Respuesta :
Answer: The identity of the unknown acid is butanoic acid or ascorbic acid.
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}\times 1000}{\text{Volume of solution (in L)}}[/tex]
Molarity of NaOH solution = 0.570 M
Volume of solution = 39.55 mL
Putting values in above equation, we get:
[tex]0.570M=\frac{\text{Moles of NaOH}\times 1000}{39.55}\\\\\text{Moles of NaOH}=\frac{0.570\times 39.55}{1000}=0.0225mol[/tex]
The chemical equation for the reaction of NaOH and monoprotic acid follows:
[tex]NaOH+HX\rightarrow NaX+H_2O[/tex]
By Stoichiometry of the reaction:
1 mole of NaOH reacts with 1 mole of HX
So, moles of monoprotic acid = 0.0225 moles
The chemical equation for the reaction of NaOH and diprotic acid follows:
[tex]2NaOH+H_2X\rightarrow 2NaX+2H_2O[/tex]
By Stoichiometry of the reaction:
2 moles of NaOH reacts with 1 mole of diprotic acid
So, moles of diprotic acid = [tex]\frac{0.0225}{2}=0.01125moles[/tex]
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
- For butanoic acid:
Mass of butanoic acid = 2.002 g
Molar mass of butanoic acid = 88 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of butanoic acid}=\frac{2.002g}{88g/mol}=0.02275mol[/tex]
- For L-tartaric acid:
Mass of L-tartaric acid = 2.002 g
Molar mass of L-tartaric acid = 150 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of L-tartaric acid}=\frac{2.002g}{150g/mol}=0.0133mol[/tex]
- For ascorbic acid:
Mass of ascorbic acid = 2.002 g
Molar mass of ascorbic acid = 176 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of ascorbic acid}=\frac{2.002g}{176g/mol}=0.01137mol[/tex]
As, the number of moles of butanoic acid and ascorbic acid is equal to the number of moles of acid getting neutralized.
Hence, the identity of the unknown acid is butanoic acid or ascorbic acid.
The unknown acid can be butanoic or ascorbic acid.
Determination of the unknown acid:
Based on the given information, the molarity of NaOH is 0.570 M.
The volume of NaOH is 39.55 ml or 39.55 × 10⁻³ L.
Now the number of moles can be determined as,
n = Molarity × Volume of solution in L
Now putting the values we get,
n = 0.570 M × 39.55 × 10⁻³ L
n = 0.0225 moles
Thus, the number of hydroxide ions present in NaOH is 0.0225 moles, therefore, the unknown sample should comprise 0.0225 moles of hydrogen ions or H+ ions.
In case, if it is monoprotic acid, the number of moles of acid = 0.0225 moles
If it is a diprotic acid, the number of moles of acid = 0.0225/2 moles = 0.01125 moles
Now the mass of unknown sample is 2.002 grams.
The formula to determine the molecular mass is,
[tex]Molecular mass = \frac{Weight}{Moles}[/tex]
If it is monoprotic, the molecular mass will be,
[tex]Molecular mass = \frac{2.002 g}{0.0225 moles} \\Molecular mass = 88.977 g/mol[/tex]
If it is diprotic, the molecular mass will be,
[tex]Molecular mass = \frac{2.002 g}{0.01125 moles} \\Molecular mass = 177.955 g/mol[/tex]
Now it is known that the molecular mass of butanoic acid is 88.11 g/mol and the molecular mass of ascorbic acid is 176.12 g/mol. Thus, it can considered that the unknown acid can either be butanoic acid or ascorbic acid.
Find out more information about the identification of an unknown acid here:
https://brainly.com/question/20714816
