Answer to Question #244502 in General Chemistry for Mr. Yoso

Question

Prepare 100 mL of 0.200 bicarbonate buffer, pH 10 by calculating the mass of sodium bicarbonate and sodium carbonate.

    a. Use the Henderson-Hasselbalch equation to calculate the volume of each stock

        solution needed.  pH = pKa + log [conjugate base] / [weak acid]1

    b. Check your calculations with other students. See the instructor if there is uncertainty.

    c. Make the solution and check the pH of a portion of your buffer solution using the pH meter.

                                              L = 245μL 

Answer 1

100 ml × 0.2 = 20 ml

Molar mass of sodium carbonate = 105.9888 g/mol

Molar mass of sodium bicarbonate = 84.007 g/mol

= 105.9888 × 84.007/20

= 4.452 × 102

= log 4.452 × 102 = 2.65

pH = 10 + 2.65 = 12.65