Question

chemist is using a solution of HNO3 that has a pH of 3.75. What is [OH− ] for the solution? × 10es001-1.jpg M n = What is the pOH of the solution?

Answer 1

5.62×10⁻¹¹ M

Step-by-step explanation:

Given the pH of the nitric acid, (
`HNO_3`)

pH = 3.75

Also, pH + pOH = 14

So, pOH = 14 - 3.75 = 10.25

pOH is the negative logarithm of the hydroxide ion concentration.

Thus,

pOH = -log[OH⁻ ]

So,

10.25 = -log[OH⁻ ]

[OH⁻ ] = Antilog (-10.25) = 5.62×10⁻¹¹ M

Answer 2

Step-by-step explanation:

Given parameters:

pH of HNO₃ = 3.75

Unknown:

[OH⁻], concentration of hydroxyl ions = ?

pOH of the solution = ?

Solution

The pH or pOH scale is a convenient way of expressing the level of acidity or alkalinity of aqueous solutions.

The pH of a solution is the negative logarithm to base 10 of the hydrogen ion concentration of the solution:

pH = -log₁₀[H⁺]

pOH = -log₁₀[OH⁻]

For any aqueous solution, the sum of the pH and pOH is 14. That is;

pH + pOH = 14

Now solving for [OH⁻]:

HNO₃ + H₂O → H₃O⁺ + NO₃⁻

Since pH + pOH = 14

pOH = 14 - pH = 14 -3.75 = 10.25

since pOH = -log₁₀[OH⁻]

10.25 = -log₁₀(OH⁻)

[OH⁻] = inverse log₁₀(-pOH)

[OH⁻] = inverse log₁₀(-10.25) = 5.62 x 10⁻¹¹moldm⁻³