What volume (mL)of potassium hydroxide will it take to reach the equivalence point in a 16.3 mL aliquot of triprotic acid?
A)2.22
B)18.3
C)55.0
D)6.11
E)120

Question

What volume (mL)of  potassium hydroxide will it take to reach the equivalence point in a 16.3 mL aliquot of  triprotic acid?
A)2.22 
B)18.3 
C)55.0 
D)6.11 
E)120

Quizplus · Accepted Answer

This is a stoichiometry problem involving acid-base titration. We need to determine the volume of KOH needed to reach the equivalence point with 16.3 mL of triprotic acid.

First, we need to determine the moles of acid present in the 16.3 mL aliquot. We know that the triprotic acid has three ionizable hydrogen atoms, so it can potentially donate three moles of H+ ions. Therefore, its molarity will be three times that of the H+ ion concentration, which is 0.050 M (from the first dissociation):

Molarity of triprotic acid = 3 x 0.050 M = 0.150 M

Next, we need to use the balanced chemical equation for the reaction of KOH with the triprotic acid to determine the mole ratio between them. The balanced equation is:

H3A + 3 KOH → K3A + 3 H2O

For every one mole of triprotic acid, we need three moles of KOH to reach the equivalence point.

Finally, we can use the equation:

moles of KOH = moles of acid

to determine the volume of KOH needed:

moles of KOH = 0.150 M x 0.0163 L = 0.002445 mol

Since we need three times as many moles of KOH, we can multiply by 3 to get the total moles needed for the equivalence point:

moles of KOH needed = 0.002445 mol x 3 = 0.007335 mol

Now we can use the molarity of the KOH solution to convert moles to volume:

0.007335 mol / 0.1337 M = 0.055 L = 55.0 mL

Therefore, the answer is C) 55.0 mL.

What Volume (ML)of Potassium Hydroxide Will It Take to Reach