For each trial, compute the mol of titrant; (molarity x L) and keep the number of significant figures to 4.

Trial 1: 12.49 mL =
mol NaOH
Trial 2: 12.32 mL =
mol NaOH
Trial 3: 11.87 mL =
mol NaOH

Trial     Number of moles

  1          0.001249mol

  2         0.001232mol

  3          0.001187 mol

Explanation:

To calculate the number of moles of tritant you need its molarity.

Since the molarity is not reported, I will use 0.1000M (four significant figures), which is used in other similar problems.

Molarity is the concentration of the solution in number of moles of solute per liter of solution.

In this case the solute is NaOH.

The formula is:

Solve for the number of moles:

Then, using the molarity of 0.1000M and the volumes for each trial you can calculate the number of moles of tritant.

Trial    mL           liters          Number of moles

1          12.49       0.01249        0.01249liters × 0.1000M = 0.001249mol

2         12.32      0.01232         0.01232liters × 0.1000M = 0.001232mol

3          11.87       0.01187         0.01187liters × 0.1000M = 0.001187 mol