How would you prepare 500 ml of a 1.8 M phosphate buffer (pH 6.8) containing 4.5 x 10-6 M CaCl2 and 52 mM sucrose?
pH = pK + log(base)/(acid)
6.8 = pK2 + log(base)/(acid)
Substitute pK2 and solve for b/a ratio.
That's two unknowns. The second equation is
base + acid = 1.8M
Solve the two equations simultaneously for acid and base. Along the route, and before you make it up to the final volume, add enough solid CaCl2 to make3 1.8M and enough sucrose to make it 52 mM.
To prepare 500 ml of a 1.8 M phosphate buffer (pH 6.8) containing 4.5 x 10-6 M CaCl2 and 52 mM sucrose, you will need the following steps:
Step 1: Calculate the amount of phosphate needed
- Determine the molar mass of the phosphate (PO4) molecule, which consists of one phosphorus atom (P) and four oxygen atoms (O).
- Calculate the amount of phosphate needed using the formula: mass = moles x molar mass.
- In this case, you want to prepare a 1.8 M solution, which means you need 1.8 moles of phosphate per liter (1000 ml) of solution.
- Multiply the moles by the molar mass to find the mass of phosphate needed.
Step 2: Prepare the phosphate buffer solution
- Dissolve the calculated amount of phosphate in a small volume (e.g., 100 ml) of distilled water.
- Adjust the pH of the phosphate solution to 6.8 using appropriate pH-adjusting agents, such as sodium hydroxide (NaOH) or hydrochloric acid (HCl).
- Once the pH is adjusted, make up the final volume to 500 ml with distilled water.
Step 3: Prepare the CaCl2 solution
- Calculate the amount of CaCl2 needed to prepare a solution of 4.5 x 10-6 M in a final volume of 500 ml.
- Determine the molar mass of CaCl2, which consists of one calcium atom (Ca) and two chlorine atoms (Cl).
- Calculate the amount of CaCl2 using the formula: mass = moles x molar mass.
- Dissolve the calculated mass of CaCl2 in a small volume (e.g., 100 ml) of distilled water.
- Make up the final volume of the CaCl2 solution to 500 ml with distilled water.
Step 4: Prepare the sucrose solution
- Calculate the amount of sucrose needed to prepare a solution of 52 mM in a final volume of 500 ml.
- Determine the molar mass of sucrose, which consists of carbon, hydrogen, and oxygen atoms.
- Calculate the amount of sucrose using the formula: mass = moles x molar mass.
- Dissolve the calculated mass of sucrose in a small volume (e.g., 100 ml) of distilled water.
- Make up the final volume of the sucrose solution to 500 ml with distilled water.
Step 5: Combine the solutions
- Mix the prepared phosphate buffer, CaCl2 solution, and sucrose solution together.
- Ensure that the solutions are thoroughly mixed to obtain a homogeneous mixture.
- You now have a 500 ml solution of a 1.8 M phosphate buffer (pH 6.8) containing 4.5 x 10-6 M CaCl2 and 52 mM sucrose.
Note: It is important to take proper safety precautions while handling chemicals and to use accurate measuring equipment, such as a balance or graduated cylinders, for precise measurements.