Question

What is the mole fraction of H₃PO₄ in a solution of 14.5 g of H₃PO₄ (97.9952 g/mol) in 125 g of water (18.0153 g/mol)?

A) 0.104
B) 0.0209
C) 0.0213
D) 0.631

Answer 1

To calculate the mole fraction of H3PO4 in a solution, we calculate the moles of H3PO4 and water individually and divide the moles of H3PO4 by the total moles in the solution. After performing the calculations, the mole fraction of H3PO4 is found to be 0.0209.

Step-by-step explanation:

The question asks to calculate the mole fraction of H3PO4 in a solution. To find the mole fraction, we need to find the number of moles of H3PO4 and the number of moles of water, and then divide the number of moles of H3PO4 by the total number of moles in the solution.

1. Calculate the moles of H3PO4 by dividing the mass by its molar mass: moles H3PO4 = 14.5 g / 97.9952 g/mol.
2. Calculate the moles of water by dividing the mass by its molar mass: moles H2O = 125 g / 18.0153 g/mol.
3. Add the moles of H3PO4 and moles of H2O to get total moles in solution.
4. Divide the moles of H3PO4 by the total moles to get the mole fraction of H3PO4.

To calculate the numbers:

• Moles of H3PO4 = 14.5 g / 97.9952 g/mol = 0.1479 moles.
• Moles of H2O = 125 g / 18.0153 g/mol = 6.9386 moles.
• Total moles = 0.1479 moles + 6.9386 moles = 7.0865 moles.
• The mole fraction of H3PO4 = 0.1479 moles / 7.0865 moles = 0.0209.

Hence, the correct answer is B) 0.0209.