A solution is prepared by dissolving 5.00g of an unknown molecular solid in water to make 500 ml of solution. The osmotic pressure of the solution is 1.61 atm at 25 degrees C. What is the molar mass of the solute?
This is what ive done so far:
M= 1.61atm/(0.0821Lxatm/molxK)(298K)= 0.0658mol/L
Whats should i do next?
multiply by the volume, to get moles.
molar mass= mass/#moles
Thanks I just figured it out too. I appreciate your help.
To find the molar mass of the solute, you can use the formula:
Molar mass (g/mol) = mass of solute (g) / number of moles of solute (mol)
Given that the concentration of the solution is 0.0658 mol/L, you can calculate the number of moles of solute by multiplying the concentration by the volume of solution:
Number of moles of solute (mol) = concentration (mol/L) x volume of solution (L)
Number of moles of solute = 0.0658 mol/L x 0.500 L = 0.0329 mol
Now, you can calculate the molar mass of the solute using the formula:
Molar mass (g/mol) = mass of solute (g) / number of moles of solute (mol)
Rearranging the formula, you get:
Mass of solute (g) = molar mass (g/mol) x number of moles of solute (mol)
Since you have the mass of the solute (5.00 g), you can rearrange the formula to solve for the molar mass:
Molar mass (g/mol) = mass of solute (g) / number of moles of solute (mol)
Molar mass = 5.00 g / 0.0329 mol
Molar mass = 152 g/mol
Therefore, the molar mass of the solute is 152 g/mol.
To find the molar mass of the solute, you need to use the formula for osmotic pressure:
π = MRT
Where:
π = osmotic pressure
M = molarity of the solution (in mol/L)
R = ideal gas constant (0.0821 L·atm/mol·K)
T = temperature in Kelvin (298K)
You have already found the molarity (M) to be 0.0658 mol/L. Now, rearrange the formula to solve for M:
M = π / (RT)
Substitute the given values into the equation:
M = 1.61 atm / (0.0821 L·atm/mol·K * 298 K) = 0.0658 mol/L
Now that you have the molarity, you can calculate the number of moles of the solute in the solution:
moles = molarity x volume
moles = 0.0658 mol/L x 0.5 L = 0.0329 mol
Finally, to find the molar mass (Mm) of the solute, divide the mass of the solute by the number of moles:
Mm = mass / moles
Mm = 5.00 g / 0.0329 mol ≈ 151.98 g/mol
Therefore, the molar mass of the solute is approximately 151.98 g/mol.