A student completes a titration of an unknown diprotic acid. In this experiment, 0.79 g of the acid is dissolved in 250.0 mL of water. It requires 13.48 mL of 1.0 M NaOH to reach the second equivalence point. What is the molar mass of the acid?

H2A + 2NaOH ==> Na2A + 2H2O

mols NaOH = M x L = ?
mols H2A = 1/2 x mols NaOH (look at the coefficients in the balanced equation).
Then mols H2A = grams H2A/molar mass H2A. You know mols and grams, solve for molar mass.

To find the molar mass of the diprotic acid, we need to follow these steps:

Step 1: Calculate the number of moles of NaOH used.
- We know that the volume of NaOH used is 13.48 mL, which is equivalent to 0.01348 L.
- The concentration of NaOH is 1.0 M, which means there is 1 mole of NaOH per 1 liter of solution.
- Therefore, the number of moles of NaOH used can be calculated as follows:
Moles of NaOH = Concentration of NaOH × Volume of NaOH used
= 1.0 M × 0.01348 L

Step 2: Determine the number of moles of diprotic acid used.
- From the balanced chemical equation of the reaction, we know that each mole of NaOH reacts with one mole of the diprotic acid.
- Therefore, the number of moles of the diprotic acid used will be the same as the number of moles of NaOH used.

Step 3: Calculate the molar mass of the diprotic acid.
- We know the mass of the diprotic acid used is 0.79 g, and the number of moles is determined as mentioned in the previous step.
- The molar mass of the acid can be calculated using the following formula:
Molar mass of acid = Mass of acid used / Moles of acid used

Let's calculate the molar mass of the diprotic acid based on these steps:

Step 1:
Moles of NaOH = 1.0 M × 0.01348 L = 0.01348 moles of NaOH

Step 2:
Moles of diprotic acid used = 0.01348 moles of acid

Step 3:
Molar mass of the acid = 0.79 g / 0.01348 moles of acid

By performing this calculation, we can find the molar mass of the diprotic acid.

To find the molar mass of the acid, we need to use the information given and the concept of titration.

1. First, let's start by calculating the number of moles of NaOH used in the titration. We know the volume of NaOH used is 13.48 mL and its concentration is 1.0 M.

To do this, we use the formula:
Number of moles = Concentration (M) × Volume (L)

Converting the volume to liters:
13.48 mL = 13.48 / 1000 L = 0.01348 L

Substituting the values into the formula:
Number of moles of NaOH = 1.0 M × 0.01348 L = 0.01348 moles

2. Now, let's determine the number of moles of acid required to react with the NaOH. Since NaOH is a strong base and the acid is diprotic, two moles of NaOH react with one mole of the acid at the second equivalence point.

Number of moles of acid = 1/2 × Number of moles of NaOH
= 1/2 × 0.01348 moles
= 0.00674 moles

3. Next, we can calculate the molar mass of the acid using the formula:

Molar mass (g/mol) = Mass (g) / Number of moles

The given mass of the acid is 0.79 g, and we calculated the number of moles as 0.00674 moles.

Molar mass of the acid = 0.79 g / 0.00674 moles = 117.2335 g/mol

Therefore, the molar mass of the unknown diprotic acid is approximately 117.23 g/mol.