Pineapple juice contains 3.16 x 10-5 M [H3O+]. What is the pH of pineapple juice?

Question

Pineapple juice contains 3.16 x 10^-5 M [H₃O⁺]. What is the [OH^-] of pineapple juice and is it acidic or basic?

Calculate the [H₃O⁺] of a solution that contains 8.4 x 10^-2 M [OH^-] and is the solution acidic or basic:

The pH of black tea is 6.37. What is the [H₃O⁺] and is this acidic or basic?

 

Green tea has a pH around 8.2, what is the [OH^-] and is this acidic or basic?

 

The pH of Cherry Coke is 2.52, what is the [H₃O⁺] and is this acidic or basic?

 

Calculate the [H₃O⁺] of a solution that contains 9.8 x 10^-11 M [OH^-] and is the solution acidic or basic:

Answer 1

1.

pH = - log( 3.16 x 10^-5 ) = 4.50

pH + pOH = 14 -> pOH = 14 - 4.50 = 9.5

9.50 = - log [OH^-] -> log [OH^-] = - 9.50 -> [OH^-] = 10^-9.50 = 3.16 x 10^-10 M

Since pH = 4.50, the pineapple juice is acidic.

2.

K_w = [H₃O⁺][OH^-] = 1.0 x 10^-14 , where K_w is the auto-ionization constant for water

[H₃O⁺] = 1.0 x 10^-14 / 8.4 x 10^-2 = 1.19 x 10^-13 M

[OH^-] > [H₃O⁺] -> the solution is basic

3.

[H₃O⁺] = 10 ^-6.37 = 4.27 x 10^-7 M

pH of black tea is 6.37 -> acidic

4.

pOH = 14 - 8.2 = 5.8

[OH^-] = 10^-5.8 = 1.58 x 10^-6 M

pH = 8.2 -> basic

5.

[H₃O⁺] = 10^-2.52 = 3.02 x 10^-3 M

pH = 2.52 -> acidic



6.

[H₃O⁺] = 1.0 x 10^-14 / 9.8 x 10^-11 = 1.02 x 10^-4 M

[H₃O⁺] > [OH^-] , the solution is acidic.