Describe how you would prepare 1.50 L of a 0.5 M phosphate buffer with a pH of 7
ID: 828702 • Letter: D
Question
Describe how you would prepare 1.50 L of a 0.5 M phosphate buffer with a pH of 7.5?
If 5.0 mL of 0.15 M HCl is added to 750 ML of your buffer (taken from preparing 1.50 L of a 0.5 M phosphate buffer with a pH of 7.50), what will your new pH be?
If 10.0 mL of 0.15 M HCl is added to 750 ML of your buffer (taken from preparing 1.50 L of a 0.5 M phosphate buffer with a pH of 7.50), what will your new pH be?
*** I have used the Handerson-Hasselbach equation and got ansewers 86.4g HPO4, and 34.6g H2PO4, I ma lost for the last 2 questions....
Explanation / Answer
New pH = pKa + log (Salt - X / Acid + X)
where X = HCl added
and
pH = pKa + log (Salt + Y / Acid - Y)
where Y = base added
NOTE: All should have the same units. For eg. if salt and acid ate in moles , then X or Y should also be in moles