Question

For the following H30 concentration list the pH and the OH concentration in

Molarity) (5 points each, 10 points total)
[H30*]= 1.4*105 M
pH=
[OH]=

Answer 1

[H₃O]=1.4 x 10⁻⁵

pH = 5 - log 1.4

pOH = 9 + log 1.4

[OH⁻] = 1 x 10⁻¹⁴ : 1.4 x 10⁻⁵ = 7.14 x 10⁻¹⁰

Answer 2

[H3O+] = 1.4*10^-5 M

pH = 4.85

[OH-] = 7.08*10^-10

Step-by-step explanation:

As pH is a measure of hydronium H3O concentration, simply substitute [H3O+] into the following equation:
pH = -log[H+]
pH = -log(1.4*10^-5)
pH = 4.853871...
Round to 2-3 sig figs due to only being given data with 2 significant figures
pH = 4.85

One method to get to [OH-] is to turn pH into pOH and then use inverse functions to get [OH-]
pH + pOH = 14
4.85 + pOH = 14
pOH = 9.15

Then to get [OH-] from pOH:
pOH = -log[OH-]
9.15 = -log[OH-]
-9.15 = log[OH-]
10^(-9.15) = [OH-]
7.07945784 * 10^-10 = [OH]
Round based on given significant figures again:
7.08*10^-10 = [OH-]

(Feel free to add any questions & I'll be sure to reply if clarification is needed)