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
Objectives: After doing this exercise you will be able to: 1 . Fill-up a F-22 form or write an application for obtaining the license permit for alcohol, 2 . Give justifica

Assume that we want to make buffer by dissolving in water some amount of the compound which we selected by the table as given below; After that adding either strong acid (f

Question : (i) What is meant by Integrated Coastal Zone Management? (ii) What is its main objective? (iii) List the principal measures involved in the implementatio

Which one of the following compound is ionic: (1) KCl                             (2) CH 4               (3) Diamond              (4) H 2 Ans: KCl

Two compartments each of 1m 3 capacity are connected by a valve and insulated from the surroundings and from each other. One compartment contains saturated steam at 683.6 kPa and

For the n= 2  energy level, how many orbitals of all kinds are possible: (1) 2        (2) 3        (3) 4        (4) 5 Ans: 4

An electron has principal quantum number 3. The number of its (i) sub-shells and (ii) orbitals would be respectively: (1) 3 and 5            (2) 3 and 7    (3) 3 and 9

Quantum numbers of an atom can be defined on the basis of: (1) Hund's rule (2) Aufbau's principle (3) Pauli's exclusion principle (4) Heisenberg's uncertainty principl

what the uses of NH4Cl,NH4OH and HCL,H2S in qualitative analysis?

which of the following has smallest heat of hydrogenation per mole A) 1-Butene                     B)trans-2-butene C)cis-2-butene                D)1,3-butadiene Ans)     D)1,3-