1. How do you prepare a 100mL of 0.1 M phosphate buffer?
To make 100 mL of 0.1 M phosphate buffer:
Calculate the amount of sodium phosphate needed. moles of sodium phosphate = (0.1 mol/L) x (0.1 L) = 0.01 moles mass of sodium phosphate = moles x molar mass = 0.01 moles x 142 g/mol = 1.42 g
Dissolve 1.42 g of sodium phosphate in distilled water in a 100 mL volumetric flask.
Adjust the pH of the solution to the desired value (usually around 7.4) using a strong acid or strong base.
Bring the solution to the final volume (100 mL) with distilled water.
2. From the anterior buffer, how do you make 100mL of 0.05 M?
To make 100 mL of 0.05 M phosphate buffer from the 0.1 M stock solution:
Calculate the amount of the 0.1 M phosphate buffer needed. moles of phosphate buffer = (0.05 mol/L) x (0.1 L) = 0.005 moles
Calculate the volume of the 0.1 M phosphate buffer needed. moles = concentration x volume (in liters) volume = moles / concentration = 0.005 moles / 0.1 mol/L = 0.05 L or 50 mL
Measure 50 mL of the 0.1 M phosphate buffer using a graduated cylinder or pipette.
Dilute the 50 mL of 0.1 M phosphate buffer with 50 mL of distilled water in a 100 mL volumetric flask.
Adjust the pH of the solution to the desired value (usually around 7.4) using a strong acid or strong base.
Bring the solution to the final volume (100 mL) with distilled water.
3. Calculate the amount of ammonium sulfate necessary to get a 20% solution?
PLEASE ANSWER QUESTION #3, QUESTIONS #1 AND #2 ARE ONLY FOR GUIDANCE
THIS IS PART OF AN LDH PURIFICATION EXPERIMENT.
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