Reference no: EM132439615

Please help me with the questions.

1. You are asked to prepare 1L buffer, 0.3M, pH 6. Please choose one of the following chemicals that would be the best choice for preparing your buffer and briefly explain the rationale behind it.

Chemical pKa

Citric acid 3.13

Succinic acid 3.75

Acetic acid 4.80

MES 6.09

Carbonic acid 6.35

Tris 8.05

Boric acid 9.24

2. The initial pH of a buffer (50mL) is 6.0. After adding 5 mL of 1 M HCl, the pH of the buffer becomes 5.3. Calculate the buffer capacity of the buffer. Present your calculation steps clearly, show the formula and round your result to 2 decimal places, e.g. 2.235 becomes 2.24.

3. In this question, you are asked to provide a protocol on making a 100mL buffer, 0.2M, pH 4.2.

a) Please indicate only the most appropriate chemical/equipment that you will use for preparing the buffer. Choosing inappropriate items will result in mark deduction

Chemical / equipment

1. 0.2M Acetic acid, pKa 4.8
2. pH standards (pH 7, 4)
3. 0.1M Sodium acetate
4. P-1000 pipetman
5. 0.2M Citric acid, pKa 3.13
6. P-2 pipetman
7. 0.2M Sodium citric
8. Stir bar
9. 0.2M Trizma Base, pKa 8.08
10. Magnetic Stirrer plate
11. 0.2M Tris-Cl
12. Volumetric cylinders (100ml)
13. 0.4M HCl
14. Volumetric cylinders (1000ml)
15. NaOH
16. Beaker (100ml)
17. Blue color pipette tips
18. Beaker (200ml)
19. Yellow color pipette tips
20. pH meter

b) Show all related calculations on how the buffer can be prepared from the chemical ingredient(s) that you have chosen from part a).

c) Based on your answers from parts a) and b), work out a protocol for preparing the buffer. The protocol must be in point form and others can easily produce the buffer by following your instructions.