Final answer:
The molar mass of the diprotic acid H2X was determined by titrating it with NaOH and calculating the moles of each reactant. The molar mass was found to be 220 g/mol after rounding to three significant figures.
Step-by-step explanation:
To determine the molar mass of the diprotic acid H2X that reacts completely with a NaOH solution, we start by calculating the number of moles of NaOH used in the titration. The concentration and volume of NaOH are given, so we can calculate the moles of NaOH:
Number of moles of NaOH = concentration of NaOH (M) × volume of NaOH (L)
= 0.350 M × 0.0467 L
= 0.016345 moles
Since H2X is a diprotic acid, each mole of the acid will react with two moles of NaOH.
Therefore, the number of moles of H2X that reacted will be half the moles of NaOH reacted:
Number of moles of H2X = 0.016345 moles NaOH × (1 mole H2X / 2 moles NaOH)
= 0.0081725 moles
To find the molar mass of H2X, we use the mass of the acid sample and the number of moles we just calculated:
Molar mass of H2X = mass of H2X (g) / number of moles of H2X
= 1.80 g / 0.0081725 moles
= 220.1 g/mol
The molar mass of H2X, rounded to three significant figures, is 220 g/mol.