how to prepare 1M,50ml buffer solution by taking Na2HPO4 and NaH2PO4.
In biochemistry the molarity of the buffer is the sum of both the acid and the conjugate base. Your post just gives the total but not the breakdown; therefore, I would suggest 50 mL(0.05L) for 0.5M each. That is 0.5 x 0.05 = 0.025 moles.
g each = moles x molar mass.
To prepare a 1M, 50ml buffer solution using Na2HPO4 (disodium hydrogen phosphate) and NaH2PO4 (sodium dihydrogen phosphate), you need to follow these steps:
1. Determine the desired volume of the buffer solution: In this case, it is 50ml.
2. Calculate the amounts of Na2HPO4 and NaH2PO4 needed based on their molar masses:
- Molar mass of Na2HPO4 = 141.96 g/mol
- Molar mass of NaH2PO4 = 119.98 g/mol
3. Calculate the moles of Na2HPO4 required for a 1M solution:
- Moles = Molarity × Volume (in liters)
- Moles = 1M × 0.05L (50ml converted to liters)
- Moles = 0.05 mol
4. Calculate the moles of NaH2PO4 required based on their molar ratio with Na2HPO4:
- The balanced equation for their reaction is:
Na2HPO4 + NaH2PO4 ↔ Na3PO4 + H2O
- The reaction shows a 1:1 molar ratio between Na2HPO4 and NaH2PO4. So, the moles of NaH2PO4 required are also 0.05 mol.
5. Convert the moles of Na2HPO4 and NaH2PO4 to grams:
- Mass (g) = Moles × Molar mass
- Mass of Na2HPO4 = 0.05 mol × 141.96 g/mol ≈ 7.1 g
- Mass of NaH2PO4 = 0.05 mol × 119.98 g/mol ≈ 6 g
6. Dissolve the calculated amounts of Na2HPO4 and NaH2PO4 in distilled water:
- Take a container and add some distilled water (approximately half the final volume of the buffer solution).
- First, add Na2HPO4 to the container and stir until it is completely dissolved.
- Next, add NaH2PO4 to the container and again stir until fully dissolved.
7. Once both salts are completely dissolved, add distilled water to bring the total volume of the solution to 50ml.
8. The resulting solution is a 1M, 50ml buffer solution made from Na2HPO4 and NaH2PO4.
Note: The pH of the buffer solution will depend on the pKa values of Na2HPO4 and NaH2PO4 and the ratio of their amounts used in the solution.