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

Answer:

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

Answer 2

Answer:

5.62×10⁻¹¹ M

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