Answer:
0.105 KCl
Explanation:
(Step 1)
If the solution is 32.7% KCl, we can assume that there are 32.7 grams KCl in the solution. This means that there would be 67.3 grams H₂O (100% - 32.7% = 67.3%) in the solution.
32.7% KCl = 32.7 g KCl
67.3% H₂O = 67.3 g H₂O
(Step 2)
Now, we need to convert both the solute (KCl) and the solvent (H₂O) into moles. This can be done by multiply the grams of each substance by their molar masses.
32.7 g KCl 1 mole
------------------ x -------------------- = 0.439 mole KCl
74.55 g
67.3 g H₂O 1 mole
------------------ x ----------------- = 3.74 moles H₂O
18.016 g
(Step 3)
Finally, we can calculate the mole fraction of KCl using the following equation. The final answer should have 3 sig figs to match the given value with the lowest amount of sig figs (32.7 g).
moles of solute
Mole Fraction = -----------------------------------------------------
moles of solute + moles of solvent
0.439 mole KCl
Mole Fraction = ------------------------------------------------------
0.439 mole KCl + 3.74 moles H₂O
Mole Fraction = 0.105 KCl
