To determine the concentration of 10.31mL of an unknown solution of a monoprotic acid, it is titrated with 0.172M sodium hydroxide. The initial reading on the buret of sodium hydroxide is 2.19mL. The final reading is 13.41mL. What is the concentration of the unknown acid?
The monoprotic acid is HA.
HA + NaOH ==> NaA + H2O
mols NaOH = M x L = ?
(note: volume NaOH = 13.41-2.19 = ? mL and convert to L).
Then mols HA = mols NaOH
M HA = mols HA/L HA.
To determine the concentration of the unknown acid solution, you can use the concept of stoichiometry and the balanced chemical equation for the reaction between the acid and sodium hydroxide.
The balanced chemical equation for the reaction between a monoprotic acid and sodium hydroxide can be written as follows:
Acid + Sodium Hydroxide → Salt + Water
Since it is mentioned that the acid is monoprotic, it means that for every acid molecule, it can donate only one proton (H+ ion) during the reaction.
Now, let's analyze the information given in the question:
Volume of sodium hydroxide used = Final volume - Initial volume
V(NaOH) = 13.41 mL - 2.19 mL = 11.22 mL = 0.01122 L
Concentration of sodium hydroxide (NaOH) = 0.172 M
From the balanced chemical equation, we can see that the ratio between the moles of the acid and the moles of sodium hydroxide is 1:1. This means that 1 mole of acid reacts with 1 mole of sodium hydroxide.
Using this information, we can set up a proportion to calculate the concentration of the unknown acid:
(Moles of NaOH) / (Volume of NaOH) = (Moles of Acid) / (Volume of Acid)
To find the moles of sodium hydroxide, we can use the formula:
Moles = Concentration (M) × Volume (L)
M(NaOH) = 0.172 M × 0.01122 L = 0.00193 moles
Since the ratio of moles between the acid and sodium hydroxide is 1:1, the concentration of the unknown acid will also be 0.00193 moles/L or 0.00193 M.
Therefore, the concentration of the unknown acid is 0.00193 M.