At a certain temperature a 43.32% (v/v) solution of ethyl alcohol, C2H5OH, in wa
ID: 481199 • Letter: A
Question
At a certain temperature a 43.32% (v/v) solution of ethyl alcohol, C2H5OH, in water has a density of 0.9031 g mL-1. The density of ethyl alcohol at this temperature is 0.7907 g mL-1, and that of water is 0.9890 g mL-1.
Calculate the molar concentration of ethyl alcohol.
Calculate the molal concentration of ethyl alcohol.
Calculate the mole fraction of ethyl alcohol in the solution.
If the vapor pressure of ethyl alcohol at this temperature is 41.0 torr and the solution is ideal, what is the pressure of ethyl alcohol above this solution?
If the vapor pressure of water at this temperature is 17.5 torr and the solution is ideal, what is the pressure of water above this solution?
Explanation / Answer
Calculate the molar concentration of ethyl alcohol.
M = mol/V
find, mass of ethyl alcohol:
Assume a basis of 1 Liter solution
Volume of Alcohol = %V * Vmix = 43.32/100*1000 = 433.2 mL is ethanol
so
mass = D*V = 433.2 *0.7907 = 342.53124 g of ethanol
mol = mass/MW = 342.53124/46 = 7.446 mol of ethanol
M = mol/V = 7.446 / 1 = 7.446 M
Calculate the molal concentration of ethyl alcohol.
Molal = mol of Solute / kg solvent
so..
mol of solute (ethanol) = 7.446
find mass of solvent
so
mass of solvent (1liter) = D*V = 1000*0.9031 = 903.1 g of mix
of those,
mass of water = 903.1 - 342.53124 = 560.568 g of water = 0.560568 kg
so
molality = 7.446 /0.560568 = 13.282 molal
Calculate the mole fraction of ethyl alcohol in the solution.
mol of ethanol = 7.446
mol of water = mass/MW = 560.568 /18 = 31.142 mol of water
total mol = 7.446+31.142 = 38.588
x-ethanol = mol of ethanol / total mol = 7.446/38.588 = 0.1929
Please consider posting multiple questions in multiple set of Q&A. According to Chegg's Q&A Guidelines, we are only allowed to answer to one questions per Q&A.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.