A forensic chemist analyzed a sample of cocaine and determined it was adulterated with borax (Na2B4O7), a component of some detergents. In order to determine the purity of cocaine in the sample, the chemist dissolved 0.582g of adulterated cocaine with water to a final volume of 25.00 mL in a volumetric flask. The titration (reaction show below) if a 10.00mL aliquot of this solution reached the endpoint with 21.25 mL of hydrochloride acid 50.0 mM. What is the percent of cocaine in the sample?
Balanced chemical equation: Na2B4O7 (aq) + 5H2O (l) + 2HCL (aq) —> 4B(OH)3 (aq) + 2NaCl (aq)
Note: any reaction between HCL and cocaine would happen after all borax is consumed, so the endpoint represents the titration of just borax