Multiple Choice
Identify a Bronsted-Lowry acid with weakest conjugate base.
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10. Acids and Bases
Ka and Kb
Multiple Choice
Hypobromous acid (Ka = 2.8 × 10−9) and hydrocyanic acid (Ka = 4.9 × 10−10) are both weak acids. Determine if reactants or products are favored in the following reaction.
HBrO (aq) + CN− (aq) ⇌ BrO− (aq) + HCN (aq)
A
Reactants
B
Products
C
Both directions are favored equally
D
Neither direction is favored
Verified step by step guidance1
Identify the relationship between the base dissociation constant (Kb) and the acid dissociation constant (Ka) for a conjugate acid-base pair. This relationship is given by the equation: \( K_w = K_a \times K_b \), where \( K_w \) is the ion-product constant of water, typically \( 1.0 \times 10^{-14} \) at 25°C.
Rearrange the equation to solve for the acid dissociation constant \( K_a \): \( K_a = \frac{K_w}{K_b} \).
Substitute the given values into the equation: \( K_a = \frac{1.0 \times 10^{-14}}{1.76 \times 10^{-5}} \).
Perform the division to calculate \( K_a \). This will give you the acid dissociation constant of the conjugate acid of NH3.
Compare the calculated \( K_a \) value with the provided options to determine the correct answer.
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