Tuesday, April 24, 2012

Viva voce #1

Hello! Here I go with my practical experience :) I'm doing my university practical examination this week. Completed 2 out of 4 practicals :) My mood got spoiled in my lab because of the moody chart!
 But, successfully, did the viva voce  good for the 2 exams :) I shared some of my viva voce questions with answers as it might help someone searching for some answers (as I do every time, the day before exam)

Chemical Engineering laboratory:
I was given with a question :

" Draw Moody chart for fluid flow through non circular pipe" with some specifications of pipe diameter.

I got shocked, as I don't know what's a Moody chart! :( :( Non circular pipe?!!! Still again a great confusion!

But, I managed to guess what was that non circular pipe! It is nothing but, "Annulus". We use to say " Fluid flow through annulus" , so, I got little confused with the twisted question! Then, the moody chart.. I didn't bother about that. I did the experiment, drawn graph between friction factor and reynolds number as we did in our previous lab classes. But, to my goodness, I was right, Moody chart is nothing but, the plot between Friction factor and reynolds number! :D :D With out knowing that, I did it right! :D :P

 External Examiner :  What's the application of flow meters in biotechnology industry?
Me: For knowing and adjusting the behavior of nutrient broths or other solutions while they are transported via pipes.

 External Examiner: Which heat ex-changer type is efficient and why?
Me: Counter flow - as the temperature difference is maintained, efficient heat exchange takes place. whereas in parallel flow, the temperature difference gets reduced as the fluid reaches the end of the pipe, hence there will be no efficient heat transfer. ( Temperature difference is the main criteria for heat exchange )

 External Examiner: In fluidised bed, when porosity increases, what happens to pressure drop? 
Me: Pressure drop decreases. When there is more space for the fluid to flow freely, there will be no hinderance for the fluid flow, hence, there will be no drop in pressure. ( I thought for a minute and reasoned like this, I don't know whether I was right :P )

 External Examiner: Application of heat exchanger in biotechnology?
Me: Sterilisation and cooling during fermentation.

 External Examiner: Partition coefficient in liquid-liquid extraction? Discharge coefficient? 
Me:  Partition coefficent is ratio between amount of solute in extract to amount of solute in raffinate.
Discharge coefficient in head flow meters is the ratio between experimental discharge to theoretical discharge.

Hoping to get good grade - the highest "s" grade - above 90% :) :D :)

Instrumental Methods of Analysis: 

Question I got,

Major experiment: Estimation of sulphate concentation.
Minor experiment: Determination of pKa value of p- nitrophenol.

I enjoyed doing this, as we took the readings for the standard of sulphate estimation in groups :D :) Only for the unknowns we took the readings individually :)
pKa value determination is very simple using titrations and pH meter :) Got pKa value as 9.3 for
p-nitrophenol ( the exact value we gor during our previous lab classes )  Viva voce was also simple :) as follows :

 External Examiner: What's the principle behind this sulphate estimation?

Me: Based on the turbidity developed, readings are taken in terms of NTU for standard as well as unknown. By plotting graph, we could determine the concentration of unknown.

 External Examiner: Why nephlometer for this estimation why not spectrophotometer? 
Me: Spectrophotometer is generally preferred for non -turbid solutions. Nephlometer is specifically used for turbid solutions. Hence, we use nephlometer.

External Examiner: significance of pKa? 
Me: At the pKa, the compound will be more stable. to be short, pH at which the compound remains stable or the compound has more stability.

 External Examiner: What kind of components could be separated using TLC? 
Me: Colored pigments, oils and components with variation in molecular weight.

 External Examiner: Colored pigments could be examined easily after separation, but, how you will examine the separation of oils? they are not colored? 
Me: Using Visualizing agents like iodine vapor.

 External Examiner: Other possible methods for visualizing? 
Me: I don't know sir, (but, now I found one another method) If the sample contains any chromophore substance, it could be identified by visualizing under UV rays for sometime. It will develop color.

Successfully completed my 2 lab exams with good satisfaction. Hoping for "s" in both labs :) :D :P

Note: I don't know whether the above answers are right, but, I always believe that I would be right for at least 80 % .  :) :) (Confidence boss.. confidence.. :P ) If your reading this for your educational purpose, just cross check my answers. I might go wrong at times.
Have a good time :)