객관식
The Ka value for a weak acid is _________ than the Ka value for a strong acid because the weak acid ionizes to a _________ extent than the strong acid.
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17. Acid and Base Equilibrium
Ka and Kb
객관식
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
검증된 단계별 안내1
Identify the acids and their conjugate bases in the reaction: HBrO is the acid on the left side, and HCN is the acid on the right side. CN⁻ and BrO⁻ are their respective conjugate bases.
Write the equilibrium expression for the acid-base reaction, which involves the transfer of a proton from HBrO to CN⁻, forming BrO⁻ and HCN.
Compare the acid strengths by looking at their acid dissociation constants (K_a): HBrO has K_a = 2.8 × 10^{-9} and HCN has K_a = 4.9 × 10^{-10}. The acid with the larger K_a is stronger.
Since HBrO is the stronger acid (larger K_a), the equilibrium will favor the formation of the weaker acid and its conjugate base, meaning the products (BrO⁻ and HCN) are favored.
Conclude that the equilibrium lies toward the products side because the reaction proceeds from the stronger acid and base to the weaker acid and base.
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