What is the molality of a solution composed of 25ml og toluene C6H5CH3 ( density=0.866g/ml) in 75 ml of benzene ( density=0.879g/ml)
For toluene (the solute):
mass = volume x density. Substitute and solve for mass. Then mols = mass toluene/molar mass toluene.
For benzene:
mass = volume x density. Substitute and solve for mass benzene.
Convert mass in g benzene to kg benzene (the solvent).
Then m = mols solute/kg solvent.
To calculate the molality of the solution, we first need to determine the moles of solute (toluene) and the mass of the solvent (benzene).
Step 1: Calculate the moles of toluene (C6H5CH3):
Since we have the volume (25 ml) and the density (0.866 g/ml) of toluene, we can find the mass of toluene using the formula: mass = volume x density.
mass of toluene = 25 ml x 0.866 g/ml
Step 2: Calculate the mass of benzene:
Similarly, we can find the mass of benzene using its density and volume.
mass of benzene = 75 ml x 0.879 g/ml
Step 3: Calculate the molality:
Molality (m) is defined as moles of solute per kilogram of solvent.
To calculate molality, we need to find the moles of toluene and the mass of benzene in kilograms.
moles = mass / molar mass
First, let's find the moles of toluene:
moles of toluene = mass of toluene / molar mass of toluene
The molar mass of toluene (C6H5CH3) can be calculated by summing the atomic masses of its constituent elements:
molar mass of toluene = (6 x atomic mass of carbon) + (5 x atomic mass of hydrogen)
Lastly, divide the moles of toluene by the mass of benzene in kilograms:
molality = moles of toluene / (mass of benzene / 1000)
By following these steps and plugging in the given values, you can calculate the molality of the solution.