Determine the mass of potassium chloride, KCl, that must be added to water to create an aqueous solution of volume 25 dm³ with an osmotic pressure of 1.0 bar.

Question

Quizplus · Accepted Answer

To solve this problem, we can use the formula for osmotic pressure of an ideal solution:

π = MRT

where π is the osmotic pressure, M is the molarity of the solution, R is the gas constant, and T is the temperature in kelvin.

We can rearrange this formula to solve for the molarity, M:

M = π / RT

We know the volume of the solution is 25 dm3, or 0.025 m3. We also know the osmotic pressure is 1.0 bar. The temperature is not given, so we can assume it is at standard temperature of 273 K.

The molarity of the solution can be found using the formula above:

M = (1.0 bar) / (0.083 L bar/K mol x 273 K)

M = 0.0459 mol/L

Now we can use this molarity to find the mass of KCl needed to make the solution. The molecular weight of KCl is 74.6 g/mol.

mass = moles x molecular weight

mass = 0.0459 mol/L x 25 L x 74.6 g/mol

mass = 75.3 g

Therefore, the answer is D) 75.3 g.

Determine the Mass of Potassium Chloride, KCl, That Must Be