SI week 2 wed.pdf - SI CHEM 3650 – 1/12/2022 SI Leader:...

SI CHEM 3650 – 1/12/2022
SI Leader: Ethan DePry
Warm up
Question 1. You are trying to create a buffer of pH = 2. To do this, you decide to use phosphoric
acid H
3
PO
4
( pKa=2.15 ).
a. Write the chemical formula for each species present in this buffer
Acid:
Conjugate base:
b. Write out the Henderson-Hasselbalch equation
c. Using the equation you just wrote, calculate the conjugate base to acid ratio required to
create the desired buffer.
e. Phosphoric acid is a polyprotic acid and has 3 ionizable protons each with their own pKa
values. pK
1
=2.15 pKa
2
=6.82 pKa
3
=12.38
Draw the titration curve for phosphoric acid. Be sure to account for all 3 equivalence
points. Be sure to label each axis.

Main Activity