Question

You are given 450.0 g of a 0.7500 molal solution of acetone dissolved in water. how many grams of acetone are in this amount of solution?

Answer 1

To find the grams of acetone in the given solution, we can use the formula for molality and calculate the mass of acetone based on the molality, molar mass of acetone, and mass of the solvent.

Step-by-step explanation:

The mass of the solution is given as 450.0 g and the molality is given as 0.7500 molal. To find the grams of acetone in the solution, we can use the formula for molality:

Molality (m) = moles of solute / mass of solvent (in kg)

Since 0.7500 molal corresponds to 0.7500 mol of acetone per 1 kg of water, we can calculate the mass of acetone by multiplying the molality by the molar mass of acetone and the mass of the solvent:

Mass of acetone = 0.7500 molal * (58.08 g/mol) * (0.4500 kg)

Therefore, there are 22.52 grams of acetone in this amount of solution.

Answer 2

Molality is the number of moles dissolved in one kilogram of solvent.
m = n/kg of solvent
n = mass of solute / molar mass of solute
Acetone's chemical formula is C3H6O. Therefore, its molar mass = 12*3 + 6*1 + 1*16 = 58g = 0.058kg
n = mass of solute / 0.058
We have the molality = 0.7500 and the mass of solution = mass of solvent + mass of solute = 450 g = 0.45 kg
Therfore, mass of solvet = 0.45 - mass of solute
0.75 = n / 0.45 - mass of solute
0.75 = (mass of solute / 0.058) / (0.45 - mass of solute)
Let mass of solute = x
0.75 = (x/0.058) / (0.45 - x)
0.3375 - 0.75x = x/0.058
x = 0.019575 - 0.0435x
1.0435x = 0.019575
x = 0.01875 kg
mass of acetone = 0.01875 kg = 18.75 grams