Respuesta :
Answer: 81.8 g/mol
Explanation:
We’re being asked to calculate the molar mass of an unknown acid based on our interpretation of the titration curve.
Recall that at the equivalence point of a titration:
[tex]moles\ acid=moles\ base[/tex]
We can use this equation to calculate the moles of the unknown acid. Since the unknown acid only has a single Ka value, it is a monoprotic acid, which means there will be one equivalence point for the titration.
Mole-to-mole comparison: A mole-to-mole comparison will then show that 1 mole of the unknown acid reacts with 1 mole of Na(OH).
Molarity of NaOH: The molarity of NaOH (the base) is given as 0.112 M or 0.112 mol/L NaOH.
As for the volume of NaOH (the base) added, we can interpret this from the graph:
we can see that at the equivalence point, 25 mL of the vase was added.
Vbase is more or less 25.00 mL
Recall:
1 mL = 10-3 L
Solving for MMacid:
Again, at the equivalence point of a titration:
[tex]moles\ acid=moles\ base=0.112*25*10^{-3}[/tex]
[tex]moles\ acid = 0.0028\ moles[/tex]
Molar mass is defined as the mass in grams of one mole of a substance.
The units of molar mass are grams per mole, abbreviated as g/mol and uses the formula below:
[tex]molar\ mass=\frac{mass\ of\ compound\ in\ grams}{mole\ of\ compound\ in\ moles}[/tex]
[tex]=\frac{mass\ of\ acid}{moles\ acid}[/tex]
[tex]=\frac{0.229g}{0.0028mol}[/tex]
molar mass acid = 81.8 g/mol
The molar mass of the unknown acid is 81.8 g/mol.
An acid that donates a single hydrogen atom or proton is called monoprotic acid. The molar mass of the unknown acid in titration is 81.8 gm/mol.
What is molar mass?
The molar mass of any substance is the ratio of the mass of the substance in grams and moles of the same substance in mol. The molar mass is given by g/mol.
In titration, the moles of acid are equivalent to acid and can be used to determine the moles of the unknown acid from the base.
We know, that the molarity of base (NaOH) is 0.112 M, and the graph is used to know the volume to be 25 ml.
The moles of the base is calculated as:
[tex]\begin{aligned} \rm moles &=\rm molarity \times volume\\\\&= 0.112 \;\rm M \times 25 \times 10^{-3}\;\rm L\\\\&= 0.0028\;\rm moles\end{aligned}[/tex]
Hence, moles of acid is 0.0028 mol.
The molar mass of acid is calculated as:
[tex]\begin{aligned}\rm Molar \;mass &= \rm \dfrac{mass}{moles}\\\\&= \dfrac{0.229}{0.0028}\\\\&= 81.8\;\rm g/mol\end{aligned}[/tex]
Therefore, 81.8 g/mol is the molar mass of unknown monoprotic acid.
Learn more about molar mass here:
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