Question

Рассчитать рН в 0.01 М растворе NH4OH

Answer 1

Kb = 1,8 * 10^-5.
Концентрация гидроксид-анионов в 0,01М растворе составит
корень квадратный(1,8 * 10^-5 * 0,01) = 4,2 * 10^-4.
Определим рН раствора NH4OH:
pOH = -lg[OH^-] = - lg(4,2 * 10^-4) = 3,37; тогда рН = 14 - 3,37 = 10,63.
Ответ: 10,63.

Answer 2

Calculation of pH in a 0.01 M solution of NH4OH

To calculate the pH of a 0.01 M solution of NH4OH, we need to consider the dissociation of NH4OH in water. NH4OH is an example of a weak base, and it partially dissociates in water to form NH4+ and OH- ions.

The dissociation reaction of NH4OH can be represented as follows: NH4OH ⇌ NH4+ + OH-

To calculate the pH, we need to determine the concentration of OH- ions in the solution. Since NH4OH is a weak base, we can assume that the concentration of NH4+ ions is equal to the concentration of OH- ions.

Given that the concentration of NH4OH is 0.01 M, we can assume that the concentration of NH4+ and OH- ions is also 0.01 M.

Now, we can use the equation for the ion product of water (Kw) to calculate the concentration of H+ ions in the solution. The equation for Kw is as follows: Kw = [H+][OH-]

At 25°C, the value of Kw is approximately 1.0 x 10^-14.

Since the concentration of NH4+ and OH- ions is 0.01 M, we can assume that the concentration of H+ ions is also 0.01 M.

To calculate the pH, we can use the equation: pH = -log[H+]

Substituting the concentration of H+ ions into the equation, we get: pH = -log(0.01)

Calculating this value, we find that the pH of a 0.01 M solution of NH4OH is approximately 2.

Please note that this calculation assumes ideal conditions and does not take into account any other factors that may affect the pH of the solution.