Question

What is the pH of the solution formed after 20.0 mL of 0.20 M ketamine, C13H16ClNO, is titrated with 5.0 mL of 1.0 M HI? Kb = 3.0 ×10–7 for C13H16ClNO

A. 4.60

B. 7.00

✓C. 1.40

D. 2.20

Answer 1

we have:

Molarity of HI = 1 M

Volume of HI = 5 mL

Molarity of C13H16ClNO = 0.2 M

Volume of C13H16ClNO = 20 mL

mol of HI = Molarity of HI * Volume of HI

mol of HI = 1 M * 5 mL = 5 mmol

mol of C13H16ClNO = Molarity of C13H16ClNO * Volume of C13H16ClNO

mol of C13H16ClNO = 0.2 M * 20 mL = 4 mmol

We have:

mol of HI = 5 mmol

mol of C13H16ClNO = 4 mmol

4 mmol of both will react

excess HI remaining = 1 mmol

Volume of Solution = 5 + 20 = 25 mL

[H+] = 1 mmol/25 mL = 0.04 M

we have below equation to be used:

pH = -log [H+]

= -log (4*10^-2)

= 1.40

Answer: 1.40