2) Toluene, C6H5CH3, is a liquid similar to benzene, C6H6. It is the starting material for other substances, including trinitrotoluene (TNT). Find the molality of toluene in a solution that contains 25.8 g of toluene and 135 g of benzene.
molality = m = mols/kg solvent
mols toluene = 25.8g/molar mass toluene.
kg solvent = 0.135.
To find the molality of toluene in the solution, we need to calculate the moles of toluene and the mass of benzene.
Step 1: Calculate the moles of toluene using its molar mass.
The molar mass of toluene (C6H5CH3) can be calculated by adding up the atomic masses of its elements:
C = 12.01 g/mol x 7 atoms = 84.07 g/mol
H = 1.01 g/mol x 8 atoms = 8.08 g/mol
Total molar mass of toluene = 84.07 g/mol + 8.08 g/mol = 92.15 g/mol
To calculate the moles of toluene, we divide the mass of toluene by its molar mass:
Moles of toluene = 25.8 g / 92.15 g/mol
Step 2: Calculate the mass of benzene.
Given: Mass of benzene = 135 g
Step 3: Calculate the molality of toluene.
Molality is defined as the moles of solute per kilogram of solvent. To calculate it, we need to convert the mass of benzene to kilograms.
Mass of benzene in kg = 135 g / 1000 (1 kg = 1000 g)
Now, we can calculate the molality using the formula:
Molality = Moles of toluene / Mass of benzene in kg
Substitute the calculated values:
Molality = (25.8 g / 92.15 g/mol) / (135 g / 1000 kg)
Finally, calculate the molality to obtain the answer.