Calculate the mass ( g ) of the solute ethanol and the mass ( kg ) of the solvent CHCl3 that should be combined to prepare 9900 g of a solution that is 14.5 m ethanol.
extra given info from problem:
molar mass (g/mol):
C2H5OH 46.07
CHCl3 119.38
density (kg/L):
C2H5OH 0.7893
CHCl3 1.483
Check my work. It's late.
You want 9900 grams of 14.5 m solution of EtOH.
Suppose we wanted to prepare a 14.5 M solution the usual way. We would weigh out 145 moles EtOH and 10,000 g water (10 Kg). (Note that 145 moles/10 kg solvent = 14.5 m.) How much would that SOLUTION weigh? It will have a mass of 10,000 g for the water + the mass of 145 moles EtOH. 145 mols = 145 x 46.07 = 6680.15 g ( I know that's too many places but we can round at the end.)
The total mass of the solution will be 16,680.15 grams.
Now to the solution we want to prepare. We want the SOLUTION to be 9900 grams. So how many mols will be in that mass?
6680.15 x (9900/16680.15) = 3964.8 g EtOH. How much water? That will be
9900-3964.8 = 5935.2 g.
Will that do it?
3964.8 g EtOH = 3964.8/46.07 = 86.06 moles. m = 86.06 moles EtOH/5.9352 kg water = 14.4999 which rounds to 14.5 m.
To solve this problem, we need to determine the mass of ethanol and the mass of CHCl3 required to prepare a 9900 g solution that is 14.5 m ethanol.
First, let's calculate the number of moles of ethanol needed using the given molarity (14.5 m) and the total volume of the solution (9900 g).
Molarity (M) is defined as the number of moles of solute per liter of solution. Since the density of ethanol is given in kg/L, we can convert the total mass of the solution (9900 g) to volume (in liters) using the density of ethanol.
Step 1: Calculate the total volume of the solution in liters
Total volume (L) = Total mass (g) / Density (kg/L)
Total volume (L) = 9900 g / 0.7893 kg/L
Step 2: Calculate the moles of ethanol
Moles of ethanol = Molarity (M) * Total volume (L)
Moles of ethanol = 14.5 * (9900 g / 0.7893 kg/L)
Next, let's calculate the mass of ethanol and the mass of CHCl3.
Step 3: Calculate the mass of ethanol
Mass of ethanol (g) = Moles of ethanol * Molar mass of ethanol (g/mol)
Mass of ethanol (g) = moles of ethanol * 46.07 g/mol
Finally, let's calculate the mass of CHCl3.
Step 4: Calculate the mass of CHCl3
Since we know the total mass of the solution (9900 g), we can subtract the mass of ethanol to find the mass of CHCl3.
Mass of CHCl3 (g) = Total mass of the solution (g) - Mass of ethanol (g)
Remember to convert the mass of CHCl3 to kg since it is given in kg/L.
Step 5: Convert the mass of CHCl3 to kg
Mass of CHCl3 (kg) = Mass of CHCl3 (g) / 1000
By following these steps, you can calculate the mass of the solute (ethanol) and the mass of the solvent (CHCl3) needed to prepare the desired solution.