What is the mole fraction of #KI# in a solution made by dissolving 3.4 g of #KI# in 5.8 g of water?

Question

Naomi Aronson · Accepted Answer

#"Mole fraction"# #=# #"Moles of component"/"Moles of all species in solution"# And thus, #"Mole fraction, KI"# #=# #"Moles of KI"/"Moles of KI + moles of water"# #=((3.4*g)/(166.00*g*mol^-1))/((3.4*g)/(166.00*g*mol^-1)+(5.8*g)/(18.01*g*mol^-1))# #=# #0.060# Note that the mole fraction of #"water"# here must be necessarily #1-0.060=0.94#. Why #"necessarily"#? Note that #"mole fractions"#, as they are here, are dimensionless quantities.

Caleb Adams · Answer

undefined To find the mole fraction of KI in the solution, you first need to calculate the number of moles of KI and water separately. Then, you divide the moles of KI by the total moles of solute (KI) and solvent (water) combined.

1. Calculate the moles of KI:
   - Molar mass of KI = 39.10 g/mol (for K) + 126.90 g/mol (for I) = 166.00 g/mol
   - Moles of KI = mass / molar mass = 3.4 g / 166.00 g/mol = 0.0205 mol

2. Calculate the moles of water:
   - Molar mass of water (H₂O) = 2(1.01 g/mol) + 16.00 g/mol = 18.02 g/mol
   - Moles of water = mass / molar mass = 5.8 g / 18.02 g/mol = 0.322 mol

3. Calculate the total moles of solute and solvent:
   - Total moles = moles of KI + moles of water = 0.0205 mol + 0.322 mol = 0.3425 mol

4. Calculate the mole fraction of KI:
   - Mole fraction of KI = moles of KI / total moles = 0.0205 mol / 0.3425 mol ≈ 0.060

So, the mole fraction of KI in the solution is approximately 0.060.