Question

A hydrochloric (HCI) solution has a molar concentration of 0.0045 M, calculate the [H3O+], [OH-] and pH of the solution. Remember that Kw=

1.0x10-14M2

Answer 1

1) H30+ or H+ concentration is 0.0045M.

2) OH- concentration is 2.2 * 10^-12 M

3) pH = 2.35

Step-by-step explanation:

1) HCl is strong acid so it completely dissociates which means you have

HCl------> H+ + Cl-

0-------> 0.0045 M, 0.0045M

We know now that H30+ or H+ concentration is 0.0045M.

2) H3O+ and OH- are related via the auto ionization of water.

Kw = 1.0*10^-14

(H3O) * (OH-) = 1.0*10^-14

OH- = ( 1.0*10^-14) / (0.0045) = 2.2 * 10^-12 M

3) pH measures the acidity based on the amount of hydrogen/hydronium ions in solution. H+ and H3O+ are both the same thing (either way it permissible to write)

The formula is pH= - log (H+) [now we just plug in the H+ we found)

pH = - log [0.0045] = 2.35