Sonni added 23.79 mL of KOH to 20.00 mL of 0.393 M HF until the equivalence point was reached. What is the concentration of conjugate base at the equivalence point after the initial neutralization?

Respuesta :

Answer:

0.1795 M

Explanation:

From the given information:

The equation is:

[tex]\mathbf{HF_{(aq)}+ KOH_{(aq)} \to KF _{(aq)} + H_2O}[/tex]

From the above equation, the reaction will go to completion due to the strong base:

At the equivalence point, moles of acid (HF) will be equal to moles of base (KOH)

[tex]\text{Number of moles = Volume} \times Molarity[/tex]

Thus. since moles of HF = moles of KOH

Then; 0.020 × 0.393 M = 0.02379 × (x) M

(x) M = [tex]\dfrac{0.02 \times 0.393 \ M}{0.02379}[/tex]

(x) = 0.3304 M

Thus, the molarity of KOH = 0.3304 M

Using the balanced neutralization reaction;

moles of HF = moles of KOH = moles of conjugate base = 0.00786 mol

Volume = 0.020 L + 0.02379 L

Volume = 0.04379 L

Volume of the solution =  0.04379 L

Therefore; Molarity = [tex]\dfrac{moles}{volume}[/tex]

Molarity = [tex]\dfrac{0.00786 \ mol}{0.04379 \ L}[/tex]

Molarity = 0.17949 mol/L

= 0.1795 M

After the initial neutralization, the molarity at the equivalence point will be:

"0.17949 mol/L"

Concentration of solution

According to the question,

→ HF (aq) + KOH (aq) [tex]\rightarrow[/tex] KF (aq) + H₂O

Since, moles of HF = moles of KOH

We know that,

Number of moles = Volume × Molarity

→ 0.020 × 0.393 = 0.02379 × M

By applying cross-multiplication,

The molarity of KOH be:

M = [tex]\frac{0.02\times 0.393}{0.02379}[/tex]

   = [tex]\frac{0.00786}{0.02379}[/tex]

   = 0.3304 M

By using balanced neutralization reaction,

Volume = 0.020 + 0.02379

             = 0.04379 L

hence,

The molarity will be:

= [tex]\frac{Moles}{Volume}[/tex]

By substituting the values,

= [tex]\frac{0.00786}{0.04379}[/tex]

= 0.17949 mol/L

Thus the response above is correct.

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