A solution was made by dissolving 62.07 grams of a compound in 500.0 g of water. The compound was not ionic. The freezing point of the solution was measured and found to be – 1.86oC. Using the Kf value in your textbook , the molar mass of this compound can be calculated to be
a) 57.7 g/mol
b) 124 g/mol
c) 231 g/mol
d) 62.1 g/mol
e) 115 g/mol
bet its e
If you were betting you lost.
delta T = i*Kf*m
You know dT, i = 1, and Kf. Solve for molality.
Molality = moles/kg solvent.
You have m and kg solvent, solve for moles.
moles solute = n = grams solute/molar mass solute.
You know moles and grams, solve for molar mass.
still lost :(
To calculate the molar mass of the compound, we need to use the equation for freezing point depression:
ΔTf = Kf * m
Where:
ΔTf = the change in freezing point of the solution (in degrees Celsius)
Kf = the cryoscopic constant for the solvent
m = molality of the solution (moles of solute per kg of solvent)
First, let's calculate the molality of the solution:
molality (m) = moles of solute / kg of solvent
The moles of solute can be calculated by dividing the mass of the compound by its molar mass:
moles of solute = mass of compound / molar mass
mass of compound = 62.07 g
Now, we need to find the kg of solvent to calculate molality. Since the mass of water is given in grams, we need to convert it to kilograms:
mass of water = 500.0 g = 0.5000 kg
Now we can calculate the molality:
molality = (62.07 g) / (molar mass) / (0.5000 kg)
Now, let's plug the values into the ΔTf equation:
ΔTf = Kf * (molality)
The freezing point depression, ΔTf, is given as -1.86°C.
-1.86 = Kf * (molality)
Finally, we can solve for the molar mass:
molar mass = (62.07 g) / [Kf * (molality)]
Since the value of Kf is not given, you need to consult your textbook to find the appropriate value for the solvent used in the experiment. Once you have the Kf value, you can calculate the molar mass using the equation above.