Question

Given [OH-] = 5.5 x 10-10M Find: [H3O+] and pH Is this acidic, basic or neutral?

Answer 1

Step-by-step explanation:

Given parameters:

Hydroxide ion concentration = 5.5 x 10⁻¹⁰M

Unknown:

concentration of hydroxonium ion [H₃O⁺]= ?

pH = ?

Solution

To determine the concentration of the hydroxonium ion, we know that from the ionic product of water:

[H₃O⁺][OH⁻]= 10⁻¹⁴

[H₃O⁺] =
`(10^(-14) )/(OH^(-) )`

[H₃O⁺] =
`(10^(-14) )/(5.5 x 10^(-10) )`

[H₃O⁺] = 1.8 x 10⁻⁵M

To find the pH of the solution, we use the expression below:

pH = -log₁₀[H₃O⁺]

pH = -log₁₀ 1.8 x 10⁻⁵ = -(-4.74) = 4.7

Since the pH of the solution is 4.7, it is acidic.