Hydrogen Phosphate Buffer Systems

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Experiment 8: Hydrogen Phosphate Buffer Systems

Purpose
The purpose of the lab was to create a buffer solution and observe the capacity of the phosphate buffer system. Also, the experiment was meant to provide experience with the calculations and mathematics involved in creating the buffer solution. Finally, the lab was designed to provide an insight and appreciation for the necessity and complexity of buffers in our physiology and in the environment.

Procedure
No deviations were made from the procedure in the online lab manual. A hydrogen phosphate buffer at pH 7 was used. 60.97g of KH2PO4 (acid) and 20.42g of K2HPO4 (base) were weighed out for use.

Data
25mL of DIH2O in 100mL beaker had pH = 7.40. After one drop of 0.50M HCl was added to the beaker, pH dropped to 3.08, and the change in pH was -4.32. After one drop of 0.50M NaOH, the pH jumped to 10.3, and the change was 2.9. pH of 25mL of created buffer solution = 6.15

Volume of HCl Added to 25mL of Buffer Solution| pH| Concentration of Acid After Addition | Concentration of Conjugate Base After Addition| 0mL| 6.15| 0.378M (initial)| 0.122M (initial)|
1mL| 6.02| 0.403M| 0.0968M|
2mL| 5.87| 0.427M| 0.0726M|
3mL| 5.67| 0.451M| 0.0483M|
4mL| 5.46| 0.468M| 0.0310M|

Volume of NaOH Added to 25mL of Buffer Solution| pH| Concentration of Acid After Addition| Concentration of Conjugate Base After Addition| 0mL| 6.15| 0.378M (initial)| 0.122M (initial)|
1mL| 6.22| 0.362M| 0.138M|
2mL| 6.31| 0.341M| 0.159M|
3mL| 6.42| 0.312M| 0.188M|
4mL| 6.50| 0.290M| 0.210M|
5mL| 6.59| 0.264M| 0.236M|
6mL| 6.68| 0.238M| 0.262M|

Volume of HCl Added to 12.5mL of Buffer + 12.5mL of DIH2O| pH| Concentration of Acid After Addition| Concentration of Conjugate Base After Addition| 0mL| 6.32| 0.189M| 0.0610M|
1mL| 5.94| 0.208M| 0.0417M|
2mL| 5.45| 0.235M| 0.0152M|

2H2O(l) (and ) ((H3O)^+)(aq) + [OH]^- (aq)

Volume...
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