Question

In: Chemistry

Consider the acid-base equation HF(aq) + CN‾(aq) → (equilibrates with) F‾(aq) + HCN(aq). The Ka of...

Consider the acid-base equation HF(aq) + CN‾(aq) → (equilibrates with) F‾(aq) + HCN(aq).

The Ka of HF is 7.1x10-4, while the Kb of CN‾ is 2.0x10-5.

(a) Label each reactant and product as stronger acid, stronger base, weaker acid, or weaker base

(b) Write out the Ka chemical equations for HF and for HCN.

(c) Calculate Kc for the reaction HF(aq) + CN‾(aq) → F‾(aq) + HCN(aq)

Solutions

Expert Solution

a) weaker acid is HF stromger acid is HCN.

weaker base is CN- stronger base is F-.

b) Ka chemical equation for HF is equal to HF(aq)-> H+(aq) + F-(aq) and Ka equals [H+][F-]/[HF]

Ka chemical equation for HCN is equal toHCN(aq)-> H+(aq) + CN-(aq) and Ka equals [H+][CN-]/[HCN]

c) Kc equals to 1/Ka X 1/Kb

1/7.1*10-4 X 1/2.0*10-5

1.4*103X 5*104

equals 7*107

Hence, Kc equals to 7*107


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