Question

A solution is prepared by dissolving 74.2 g NaI in 527 g of water. Determine the mole fraction of NaI if the final volume of the solution is 565 mL.

a. 8.84 times 10^-2
b. 1.40 times 10^-3
c. 6.04 times 10^-3
d. 1.32 times 10^-2
e. 1.65 times 10^-2

Answer 1

The correct answer is option e, that is, 1.65 * 10^-2.

Step-by-step explanation:

Based on the given information, the weight of NaI given is 74.2 grams and the weight of water given is 527 grams.

The final volume of the solution given is 566 ml.

The formula to calculate the moles is weight/molecular mass,

The moles of NaI will be,

= 74.2/150 = 0.494

Now moles of water will be,

= 527/18 = 29.3

The mole fraction of NaI will be,

= 0.494 / (0.494 + 29.3)

= 0.0165 or 1.65 * 10^-2

Hence, the mole fraction of NaI is 1.65 * 10^-2