When 3.10 g of a nonelectrolyte solute is dissolved in water to make 755 mL of solution at 26 °C, the solution exerts an osmotic pressure of 821 torr.
What is the molar concentration of the solution?
How many moles of solute are in the solution?
What is the molar mass of the solute?
pi = nRT
pi = 821/760
Substitute R and T (remember T must be in kelvin) and solve for n.
Then n = grams/molar mass. You know n and grams, solve for molar mass.
M = mols/L solution.
To find the molar concentration of the solution, you need to use the formula for osmotic pressure:
π = (n/V)RT
Where:
π is the osmotic pressure,
n is the number of moles of solute,
V is the volume of the solution in liters,
R is the ideal gas constant (0.0821 L•atm/mol•K),
T is the temperature in Kelvin.
First, we need to convert the given values to the appropriate units:
The mass of the solute is given as 3.10 g.
The volume of the solution is given as 755 mL, which is equal to 0.755 L.
The temperature is given as 26 °C, which needs to be converted to Kelvin. To convert from Celsius to Kelvin, you can use the formula K = °C + 273.
Now, let's calculate the molar concentration of the solution:
1. Convert the temperature from Celsius to Kelvin:
T = 26 °C + 273 = 299 K
2. Plug in the given values into the osmotic pressure formula:
821 torr = (n/0.755 L) * 0.0821 L•atm/mol•K * 299 K
3. Rearrange the formula to solve for n (number of moles of solute):
n = (821 torr * 0.755 L) / (0.0821 L•atm/mol•K * 299 K)
4. Calculate n:
n = 0.240 mol
The molar concentration of the solution is given by the number of moles of solute divided by the volume of the solution in liters:
Molar concentration (M) = n/V
5. Calculate the molar concentration:
M = 0.240 mol / 0.755 L
Now, to find the number of moles of solute and the molar mass of the solute, we need additional information.