Question

Henderson-Hasselbach equation: pH- pKa log (IA-|/IHA]) 1. Phosphate buffer is a mixture of KH2PO4 and K2HPO4. Note that KH2PO4 has one additional proton. The pKa of the acid is 6.8. Use the Henderson-Hasselbach equation (above) to calculate the ratio of [K2HPO41[KH2PO4] needed to make a solution that is pH 7.2 2. To make a solution that is 0.2 M phosphate, the concentration of KH2PO4 and K2HPO4 must add up to 0.2 M. Use the ratio you calculated above, and the equations below to calculate the number of grams needed to make 200 ml of 0.2 M phosphate buffer. (HINT: you can solve for the concentrations of each, since you have two equations and two unknowns. Once you have the concentrations, figure out how many grams of each you need to make 200 ml) [K2HPO4]/[KH2PO4]-? (answer from above) [KH2PO4] +[K2HPO4] 0.2 M 3. How many grams of mannitol (MW 182.17) is needed to make 200 ml of 0.3 M mannitol?

Answer 1

CHAl 2 = 0014 Co -'. g=-56x200 11.2 0-14- 200 14 200

ci naNe emembey «Hof mannitol ot son. Civen - 00 12 -10. 93 m m at manni
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