i am confuse to prepare the buffer please tell me how to prepare the 0.02 M Sodium phosphate buffer, pH 6.9 with 0.006 M sodium chloride
To prepare a sodium phosphate buffer with a pH of 6.9 and a concentration of 0.02 M, along with 0.006 M sodium chloride, you will need a few reagents and equipment. Here is a step-by-step guide on how to prepare the buffer:
1. Calculate the amount of each reagent needed:
- Sodium phosphate dibasic (Na2HPO4): You will need to know the molar mass of Na2HPO4. Let's assume it's 142.0 g/mol. To prepare a 0.02 M solution, you need to multiply the molar mass by the desired concentration (0.02 M) and the final volume you want to prepare (let's say 1 L).
Mass of Na2HPO4 = (0.02 mol/L) x (142.0 g/mol) x (1 L) = 2.84 g
- Sodium phosphate monobasic (NaH2PO4): You will need to know the molar mass of NaH2PO4. Let's assume it's 120.0 g/mol. To prepare a 0.02 M solution, you need to multiply the molar mass by the desired concentration (0.02 M) and the final volume you want to prepare (let's assume 1 L).
Mass of NaH2PO4 = (0.02 mol/L) x (120.0 g/mol) x (1 L) = 2.4 g
- Sodium chloride (NaCl): To prepare a 0.006 M solution, you need to multiply the molar mass of NaCl (58.44 g/mol) by the desired concentration (0.006 M) and the final volume you want to prepare (let's say 1 L).
Mass of NaCl = (0.006 mol/L) x (58.44 g/mol) x (1 L) = 0.35 g
2. Weigh the required amounts of sodium phosphate dibasic (Na2HPO4), sodium phosphate monobasic (NaH2PO4), and sodium chloride (NaCl) separately using a balance.
3. Dissolve Na2HPO4 in a container using some distilled water. Stir the solution gently until all the Na2HPO4 is dissolved.
4. Once Na2HPO4 is fully dissolved, add NaH2PO4 and stir the solution thoroughly.
5. Add NaCl to the solution and continue stirring until all components are completely dissolved.
6. Adjust the pH of the solution to 6.9 using a pH meter or pH indicator strips. To increase the pH, you can add small amounts of a strong base, such as sodium hydroxide (NaOH). To decrease the pH, you can add small amounts of a strong acid, such as hydrochloric acid (HCl). Remember to adjust the pH gradually and monitor the changes to reach the desired pH.
7. Once the desired pH is achieved, add distilled water to the solution to make a total volume of 1 L, or the desired final volume you have chosen.
8. Stir the solution gently to ensure uniform mixing.
Congratulations! You have successfully prepared a 0.02 M sodium phosphate buffer with a pH of 6.9 and 0.006 M sodium chloride.