Question

9) An ethanol-water solution is 40.00% ethanol by mass and has a density of 0.9450 (g/cm3) at 25.00°C. The density of pure ethanol is 0.7850 (g/cms) and the density of pure water is 0.9970(g/cms) at this temperature. At these conditions, the partial molar volume of ethanol is 55.00 (cm3/mol) and the partial molar volume of water is 17.5 (cmmol). a. Calculate the total volume of a 1000.0 g solution assuming both ideal and non-ideal conditions. b. What does the difference between the volumes calculated in Part a, tell you about the interactions between the water and ethanol molecules in this solution? Explain this difference based on the molecular structure of and electron distribution within these molecules,

Answer 1

In the solution mars percent of Etch in 40 ..In 1000 q. EHoH in 1000X90 - 400 gr 100 and Water - 11000- 00) = 600 gram Now density of pure EtCH ir 0.7850 glems. to volume of 400 gr ethanol, Ve- mers - 900 g density 0.7850 gſem = 509.55 Cm3 609.55 +601-80) cm density of pure water in 0.997o.glem . Volume of Goog lister_ 6oo n = 601.80 cm. oggro The critically, o ideally total volume 1509.55 +661-801 = 1111-38 cm But in this condition partictimelor returne density of the actual solution 0.9950 g1 com velusine of 1000 g solution & V = M160 900 d M = - as 150 g/cm3 = 1058.20 cm3 Assuming non-ideal condition the volume of lovo g. Solutim 1058.20 cm3 2 So, the ideal volume is greater than the non ideal volume of the solution. so, there occure to musit some association betereen the EtOH and ho molecule. And done to the associative intaroation the volume become ten than the actual &dume. And this areciation is due to the hydrogen bonding beth the Ethanol and the Water moleculen.

The Chr-CH2-OH molecular structure of ethomol and Water BH due to the righ electronegebrity of o atom, the it abaned to o are partially positive and the following association 1312-019, 8 HS+ Hst.... - CH₂ - C1t3 Het