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A 2.00-mL solution of apotransferrin was titrated as illustrated in Figure 17-10. It
Chapter 17, Problem 17-20(choose chapter or problem)
A 2.00-mL solution of apotransferrin was titrated as illustrated in Figure 17-10. It required 163 L of 1.43 mM ferric nitrilotriacetate to reach the end point. (a) Why does the slope of the absorbance-versus-volume graph change abruptly at the equivalence point? (b) How many moles of Fe(III) (= ferric nitrilotriacetate) were required to reach the end point? (c) Each apotransferrin molecule binds two ferric ions. Find the concentration of apotransferrin in the 2.00-mL solution.
Questions & Answers
QUESTION:
A 2.00-mL solution of apotransferrin was titrated as illustrated in Figure 17-10. It required 163 L of 1.43 mM ferric nitrilotriacetate to reach the end point. (a) Why does the slope of the absorbance-versus-volume graph change abruptly at the equivalence point? (b) How many moles of Fe(III) (= ferric nitrilotriacetate) were required to reach the end point? (c) Each apotransferrin molecule binds two ferric ions. Find the concentration of apotransferrin in the 2.00-mL solution.
ANSWER:Step 1 of 3
a) The slope of the absorbance versus volume graph changes abruptly at the equivalence point because before the equivalence point Fe binds to a protein and forms a red complex, so the absorbance increases. After the equivalence point, there are no binding sites.