A 1.213g sample of an unknown weak monoprotic acid was titrated to the endpoint with 27.25mL of a 0.3016M NaOH Calculate:
-the number of moles of base reacted.
-the number of moles of acid originally present.
-the molar mass of the acid.
mols base = M x L = ?
For a monoprotic acid mols acid = mols base
mols acid = grams acid/molar mass. You know mols and grams, solve for molar mass.
To solve this problem, we'll use the balanced chemical equation for the reaction between the acid and NaOH, as well as the given information.
First, let's determine the moles of base reacted.
We're given the volume and concentration of NaOH:
Volume of NaOH = 27.25 mL = 0.02725 L
Concentration of NaOH = 0.3016 M
Using the formula:
moles of base = volume × concentration
moles of base = 0.02725 L × 0.3016 M
moles of base = 0.0082286 mol
Next, we'll find the moles of acid originally present.
Since the acid is monoprotic, the ratio between moles of acid and moles of base is 1:1 according to the balanced equation. Therefore, the moles of acid will also be 0.0082286 mol.
Lastly, we'll determine the molar mass of the acid.
We're given the mass of the acid sample:
Mass of acid = 1.213 g
Using the formula:
moles = mass / molar mass
molar mass = mass / moles
molar mass = 1.213 g / 0.0082286 mol
molar mass ≈ 147.38 g/mol
Therefore, the molar mass of the acid is approximately 147.38 g/mol.
To calculate the number of moles of base reacted, you need to use the equation:
moles of base = volume of base (in L) x molarity of base
Given:
Volume of base = 27.25 mL = 27.25/1000 L (convert mL to L)
Molarity of base = 0.3016 M
Calculating the moles of base:
moles of base = 27.25/1000 L * 0.3016 M = 0.0082308 moles
Next, to determine the number of moles of acid originally present, you need to use the concept of stoichiometry. Since the reaction is monoprotic, it follows a one-to-one ratio between the acid and the base.
Thus, the number of moles of acid is equal to the number of moles of base reacted:
moles of acid = 0.0082308 moles
Finally, you can calculate the molar mass of the acid using the formula:
molar mass (in g/mol) = mass of the acid (in g) / moles of acid
Given:
mass of the acid = 1.213 g
moles of acid = 0.0082308 moles
Calculating the molar mass of the acid:
molar mass = 1.213 g / 0.0082308 moles = 147.2 g/mol
Therefore:
- The number of moles of base reacted is 0.0082308 moles.
- The number of moles of acid originally present is 0.0082308 moles.
- The molar mass of the acid is 147.2 g/mol.