Respuesta :
Answer:
The correct option is;
a. 11.21
Explanation:
The chemical equation for the reaction is;
NH₄OH ↔ NH₄⁺ + OH⁻
At the start of the reaction, we have;
NH₄OH ↔ NH₄⁺ + OH⁻
I [tex]{}[/tex] 0.15 0 0
C 0.15 - x +x +x
The [tex]k_b[/tex] = 1.78 × 10⁻⁵
Therefore, we have;
1.78 × 10⁻⁵ = [NH₄⁺][OH⁻]/NH₄OH = x²/(0.15 - x)
Which gives;
(0.15 - x) 1.78 × 10⁻⁵ = x²
x² + 1.78 × 10⁻⁵x - 2.67× 10⁻⁶ = 0
Factorizing the above equation online, gives;
(x + 0.00164294)(x - 0.00162514) = 0
Therefore;
x = -0.00164294, or x = 0.00162514
We use the positive result, which is x = 0.00162514 = 1.62514 × 10⁻³ = [OH⁻]
Therefore;
pOH = -log[OH⁻] = -log(0.00162514) = 2.789
pH + pOH = 14
Therefore;
pH = 14 - pOH = 14 - 2.789 ≈ 11.21089
The pH of a 0.15 M NH₄OH solution with [tex]k_b[/tex] = 1.78 × 10⁻⁵ = 11.21.
The pH of a 0.15 M NH₄OH solution with [tex]k_b[/tex] = 1.78 × 10⁻⁵ is approximately 11.21
pH value is the measure of acidic or base properties of a solution.
The answer to the given question is a. 11.21. It is explained as follows.
The range of pH value is between 0 to 14 in which value 7 is the neutral pH which is associate with water.
The water has no dominant properties of acid neither base.
The pH value below 7 is for acidic properties and for above 7 is associate with base properties.
The pH value of 0.15 M NH4OH solution is 11.21 as it displays strong base properties.
The correct answer is a. 11.21.
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