Question

Calculate the pH of each of the following solutions:

Part A

A sample of seawater that has an OH− concentration of 1.68×10⁻⁶ M .

Part B

A sample of acid rain that has an H3O+ concentration of 4.5×10⁻⁵ M .

Answer 1

Solution:

• Part - A:

​Given:     [OH^- ] = 1.68 x 10 ^{- 6} M

Step - 1:

We know, pOH = - log [OH ^-] = - log (1.68 x 10 ^--6) = 5.77

pOH = 5.77

Step - 2:

We know also, pH + pOH = 14

Therefore.........   pH = 14 - pOH = 14 - 5.77 = 8.23

Answer to Part - A: ............pH = 8.23 ...... (Answer)

• Part - B:

​Given: [ H₃O⁺ ] = 4.5 x 10^-5 M

Step - 1:

We know, pH = - log [ H₃O⁺ ] = - log (4.5 x 10^-5) = 4.346 4.35

pH = 4.35

Therefore........Answer ..would be the following.. (i.e. to Part - B )

Answer to Part - B: ............pH = 4.35 ...... (Answer)