mEq (or would it be 0.00739 Eq?) by two to get my answer, and then divide the grams of unknown by that number to get the molecular weight of the unknown? In other words...
0.00739 Eq / 2 = 0.003695 mol
MW Unknown = 0.432 g / 0.003695 mol = 117 g/mol
...making the unknown amino acid...valine??? Or possibly proline?
PLEASE HELP!!!
Explanation / Answer
What you are Doing is the right procedure to do such type of question , now since you've got the moleculer weight of the compound , you'll need to know which compund (valine or proline ) has the moleculer weight closer to what you got , As the moleculer weight of valine is 117.151 g and proline is 115.13 g, so your compound is Ammino acid valine. I hope this helps.