Answer to Question #236363 in General Chemistry for Olala

Question

The Henderson Hasselback equation:

𝑝𝐻 = 𝑝𝐾𝑎 + log conj𝑢𝑔𝑎𝑡𝑒 𝑏𝑎𝑠𝑒 (𝐴) 𝑤𝑒𝑎𝑘 𝑎𝑐𝑖𝑑 (𝐻𝐴)

𝐵𝑢𝑓𝑓𝑒𝑟 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 = 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑂𝐻− 𝑜𝑟 𝐻3𝑂 + (𝑝𝐻 𝑐ℎ𝑎𝑛𝑔𝑒)(𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑏𝑢𝑓𝑓𝑒𝑟 𝑖𝑛 𝐿)

Procedure:

C. Bicarbonate Buffer

3. 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

DATA:

Show your calculation:

3. Preparation of Bicarbonate Buffer

Calculated Volume

CH3COOH

KH2PO4

Actual pH of the buffer:

Answer 1

The formula for the Henderson–Hasselbalch equation is: pH=pKa+log([A−][HA]) pH = p K a + log ( [ A − ] [ HA ] ) , where pH is the concentration of [H+], pKa is the acid dissociation constant, and [A–] and [HA] are concentrations of the conjugate base and starting acid.