Question

A solution is prepared by dissolving 16.2 g of benzene (C₆H₆) in 282 g of carbon tetrachloride

(CCl₄). The concentration of benzene in this solution is __________ molal. The molar masses of
C₆H₆ and CCl₄ are 78.1 g/mol and 154 g/mol, respectively.
A) 0.736
B) 0.0543
C) 7.36 ×10-4
D) 0.102
E) 5.43

Answer 1

Answer: (A)

The concentration of benzene in the solution is 0.736 molal.

To solve the problem, we need to first calculate the moles of benzene and carbon tetrachloride in the solution:

moles of C6H6 = mass / molar mass = 16.2 g / 78.1 g/mol = 0.2075 mol
moles of CCl4 = mass / molar mass = 282 g / 154 g/mol = 1.831 mol

Next, we need to calculate the mass of the solvent (CCl4) in kilograms:

mass of CCl4 = 282 g = 0.282 kg

Finally, we can calculate the molality of the solution:

molality = moles of solute / mass of solvent (in kg) = 0.2075 mol / 0.282 kg = 0.736 mol/kg

Therefore, the answer is A) 0.736.