Grand Canyon University Phosphate Buffered Saline Solution Questions
I’m studying and need help with a Chemistry question to help me learn.
A phosphate-buffered saline solution is used in biological research because it maintains a particular pH, while also matching the number of ions in human blood. This solution is prepared by dissolving the following masses of these component into 1.00 L of deionized water:
|
Component |
Mass (g) |
|
NaCl |
8.00 |
|
KCl |
0.200 |
|
Na2HPO4 |
1.44 |
|
KH2PO4 |
0.240 |
The Ka for H2PO4¯ is 6.25 x 10-8. Answer the following questions about the phosphate-buffered saline solution.
1.(2 pt) Determine the total concentration, in moles per liter, for Na+ in the phosphate-buffered saline solution.
2.(2 pt) Determine the total concentration, in moles per liter, for K+ in the phosphate-buffered saline solution.
3.(2 pt) Determine the total concentration, in moles per liter, for Cl¯ in the phosphate-buffered saline solution.
4.(2 pt) Determine the concentration, in moles per liter, for HPO42¯ in the phosphate-buffered saline solution.
5.(2 pt) Determine the concentration, in moles per liter, for H2PO4¯ in the phosphate-buffered saline solution.
6.(4 pt) Do the NaCl or KCl contribute to the pH of the solution? Explain your reasoning.
7.(3 pt) What is the pH of the phosphate-buffered saline solution?
8.(4 pt) What color would the solution be if red cabbage juice was added? Explain your reasoning.
9.(4 pt) Write a reaction that shows how added strong acid (H+) will be absorbed by the phosphatebuffered saline solution, maintaining the pH.
10.(4 pt) Write a reaction that shows how added strong base (OH¯) will be absorbed by the phosphate-buffered saline solution, maintaining the pH.
11.(3 pt) You accidentally drop 0.0500 g of NaOH into your 1.00 L of prepared phosphate-buffered saline solution. What is the pH of the solution after this accident?
12.(3 pt) You accidentally drop 5.00 g of NaOH into your 1.00 L of prepared phosphate-buffered saline solution. What is the pH of the solution after this accident?
13.(3 pt) You are making your phosphate-buffered saline solution in a container that had a little solution in it. You assumed that the solution was pure water, but it turns out it was 5.00 mL of 1.00 M HNO3. What is the pH of the phosphate-buffered saline solution that you prepared? Hint: your final total volume is the sum of the 1.00 L phosphate-buffered saline solution and the 5.00 mL of the HNO3.
14.(4 pt) You realize that you added 0.500 g of KCl to your solution instead of 0.200 g of KCl. Do you expect the pH to be impacted by the additional KCl in the solution?
15.(4 pt) Will the pH of the solution change if the temperature of the solution is increased? Explain your reasoning.
16.(4 pt) Why are both K+ and Na+ important for a biological buffer?
