Question

Consider the titration of a 27.0 ml sample of 0.170 moll-1 ch3cooh (ka=1.8×10-5) with 0.145 moll-1 naoh. Determine the initial pH.

Answer 1

The initial pH before any amount of the NaOH solution has been added can be calculated using the Henderson-Hasselbalch equation. The equation is given by pH = pKa + log([A-]/[HA]). Since acetic acid (CH3COOH) is a weak acid, we can assume that the concentration of CH3COOH remains constant during the titration. Therefore, the initial pH can be calculated using the equation pH = -log(Ka) = -log(1.8 × 10^-5) = 4.74.

Step-by-step explanation:

The initial pH before any amount of the NaOH solution has been added can be calculated using the Henderson-Hasselbalch equation. The equation is given by pH = pKa + log([A-]/[HA]). Since acetic acid (CH3COOH) is a weak acid, we can assume that the concentration of CH3COOH remains constant during the titration. Therefore, the initial pH can be calculated using the equation pH = -log(Ka) = -log(1.8 × 10^-5) = 4.74.