Negative deviation or positive deviation, Chemistry

Refer to diagram A, which describes the system formed by water-ethanol mixtures at 1 atm pressure, but is not drawn to scale.  Industrial ethanol production results in the lowest-boiling water-ethanol mixture.  This lowest-boiling mixture is normally about 95.7 % ethanol.  Its boiling point is about 78.2 ºC, whereas pure ethanol boils at 78.5 ºC.

1105_Negative deviation or positive deviation.png

Diagram A

(a) Carefully detach the copy of the diagram from the back of this paper and attach it to your answer book.  Enter on the diagram any value marked by a question mark "?" (there are six of them).

(b) Name the mixture which consists about 95.7 % ethanol, 4.3 % water.  Is the ethanol-water system one displaying 'negative deviation' or 'positive deviation'?

(c) Normally, in the industrial process, a "wash" (a dilute solution of ethanol, represented by point a on diagram A), is distilled using an efficient fractionating column.  Assuming a fractionating column operates as a system of repeated distillations, describe how a product of 95.7 % ethanol composition can be achieved.  Enter letter symbols on your diagram to refer to, starting from point a.  Would the 95.7 % ethanol solution be recovered at the top of the column, or from the flask?

(d) It is often wrongly assumed that 95.7 % is the greatest concentration of ethanol attainable industrially, starting from a "wash".  However, in practice, the 95.7 % solution can further be dehydrated using vigorous dehydrating agents (such as CaO) to give a solution approximately 97% ethanol (marked by h on the diagram).  Show how, if a sufficient amount of  97% solution was to be poured into a flask topped by an efficient fractionating column, further fractional distillation might give amounts of highly pure ethanol.  At the end of this process, would the ethanol be in the flask, or recovered at the top of the column?  What would be the other product of this process?  Use and amend the supplied diagram as necessary to help explain your answer.

(e)  Using the 'Phase Rule', calculate the absolute degrees of freedom for the systems denoted by the four points p, q, r and s.

Posted Date: 2/25/2013 1:24:59 AM | Location : United States







Related Discussions:- Negative deviation or positive deviation, Assignment Help, Ask Question on Negative deviation or positive deviation, Get Answer, Expert's Help, Negative deviation or positive deviation Discussions

Write discussion on Negative deviation or positive deviation
Your posts are moderated
Related Questions
Write down the complete names and the commonly used abbreviations of the molecules A and B. a) Illustrate the line bond structures of the reactive moieties of these molecules i

#question.factors affecting thermogravimetric curves.

I''m trying to find articles and books online that I can get information on the mechanism of the Darzen''s reaction. Any ideas?

Ethelene+diaminotetraacetate---->1,4- diaminobutane from ethylene CH 2 =CH 2 +EDTA---->NH 2 -CH 2 -CH 2 -CH 2 -CH 2 -NH 2

You may have eaten "astronaut ice cream" as a kid at a science museum or planetarium to experience the type of food eaten by astronauts. Astronaut ice cream is made by chilling the

The two chair conformations of cis-1,3-dimethylcyclohexane

How many fluorescence photons will really be detected on average by the photo detector during a 10 ms acquisition window if one diIC12 molecule is located in the illuminated area?

why firstly test for ammonium radicals before analysis of cation radicals

The formation Alkenes by the dehydration of alcohols (using concentrated H 2 SO 4 ) the hydrogen atom will be separate (to remove as water) from the adjacent carbon atom correlated

Properties of Detergents - Oils and Fats Detergents are superior cleansing agents due to following properties. (i) These can be employed both in soft and hard waters as the