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To a 25.00 mL volumetric flask, a lab technician adds a 0.250 g sample of a weak monoprotic acid, HA , and dilutes to the mark with distilled water. The technician then titrates this weak acid solution with 0.0846 M KOH . She reaches the endpoint after adding 46.83 mL of the KOH solution. Determine the number of moles of the weak acid in the solution.

Respuesta :

Answer: The number of moles of the weak acid in the solution is 0.00396

Explanation:

To calculate the number of moles for given molarity, we use the equation:

[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex]      

a) [tex]{\text{Moles of}KOH=0.0846M\times 0.04683L=0.00396mol[/tex]

The balanced chemical reaction is:

[tex]HA+KOH\rightarrow KA+H_2O[/tex]  

1 mole of base uses = 1 mole of [tex]HA[/tex]  

0.00396  moles of base use = [tex]\frac{1}{1}\times 0.00396=0.00396[/tex] moles of [tex]HA[/tex]  

Thus the number of moles of the weak acid in the solution is 0.00396

Eduard22sly

The number of mole of the weak acid in the solution is 0.00396 mole

We'll begin by calculating the number of mole of KOH in the solution. This can be obtained as follow:

Molarity of KOH = 0.0846 M

Volume = 46.83 mL = 46.83 / 1000 = 0.04683 L

Mole of KOH =.?

Mole = Molarity x Volume

Mole of KOH = 0.0846 × 0.04683

Mole of KOH = 0.00396 mole

  • Finally, we shall determine the number of mole of weak acid, HA in the solution. This can be obtained as follow:

HA + KOH —> KA + H₂O

From the balanced equation above,

1 mole of HA reacted with 1 mole of KOH

Therefore,

0.00396 mole of HA will also react with 0.00396 mole of KOH.

Thus, the number of mole of the weak acid in the solution is 0.00396 mole

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