A 0.753 m solution of the solute CH3CN dissolved in the solvent C6H6 is available. Calculate the mass ( g ) of the solution that must be taken to obtain 3.274 mol of CH3CN.
Additional info:
Molar Mass (g/mol)
CH3CN 41.05
C6H6 78.11
Density ( kg/L )
CH3CN 0.7857
C6H6 0.8786
Name/Formula
acetonitrile
CH3CN
benzene
C6H6
There's the quick way and the long way.
Quick way:
m = moles/kg solvent
0.753 = 3.274/kg solvent.
Solve for kg solvent, then add mass of 3.274 moles CH3CN to find the total mass of the solution needed.
To calculate the mass of the solution needed to obtain a certain number of moles of CH3CN, follow these steps:
Step 1: Calculate the molar mass of CH3CN.
The molar mass of CH3CN is 41.05 g/mol.
Step 2: Convert the number of moles of CH3CN to grams.
To do this, use the equation:
mass (g) = number of moles × molar mass (g/mol)
mass (g) = 3.274 mol × 41.05 g/mol
mass (g) = 134.5347 g
Step 3: Calculate the mass of the solution.
The solution is comprised of both the solute (CH3CN) and the solvent (C6H6). To determine the mass of the solution, we need to calculate the mass of both components separately and add them together.
3.274 mol of CH3CN is dissolved in 1 L of solution, so the total volume of the solution is 1 L.
To calculate the mass of CH3CN in the solution, use the equation:
mass of CH3CN (g) = volume (L) × density (kg/L) × 1000 (g/kg)
mass of CH3CN (g) = 1 L × 0.7857 kg/L × 1000 (g/kg)
mass of CH3CN (g) = 785.7 g
To calculate the mass of C6H6 in the solution, use the equation:
mass of C6H6 (g) = volume (L) × density (kg/L) × 1000 (g/kg)
mass of C6H6 (g) = 1 L × 0.8786 kg/L × 1000 (g/kg)
mass of C6H6 (g) = 878.6 g
Therefore, the mass of the solution is the sum of the masses of CH3CN and C6H6:
mass of solution (g) = mass of CH3CN (g) + mass of C6H6 (g)
mass of solution (g) = 785.7 g + 878.6 g
mass of solution (g) = 1664.3 g
So, you need to take approximately 1664.3 grams of the solution to obtain 3.274 moles of CH3CN.