Chemical Engineering Interview Questions

the free electrons present in the last orbital of an element.

Valency is the number of free electrons present in an atom, ready to combine with other electrons in the orbit of an element. To get a more precise definition, please refer any physical chemistry books.

mass of water required to produce steam is less. steam economy is high

there is two term- evaporator capacity and economy?
capacity-no. of kg of water evaporated per hour.
economy-k.g. of water evaporated per k.g. of steam feed.
both of multiple evap.(if taken for all effect) is greater than single effect. i think question is ..

unit operation involves in physical changes only and unit process involves in both physical and chemical changes

Unit processes are hydrogenation, oxidation, nitration etc

Unit operations need to be performed in unit process like mixing, agitation, drying, quenching etc.,

the design of any distillation process involves in finding number of trays required for required separation,which is calculated by mc cabe method

Distillation column separates the liquid mixtures into their components. It has two sections the upper section is called rectifying section and lower one is called stripping section. The liquid having...

a=f/p,activity coefficient describes the deviation in ideal behavior of any liquid when it a non ideal mixtures ,which is dimensionless

I think activity means activity coefficient if it is that then it it is very easy to answer your question. Generally partial pressure term is used when there is mixture means more than one compund is ...

I dont think you can generalise this problem - at least not for flat plane and cylindrical co-ordinates. It really depends on how much bigger k2 is relative to k1 and how big the pipe thickness is relative to the diameter.

I do have a question here, If the material of lower insulation be bounded to the first system, doesn't that result in heat loss?

By using metal catalyst and using proper temperature and pressure

One way of increasing the Productivity / yield is to minimize the side reactions, minimizing the byproducts. This can be done by selecting proper process / catalyst if used in the process.

The vapor liquid equilibrium can be determined by their relative volatility and the X-Y values and with these values we make a graph curve on between these two values the vapor liquid equilibrium is achieved.

Correction of Bernoulli equation for fluid friction

The process which involves chemical reaction is called unit process like chemical reactions, chemisorption, nitration, where as the process which involves only physical change is called as unit operation like distillation, physical adsorption etc.

Scale up the product as per our plant capacity, check for utility requirement, check for availability of equipments, PFD, P&ID preparation, hazard study

Fluid having high specific volume must go through the shell side.High temperature and pressure stream must go to the tube side and more viscous fluid must go to the shell side.so,that the baffles impart turbulence to the viscous fluid.

Fluid having more corrosive nature and higher fouling factor is passed through tube side because we can easily replace the tube after maintenance but if the shell get corroded it will be more economical to replace or maintain it.

if the difference between boiling points is less than 25 degrees we use fractional distillation otherwise we use distillation

Fractionation is used when the boiling point difference is less than 70 degree, but distillation is widely used not need this requirement..both are distillation or we can say processes of separation based on boiling point.

in case of azeotrope only alternative is through azeotropic distillation ... extractive distillation s used when relative volatility is close to 1 and no of tray reqd r high

b.p of water is 100C b.p of toluene is 110C , they will form azetropes , so i would go for azetropic distillation or maybe extraction

If 2 systems A & B are in equilibrium with one another , and if B and C are in equilibrium , then it can be concluded A and C are also in equilibrium with one another

Absolute entropy of a perfectly crystalline solid at absolute zero temperature is zero.

The Wilson equation was published by Grant M. Wilson as Vapor-Liquid Equilibrium. XI. A New Expression for the Excess Free Energy of Mixing

Wilson plot /equation is the graphical calculation of convective heat transfer coefficient is proportional to Uexp 0.8.

Software's or u can say simulators are used mainly to get simulated results of many parameters like product composition, pressure, temperature, mole-mass fraction etc. this results will most probable ...