Question

Provide explaination for the following:

a). Write the ionization equations for the protons of a triprotic acid.

b). Do you need to use an indicator when you are doing a pH titration?

c). What is the pH of 0.10 M HCl? 0.10 M CH3CO2H? 0.10 M H2SO4?

d). How many trials of each titration should you carry out in order to obtain dependable results?

Answer 1

a) Suppose the formula of triprotic acid is H₃A.

Ionization equations:

b) Indicator is used to locate th end point in treditional titration. But, no need to use an indicator in pH titration because sudden pH change indicate th end point.

c)

pH of 0.10 HCl:

HCl is strong acid. So, [H⁺] = concentration of HCl

pH of 0.10 M CH3CO2H:

CH3CO2H is a weak acid.

K_a for acetic acid is 1.75*10^-5

[H⁺] = 0.001323 M

pH of 0.10 M H₂SO₄:

H₂SO₄ is also strong acid. [H⁺] = 2*concentration of H₂SO₄ = 0.20 M

d) More than two trials.