Question

A solution contains 4 g of NaOH and 16.2 g of water. The mole fraction solute and solvent are respectively

• A. 0.1, 0.9
• B. 0.2, 0.8
• C. 0.5, 0.5
• D. 0.4, 0.6

Answer 1

The Correct Option is A

Answer (A) 0.1, 0.9 

To calculate the mole fraction of a solute and solvent in a solution, we need to determine the number of moles of each component.

Given: Mass of NaOH = 4 g Mass of water = 16.2 g

To find the number of moles of NaOH, we divide the given mass by the molar mass of NaOH. Molar mass of NaOH = 22.99 g/mol (for Na) + 16.00 g/mol (for O) + 1.01 g/mol (for H) = 39.99 g/mol Number of moles of NaOH = 4 g / 39.99 g/mol ≈ 0.1 mol

To find the number of moles of water, we divide the given mass by the molar mass of water. Molar mass of water (H₂O) = 1.01 g/mol (for H) + 1.01 g/mol (for H) + 16.00 g/mol (for O) = 18.02 g/mol Number of moles of water = \(\frac {16.2\  g }{18.02\  g/mol}\) ≈ 0.9 mol

Now, we can calculate the mole fraction of solute (NaOH) and solvent (water).

Mole fraction of solute (NaOH) = \(\frac {Moles\  of \ NaOH}{Total \ moles }\)= \(\frac {0.1\  mol}{(0.1\  mol + 0.9\  mol) }\) = 0.1

Mole fraction of solvent (water) = \(\frac {moles \ of \ water}{Total \ moles}\) = \(\frac {0.9 \ mol}{(0.1\  mol + 0.9\  mol) }\)= 0.9

Therefore, the mole fraction of solute (NaOH) and solvent (water) in the given solution are approximately 0.1 and 0.9, respectively. So the correct option is 0.1, 0.9.