If the osmotic pressure of a solution is 3.0 atm at 25 °C, what is the molarity

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Question: If the osmotic pressure of a solution is 3.0 atm at 25 °C, what is the molarity of the solution? (R = 0.0821 L atm/(K mol))

Options:

Correct Answer: 0.18 M

Solution:

Molarity = π / (RT) = 3.0 / (0.0821 * 298) = 0.12 M

If the osmotic pressure of a solution is 3.0 atm at 25 °C, what is the molarity of the solution? (R = 0.0821 L atm/(K mol))

If the osmotic pressure of a solution is 3.0 atm at 25 °C, what is the molarity of the solution? (R = 0.0821 L atm/(K mol))

Step 1: Identify the formula for molarity (M) using osmotic pressure (π): M = π / (RT).
Step 2: Note the values given in the question: π = 3.0 atm, R = 0.0821 L atm/(K mol), and the temperature (T) = 25 °C.
Step 3: Convert the temperature from Celsius to Kelvin: T = 25 + 273 = 298 K.
Step 4: Substitute the values into the formula: M = 3.0 / (0.0821 * 298).
Step 5: Calculate the denominator: 0.0821 * 298 = 24.4758.
Step 6: Divide the osmotic pressure by the calculated value: M = 3.0 / 24.4758.
Step 7: Perform the division to find the molarity: M ≈ 0.12 M.

Osmotic Pressure – Osmotic pressure is the pressure required to prevent the flow of solvent into a solution through a semipermeable membrane, and it is directly related to the molarity of the solution.
Ideal Gas Law – The relationship between pressure, volume, temperature, and number of moles in a gas, which is applied here in the context of solutions using the formula π = MRT.
Molarity Calculation – Molarity is calculated as the number of moles of solute per liter of solution, and in this case, it is derived from the osmotic pressure formula.