Aprotein was previously determined to contain 15.7 wt% nitrogen. a 647 m aliquot of a solution containing the protein was digested in boiling sulfuric acid. the solution was made basic and the liberated nh3 was collected in 10.00 ml of 0.0388 m hci. 3.83 ml of 0.0196 m naoh was required to react with the excess, unreacted hcl. calculate the protein concentration of the solution in units of milligrams per milliliter. number 0 mg protein ml solution

431.38 mg protein / mL

Explanation:

This is an example of the Kjeldahl method, for nitrogen determination. All nitrogen atoms in the protein were converted to NH₃ which then reacted with a known excess of HCl. This excess was later quantified via titration with NaOH.

First we calculate the total amount of H⁺ moles from HCl:

Now we calculate the excess moles of H⁺ (the moles that didn't react with NH₃ from the protein), from the titration with NaOH:

Now we substract the moles of H⁺ that reacted with NaOH, from the total number of moles, and the result is the moles of H⁺ that reacted with NH₃ from the protein:

With the moles of NH₃ we know the moles of N, then we can calculate the mass of N present in the aliquot:

From the exercise we're given the concentration of N in the protein, so now we calculate the mass of protein:

Finally we calculate the protein concentration in mg/mL, assuming your question is in 647 μL, we first convert that value into mL:

well in order to answer this question you have to provide more information < 3

the answer to this question is 3.