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# Dissociation of HF in Water and Reaction with Strong Base

1. HF(aq) + H2O(l) <----> H3O+(aq) + F- (aq)
Hydrofluoric acid dissociates in water as represented by the above equation With Ka = 7.2 * 10^-4
A) write the equilibrium- constant expression for the dissociation of HF(aq) in water
B) calculate the molar concentration of H3O+ in a 0.4M HF solution

HF reacts with NaOHaq according to the reaction represented below
HF (aq) + OH-(aq) --> H2O(l) + F-(aq)

A volume of 15ml of 0.4 M NaOH is added to 25ml of 0.4M HF aq solution. Assume that the volumes are additive
C) calculate the number of moles of HF(aq) remaining in the solution
D) calculate the molar concentration of F-(aq) in the solution
E) calculate the pH of the solution

#### Solution Preview

Please see the attached file for detailed solution.

equilibrium
1. HF(aq) + H2O(l) = H3O+(aq) + F-

Hydrofluoric acid dissociates in water as represented by the above equation
With Ka = 7.2 * 10^-4

A) write the equilibrium- constant expression for the dissociation of HF(aq) in water

B) calculate the molar concentration of H3O+ in a 0.4M HF solution
HF(aq) + H2O(l) = H3O+(aq) + F-
Initial 0.4
Equilibrium: 0.4 -x x x
So substituting to the equation is (A)

Since ...

#### Solution Summary

The first part solution shows the calculation of H+ ion concentration of weak acid HF using its dissociation constant Ka. The second part solution shows step-by-step explanations of the titration of HF with strong base NaOH.

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