Question

Prepare 250.00 mL of an phosphate buffer (pK_a=7.199) with a total phosphate concentration of 0.020000 M and a pH of 6.900 using the usual method for preparing a buffer using a pH meter, Dibasic Sodium Phosphate and a HCl solution.

1. Calculate the amount of Dibasic Sodium Phosphate (Na₂HPO₄ FW=141.959) required to prepare this solution. Report your answer in the appropriate units and to the appropriate number of significant figures to match the instrument you plan to use to measure the Dibasic Sodium Phosphate :

2. Prepare 1 Liter of an approximately 0.025 M NaOH solution using a 10 M NaOH stock solution.

Calculate the amount of the 10 M NaOH required to prepare this solution. Since we will be standardizing the solution, we can use a graduated cylinder to make the measurement. REPORT YOUR ANSWER WITH THREE (3) SIGINIFCANT FIGURES

3. For the above NaOH solution, assuming the volumes are additive, how much DI Water should be placed into your plastic bottle before adding the 10M NaOH? Since we will be standardizing the solution, we can use a graduated cylinder to make the measurement. REPORT YOUR ANSWER WITH THREE (3) SIGINIFCANT FIGURES

Answer 1

btapkat log Ewale] Carid] 6.92 3.190t dog reall] Cheed7 log Tuale) - 0.999 Taid 20.502 - (Acid] = {walt 20.04 m 0.502 1000 mt contains 20.04 moles 250 mL > 0.04250 29.953x10-3 1000 moles 21.413g