Question

What is the osmotic pressure, in atmospheres, of a 0.75 L solution of 0.83 g of ethanol, C2H6O, in water at 30∘C? Use R=0.08206L atmmol K for the gas constant Select the correct answer below: 0.45 atm 0.60 atm 0.81 atm 0.7 atm

Answer 1

To calculate the osmotic pressure, we find the molarity of the solution by dividing the number of moles of ethanol by the volume of the solution. Then, we use the osmotic pressure formula with the gas constant and the temperature in Kelvin. The osmotic pressure is approximately 0.60 atm.

Step-by-step explanation:

The osmotic pressure of a solution can be calculated using the formula Π = MRT, where Π is the osmotic pressure in atm, M is the molarity of the solution in mol/L, R is the gas constant, and T is the temperature in Kelvin. To find the molarity, we first need to determine the number of moles of ethanol, C2H6O, which is given by the mass of ethanol divided by its molar mass. Using the information provided:

• Mass of ethanol = 0.83 g
• Molar mass of ethanol (C2H6O) = 2(12.01) + 6(1.008) + 16.00 = 46.068 g/mol
• Moles of ethanol = 0.83 g / 46.068 g/mol = 0.018 mol
• Molarity (M) = moles of solute / liters of solution = 0.018 mol / 0.75 L = 0.024 M
• Temperature (T) = 30°C = 30 + 273.15 = 303.15 K

Now, we can substitute these values into the osmotic pressure equation:

Π = (0.024 mol/L)(0.08206 L atm/mol K)(303.15 K) = 0.593 atm

Therefore, the osmotic pressure of this solution is approximately 0.60 atm.

Answer 2

0.60 atm

Step-by-step explanation:

The osmotic pressure of the solution is given by Π=MRT, where M is the solute molarity, T is the absolute temperature, and R is the universal gas constant.

In this case, the absolute temperature is 273 K+30 C=303 K.

The molar mass of ethanol is 46.07 g/mol, so the solution contains 0.83 g/46.07 g mol−1=0.018 moles of ethanol.

The molarity of the solute is 0.018 mol/0.75 L=0.024 mol/L.

Thus, the osmotic pressure is as shown below when rounded to two significant figures.

Π=MRT=0.024 mol/L×0.08206 L atm/mol K×303 K=0.60 atm