Calculate the mole fraction of ethanol in 95% by mass aqueous solution.Mol. mass of ethanol is 46.
95% by mass ethanol means 95 g ethanol in 100 g total. 100 g total-5g ethanol = 95 g H2O.
mols ethanol = grams/molar mass = ?
mols H2O = grams/molar mass
total mols = mols ethanol + mols H2O
Xethanol = mol ethanol/total mols.
Post your work if you get stuck.
To calculate the mole fraction of ethanol in a 95% by mass aqueous solution, we need to consider the masses of both ethanol and water in the solution.
Let's assume we have 100 grams of the solution. This means that 95 grams of the solution are ethanol and the remaining 5 grams are water.
Now, let's calculate the number of moles of ethanol in the solution. We can do this by dividing the mass of ethanol (95 grams) by the molar mass of ethanol (46 g/mol):
Number of moles of ethanol = Mass of ethanol / Molar mass of ethanol
Number of moles of ethanol = 95 g / 46 g/mol
The molar mass of ethanol is given as 46 g/mol. Therefore,
Number of moles of ethanol = 2.065 moles
Next, let's calculate the mass of water in the solution. Since the total mass of the solution is 100 grams and the mass of ethanol is 95 grams, the mass of water can be found by subtracting:
Mass of water = Total mass of solution - Mass of ethanol
Mass of water = 100 g - 95 g
Mass of water = 5 g
Now, let's calculate the number of moles of water. We can do this by dividing the mass of water (5 grams) by the molar mass of water (18 g/mol):
Number of moles of water = Mass of water / Molar mass of water
Number of moles of water = 5 g / 18 g/mol
The molar mass of water is 18 g/mol. Therefore,
Number of moles of water = 0.278 moles
Finally, let's calculate the mole fraction of ethanol by dividing the number of moles of ethanol by the total number of moles in the solution (ethanol + water):
Mole fraction of ethanol = Number of moles of ethanol / (Number of moles of ethanol + Number of moles of water)
Mole fraction of ethanol = 2.065 moles / (2.065 moles + 0.278 moles)
Mole fraction of ethanol = 0.881
Therefore, the mole fraction of ethanol in the 95% by mass aqueous solution is 0.881.