pka is 7.21, Assigned pH: ____6.8__________ . prepare 50 mL of a
50 mM buffer at your assigned pH, calculate the ratios of the
monobasic and dibasic species you will be using with the
Henderson-Hasselbalch equation. Ratios: Monobasic species:
______________ Dibasic species: ______________ Volumes: Monobasic
species: ______________ Dibasic species: ______________
Part 1
Calculate the amount (in millimoles) of protonated and unprotonated HEPES in 25 mL of 50 mM HEPES at pH 7.7 (the pKa of HEPES is 7.47)
Part 2
To adjust the pH of the HEPES solution in problem 7, 1mL of 50mM NaOH was added. Calculate the amount (in millimoles) of protonated and unprotonated HEPES. What is the pH after the addition of NaOH?
You must make a sodium phosphate buffer (500 ml at 50 mM) at a pH
value of 6.8. Assume that the pKa is 7.0. MW oh NaH2PO4 = 138g/mol.
MW of NaH2PO4 = 268 g/mol
Show the weak acid base reaction with proper
structures. use the Henderson/ Hasselbalch relationship to obtain
molarity of each species. Calculate the grams of each salt
required.
You have 200 ml of 0.1M HEPES buffer, pH 7.5. You add 2 ml of
0.4M HCl. The pKa of HEPES is 7.5.
a) what will the resulting pH be?
b) what would the pH be if no HEPES were present (that is, you
mixed water and HCl)?
Using a 0.20 M phosphate buffer with a pH of 7.4, you add 0.71
mL of 0.54 M HCl to 59 mL of the buffer. What is the new pH of the
solution? (Enter your answer to three significant figures.)
Using a 0.20 M phosphate buffer with a pH of 7.4, you add 0.71
mL of 0.54 M NaOH to 59 mL of the buffer. What is the new pH of the
solution (Enter your answer to three significant figures.)
Describe in detail how you would preapre 100 mL of 0.15 M HEPES
buffer at pH 7.30 at room temperature. The pKa of HEPES is 7.55.
Prepare the buffer by using the free acid form,
and then titrate with a 1.00 M strong acid/base until the desired
pH is reached
Hints:
- Calculate the amount of HEPES free acid that you need to
prepare 100 mL of 0.100 M solution using the molecular weight of
238.3 g/mol
- Use the...