Chapter 4, Problem 4.74PAE

One way of determining blood alcohol levels is by performing a titration on a sample of blood. In this process, the alcohol from the blood is oxidized by dichromate ions (Cr₂O₇^2-) according to the following net ionic equation:

   ${\text{C}}_{\text{2}}{\text{H}}_{\text{5}}\text{OH }+{\text{ 2 Cr}}_{\text{2}}{\text{O}}_{\text{7}}{}^{\text{2}-}+{\text{ 16 H}}^{+}\to {\text{ 2 CO}}_{\text{2}}+{\text{ 4 Cr}}^{\text{3}+}+{\text{ 11 H}}_{\text{2}}\text{O}$

A 10.00-g sample of blood was drawn from a patient, and 13.77 mL of 0.02538 M K₂Cr₂O₇ was required to titrate the alcohol. What was the patient’s blood alcohol level? (See the previous problem for definition of blood alcohol level. K₂Cr₂O₇ is a strong electrolyte, so it dissociates completely in solution.)