Interview Questions.

Top 100+ Chemical Interview Questions And Answers

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Top 100+ Chemical Interview Questions And Answers

Question 1. For A Given Bulk Solid How Can The Particle Size Distribution Be Determined?

Answer :

In order to decide the particle size distribution the simplest method is to utilize a sieve stack. In this technique a stack is created of with unique mesh sizes at each stack stage. The structure is such that the biggest mesh size is at the top and the smallest at the bottom. Once this setup is created the before starting the weight and other values of the stable is cited down. Once this is finished the solid is located at the topmost cylinder and the complete setup is uncovered to a combination of vertical and horizontal actions. This will make the strong pass through different mesh sizes within the system setting apart the special particles in keeping with their sizes. There are different more superior strategies of figuring out the particle size distribution as well such as video imaging and laser diffraction as nicely.

Question 2. What Are The Different Characteristics That Can Affect The Flow Of Bulk Solids And How?

Answer :

The important characteristics which could affect the go with the flow of bulk solids are as follows:

Moisture Content: while the moisture content is excessive the majority solids end up sticky in nature. This moisture can every now and then be absorbed from the environment by means of a few solids.
Temperature: The float of the majority solids may be every so often suffering from the temperature and additionally the duration for which it's miles uncovered to a specific temperature.
Particle length: More cohesive debris are normally found in bulk solids which can be finer. Round debris are dealt with without problems in evaluation to odd, asymmetrical shapes.
Time at rest: Many times the go with the flow of sure bulk solids is suffering from the time for which it's been kept stagnant or at rest. The extra it is saved at relaxation the extra sluggish the majority strong flows.
Analytical Chemistry Interview Questions
Question three. What Do You Understand By Wet Bulb Globe Temperature?

Answer :

The wet bulb globe temperature index is used to measure the sultriness of the environment. The sultriness is calculated on the idea of the humidity impacts, the air pace and temperature and also the sun`s radiant heating aspect. The sultriness in some instances might be fatal and hence it is very essential to preserve this beneath attention. The wet bulb globe temperature index variety became advanced within the 1950`s and is now established as an enterprise fashionable. It is constructed from 3 temperature readings:

Wet bulb temperature
Ordinary dry bulb temperature
Black bulb globe temperature
Question 4. In Case Of Welded Vessels Why Is Stress Relieving In The Form Of Post-weld Treatment Necessary?

Answer :

When a metallic is welded collectively the point at which the two surfaces are joined are subjected to very excessive temperatures. During this time period the metals can undergo a variety of random metallurgical tactics. This causes the steel to be tougher and brittle. This relies upon on the quantity of carbon content material. In order to alleviate the steel of these properties warmth remedy is done on the affected regions. By doing so the affected areas ductility increases. In this process the heat is maintained inside the affected metallic in line with the thickness of the metallic. The temperature of the heat is calculated from the P variety which is specific for a specific composition.

Question 5. What Significance The Angle Of Repose Holds In The Chemical Industry, Explain?

Answer :

The attitude of repose is a assets of particulate solids. A conical pile is fashioned while a bulk strong is poured onto a flat floor. The attitude formed between the flat surface and the pile part is called the angle of repose. The attitude of repose relies upon on the subsequent factors:

Density of the cloth
Surface area
Coefficient of friction of the cloth
A fabric having a low perspective of repose might constantly create waft piles in comparison to materials with a high perspective of repose. This is used inside the designing of equipments which can be used for particulate solids. In addition to that this attitude may be used to calculate the size of the conveyor belt this is used to transfer the materials.

Chemical Engineering Interview Questions
Question 6. What Are The Design Considerations For A Piping System For The Transfer Of Slurries?

Answer :

The following points ought to be considered for designing a piping device to carry slurries:

The design of the piping device ought to be capable of self drain.
At the sections of the pipe in which self draining isn't possible provision to install manual draining should be established.
At sure factors where the possibilities of plugging are excessive, rod-out or blow-out connections have to be provided to clean the lines.
In order to make flushing viable smooth-out connections have to be hooked up on either facet of the primary valves.
For clean get admission to all the manifolds should have flanged connections.
T-connections are a must for get entry to flanges.
Question 7. What Are The Problems That Are Associated With The Expansion Joints?

Answer :

Expansion joints are stated to be susceptible factors that are used in piping. They are used to lessen the pressure that comes inside the piping at the same time as putting in and enforcing it. This allows minor piping to be settled at some point of the becoming a member of feature. Expansion joints can’t stand the strain that is being produced through the piping forces.

The issues that have been given are as follows:

Expansion joints get grimy very without problems and they have a tendency to accumulate because the time progresses.
They encompass some vulnerable points which can`t stand the pressure of the piping.
The issues can be removed if the drains are set up well and purging of the fabric is being achieved.
Drawing and Painting Interview Questions
Question eight. What Is The Method Involved In Analyzing Powders For Composition?

Answer :

The technique that is used to research powders for compositions known as as Fourier rework-infrared spectroscopy. This technique is broadly used to send the mild beams of various wavelength passing through the pattern this is given and the mild this is meditated from there will be analyzed by means of spectroscopy. This technique is used to find out the absorption of each wavelength. The wavelength is measured with the laser light this is being referenced and on the idea of that calculations could be completed. The technique is followed to measure the compositions with accuracy.

Question nine. What Are The Methods Involved To Test Helium Leak Testing In A Vacuum System?

Answer :

The helium receives detected while it is found in the region of suction line. The helium supply is exceeded over the flanges and feasible assets of leakage inside the vacuum system. The tracking of the machine takes vicinity to see the detector and the pump suction to be observed for the detectable amount of helium. The strain can be multiplied or decreased in keeping with the surroundings. If the device is permitting the pressure and the vacuum on the same time then extra strain may be carried out to set the leaks. An set up of IR unit may be finished to suction the substance of the pump and the spraying might be finished at the flanges.

Organic Chemistry Interview Questions
Question 10. What Are The Criteria's Involved In Choosing Mass Balances For Components?

Answer :

The mass balances are used to mix all the hundreds which might be gift in the substance and create an standard effect while it's miles combined with other factors. The equations can be set for the element to permit any of the components utilized in mass balances.

The criterions on which the balances are established are as follows:

Need to find out which thing(s) are concerned in solving the equations, with out right records the equation can`t be solved.
Find out approximately the additives approximately which the reasonable assumptions can be made. By doing this the process gets simplified and it's going to help in making quick calculations.
Question 11. What Are The Assumptions Made On Conservation Equation?

Answer :

The conservation equation is carried out to the property of the gadget. It may have complex as well as clean to remedy calculations:

Closed machine: that does not have flows out of the substance. It offers with the closed mass go with the flow. The equation to calculate that is: Accumulation= Generation
Open system: that lets in the substance to enter or go away the device.
Conserved state gadget: in which no technology of the portions takes place. The portions in this does not get created or destroyed. These portions are beneficial to stability in keeping with the users want.
Steady State gadget: wherein no accumulation of the substance is in regular kingdom. This gadget avoids having differential equations. The system desires to be established before it may run in any state.
Chemistry Interview Questions
Question 12. What Is The Procedure To Estimate The Friction Factor Involved In Heat Exchanger Tubes?

Answer :

The following system is involved in determining the elements used within the heat exchanger tubes which are varying with the temperatures.

These are as follows:

Determine the common of the temperature by taking the suggest of all the temperatures stored within the processing line.
Check the circumstance of the fluid getting into the road at round three hundred Celsius and leaving at round 280 Celsius.
Determine the physical houses at the temperature of 290 Celsius and the friction factors of the tubes at the same temperature.
Use the method to calculate the friction factor of the laminar float within the case in which the liquid is cooling: Mean temperature / ((sum of viscosity / wall viscosity)*0.38) Where Bulk and wall is determined at mean temperature over the duration of line. Use the components to calculate the friction factor of the turbulent float in the case where the liquid is cooling:
(Mean temperature + bulk homes / ((sum of viscosity/wall viscosity)*0.11))/(bulk viscosity/wall viscosity)*0.17
Analytical Chemistry Interview Questions
Question thirteen. What Is The Use Of Gear Pumps In Motor?

Answer :

Gear pumps uses meshing gears that allow the pump fluid to be displaced by the method of displacement. They are used for hydraulic fluid power programs. They are one of the key factors involved in chemical installation having a positive viscosity to pump fluid. This form of pumps makes use of fine displacement pump having excessive stress and low capacities. This includes the ability to deal with extensive range of viscosities, and permit smooth to build and maintain the pumps. The gear pumps are controlled via the motor velocity. Gear pumps can’t cope with excessive tolerances and the fluids which can be freed from abrasives.

Question 14. What Are The Factors Involved In Considering The Choice Of Dry Screw Compressor?

Answer :

Screw compressors are made up of a pair of meshing helical screws that is used to compress the gases. The dry screw compressors are used to have a float range of 85-a hundred and seventy m/h and the release strain is of 2070-2760 kPa. The dry screw compressor includes timing gears that is maintained aligned with the rotors. The effectiveness is depending on the clearances that exist between the helical rotors and between the chambers used for sealing the compression cavities. They are compact and easy having the restrained vibration and require spring suspension as well.

Question 15. What Is The Process Of Including Heat Exchangers In Ammonia Refrigeration System?

Answer :

The warmness exchangers are used in ammonia refrigeration device from a very long time. The warmth exchanger used is having smaller sizes and they are equal to the tubular exchanger can. This procedure works high-quality for flooded machine that require a separate liquid from the vapor. The machine that is explained consists of a vessel, a drum, and accumulator and header tank with the heat exchanger. It works like this:

Liquid ammonia movements from vessel to exchanger
Vapor is back to center of drum
Vapor is removed from the drum and liquid enters through exchanger because it has lower density than others coming into on the equal fee in the gadget
Chemical reaction Interview Questions
Question sixteen. What Is The Method Adopted To Minimize Shell Side Pressure Drop In A Shell?

Answer :

The method of protecting the shell from the pressure drop is very critical as it is very critical level, where if not taken care properly the shell has to get replaced due to its degradation. In this rods or tube protectors are used in preference to plates in pinnacle rows. The use of these rods puts much less stress drop and provides higher distribution of the pressure at the plate. The plate that is used causes an abrupt of ninety diploma turn of shell flow and an additional strain drop at the whole shell. Use of the tube protectors will permit the shell to be stored from this and continues its toughness.

Question 17. What Are The Strategies Acquired To Cure Tube Vibration And Exchangers In A Shell?

Answer :

The strategies that can be followed are as follows:

To cure the tube vibration uses the tubes that doesn’t permit passing of the waft-precipitated vibrations via them and are longer in top than others. Usually the tubes supported
Are of three-four inch. To make the package deal stiff insert metal slats and rods among the tubes that is used in the process.
Add a shell nozzle contrary of the inlet to cut the glide of the velocity of the fluid in 1/2. This answer works for non-detachable bundles which could without difficulty be solved also by way of adding a distributor belt at the shell. This might be high-priced strategy to adopt as it requires greater guy strength and use of extra tubes.
Painter Interview Questions
Question 18. What Are The Factors Involved In Designing Kettle Type Reboiler?

Answer :

To design the kettle type reboiler the requirements that had to be present are as follows:

The length of the kettle must be determined.
Provide the gap to gradual down the vapor velocity of all the liquid droplets.
Deciding the destination where the vapor would be deposited.
Handling a distillation tower with the following property: huge area, excessive efficiency and high reflux fee.
The top of the vapor area must be kept such that the variations inside the temperature gained’t have an effect on the kettle. There ought to be high heat flux for the kettles that run on higher temperatures.
Chemical Engineering Interview Questions
Question 19. What Are The Steps Taken To Operate A Tank-blanketing Valve?

Answer :

The steps taken are as follows:

Tank blanketing valves offer a way to save you and manipulate the fires within the flammable liquid garage tanks.
The vapors which can be produced cannot be ignited if there's no supply of oxygen gift at that time.
The oxygen in most of the instances being supplied by way of the air this is drawn into tank from the surroundings whilst the empty procedure is taking location.
Install tank blanketing valves with inlet linked to the inert fuel this is kept underneath the stress. And the tanks outlet is being placed in vapor space.
The strain drop is happening in the tank at predetermined level in which the blanketing valve allows the transfer of gasoline into vapor space.
Question 20. What Are The Steps Required To Design A Vapor-liquid Separator Or Flash Drum?

Answer :

The steps which can be required are as follows:

The length of the vapor-liquid separator relies upon on the drift rate of vapor and the liquid that is popping out of the vessel.
Assumed from the flow costs that if they're recognised then the size may be discovered out.
Use vertical pressure vessel to set it up or installation it at given vicinity.
The period to diameter ratio will be taken to provide liquid stock among the level of liquid and the bottom of the vessel.
Provide a blockage mesh segment on the vapor outlet to permit the vapor skip via the mesh this is taken and may efficaciously depart the vessel.
Let liquid waft control the extent of the valve.
Question 21. Why Does Catalytic Converter Used In An Automobile?

Answer :

The catalytic converter is a tool that converts dangerous compounds in harmless compounds. The compounds harmful in nature are as follows:

Hydrocarbons- this is within the form of unburned fuel that creates pollutants and is extra dangerous.
Carbon monoxide may be very dangerous gas fashioned by means of the combustion of fuel and used specifically for fuels.
Nitrogen oxides is likewise one of the gases that is toxic in nature and produced via the discharge of warmth from the engines. The release of nitrogen from the engine receives mixed with the oxygen within the air.
The catalyst converter takes these dangerous gases and makes use of the catalyst this is covered on the ceramic honeycomb or beads and attached to the exhaust pipe. This converts the carbon monoxide in carbon dioxide and makes it smooth for the nature to consume it. The hydrocarbon receives transformed in carbon dioxide and water. Same manner the nitrogen oxides additionally receives converted in nitrogen and oxygen.

Question 22. What Are The Different Ways In Which Solids Can Be Blended?

Answer :

There are diverse methods wherein solids may be blended, some of the not unusual techniques are:

Convective blending: In this type of mixing the organization of particles of a strong is transferred from one place to some other, lively repositioning takes place in this method. This sort of mixing is typical within the Trough mixer.
Diffusion blending: In this form of mixing a new interface is fashioned over which the particles of a stable are disbursed. A accurate example of diffusion mixing is inside the conventional barrel mixer, where a new interface is fashioned.
Shear Mixing: In this form of mixing slipping planes are created over which the institution of debris of a solid are blended.
Question 23. What Are The Different Types Of Equipments For The Conveyance Of Solids?

Answer :

The various kinds of equipments to be had for the conveyance of solids are as follows:

Gravity Chutes: This system is based on gravity for the solids to fall under.
Air Slides: In this device the debris are suspended in air, and float at an attitude to the horizontal.
Belt Conveyors: This equipments use a belt to transfer the solids.
Screw Conveyors: The solids are moved using a rotating helical impeller.
Bucket elevators: The solids are moved the use of buckets that are connected to a belt in movement.
Vibrating Conveyors: The stable particles are subjected to vibrations and tour over to a table in a series of steps.
Pneumatic/ Hydraulic Installations: The debris are transported over a movement of air or water.
Question 24. What Are The Reasons Of Removal Of Particles From Effluent Gas?

Answer :

The essential motives for the removal of debris from effluent gasoline are:

In order to defend and maintain the health of the employees and operators in the plant. It is also achieved to shield the encircling population. The number one danger is because of the inhaling of the dirt debris which could purpose fitness issues.
It is likewise accomplished to reduce the chances of explosions. Many carbonaceous substances stay suspended in air and whilst mixed with finely powdered metals can shape a surprisingly flamable aggregate.
Particles are also removed to lessen the lack of treasured substances.
It also can be used to recycle the gasoline for ex in case of blast furnaces the gas is used to hearth the stoves.
Drawing and Painting Interview Questions
Question 25. In A Crusher Where Is The Energy Provided To It Is Used Up For?

Answer :

The electricity fed to a crusher is utilized for the following purposes:

To produce the elastic deformation of the debris previous to the fracture of the particles.
In order to supply inelastic deformation this reasons the particles to reduce in length.
The power is also used to motive the equipments elastic distortion.
In the friction of the particles between themselves and among the gadget.
The strength additionally gets used up in the shape of warmth, noise and vibration inside the plant.
The power additionally get used up inside the friction losses within the plant. Most of the power is lost and just a few of it is properly utilized. Nowadays it's miles of top importance to lessen the power losses.
Question 26. On What Basis Are Materials To Be Crushed Evaluated Apart From Size?

Answer :

The preference of the crusher system to be hired to overwhelm the materials relies upon on the subsequent houses aside from the dimensions of it:

Hardness: The hardness influences the electricity intake and the carrying of the device. With hard substances it's miles important to apply a low velocity system along with pressure lubrication.
Structure: Normal granular materials can be crushed by the usage of compression and impact methods. On the opposite hand for fiber like substances compression and effect strategies do not paintings alternatively a tearing motion is required.
Moisture content: The moisture content inside the substances can greatly have an effect on the choice of machines. In case of excess moisture the substances go with the flow gets hindered and it's miles crucial to save you them from caking together and shape balls.
Crushing Strength: The amount of power this is required to crush a material may be derived without delay from the crushing strength of the fabric.
Friability: This belongings shows the tendency of a cloth to fracture.
Stickiness: As the name shows this assets is used to evaluate how sticky a material is as a completely high sticky material can clog the equipment.
Question 27. What Are The Advantages Of Using A Ball Mill Over Other Conventional Methods Of Crushing?

Answer :

The blessings of the usage of a ball mill over different conventional methods are as follows:

The mill can be used in more than one modes. It may be used in both moist and dry modes. The wet mode helps within the removal of the product.
The set up value and the power consumption of the mill is low.
Since the mill may be used in an inert ecosystem hence it could be used for the crushing of explosive substances.
It may be used for any kind of hardness substances and additionally the grinding medium is reasonably-priced.
It can also be used for continuous and batch operations.
The ball mill supports two forms of grinding:
Open circuit grinding > Closed circuit grinding
Organic Chemistry Interview Questions
Question 28. Mention Some Of The Specialized Grinding And Crushing Methods?

Answer :

Some of the in particular developed grinding and crushing methods are as follows:

Electrohydraulic crushing: In this method an underwater discharge is made from a high capacity capacitor.
Ultrasonic Grinding: This form of grinding the material identification positioned among a force roll and plate both of that are ultrasonically activated. This method is used for grinding micro sized materials.
Cryogenic grinding: For sure substances powerful grinding isn't possible through conventional way inclusive of rubber, textiles etc. In order to deal with this trouble the material is frozen to ultra low temperatures the use of liquid nitrogen. Once the material is frozen it is grounded as in line with requirements.
Explosive Shattering: This sort of shattering continues to be on experimental foundation, it entails electricity to be transmitted to the debris inside the shape of shockwaves from an explosion chamber.
Question 29. What Are The Assumptions Made For Kynch Theory?

Answer :

The following assumptions are made for the Kynch Theory:

Across the horizontal layer the particle concentration is uniform
The effects of the wall may be omitted.
No differential settings of particles are taken into consideration because of form, length or composition adjustments or differences.
The speed at which particles fall relies upon most effective on the local attention of the particles and not anything else.
The attention is considered to be uniform at some stage in or it can be assumed to growth towards the bottom.
The velocity of sedimentation strategies zero because the attention reaches the limiting fee. This limiting cost corresponds to the sediment layer at the bottom which gets deposited.
Question 30. What Are The Merits Of Using A Falling Film Evaporator?

Answer :

The benefits of using falling film evaporators are as follows:

These kinds of evaporators have very high warmness switch coefficients starting from 2000-5000 W/m(rectangular) for water and 500 to one thousand for natural liquids
The house instances are brief in case of heated surfaces, five-10 seconds without recirculation
They have very low stress drops, zero.2-zero.Five kN/m(square) ,
These evaporators are nicely proper for vacuum operations as properly.
The evaporation ratios are very excessive. 70 in step with cent with out and ninety five in line with cent with recirculation,
They have a totally extensive running variety, they could provide as tons as 400% of the minimal throughput,
In addition to the above advantages they have got a low price of operation and are less liable to fouling
Question 31. What Is The Most Common Cause Of Solid Size Segregation In Bulk Solid Systems?

Answer :

Many engineers generally point at once to the pneumatic conveying device as a source of such a hassle. The fact is that in maximum instances, segregation occurs because of the differences in sizes of the articles. As a rule-of-thumb, if the scale ratio extends outdoor of around 1:1.Three, then there will maximum probably be segregation. This being stated, one should look at the system responsible for determining the particle size instead of thepneumatic conveying device if this hassle is happening. Reference: Richard Farnish, the Wolfson Centre for Bulk Solids Handling Technology

Question 32. How Can One Determine The Particle Size Distribution For A Given Bulk Solid?

Answer :

While there are high-tech techniques of appearing such an evaluation (laser-diffraction and video imaging gadget are to be had), the best way is to use a sieve stack. For instance, to research a selected strong, one might stack numerous extraordinary mesh sizes into a cylinder with the largest mesh establishing at the top and development down through the cylinder to finer mesh. The cylinder might include a pan on the bottom. Before beginning, weight the test pattern, every piece of mesh, and the pan. Then, the pattern is loaded into the pinnacle of the take a look at cylinder and the cylinder is uncovered to a aggregate of moves (shaken) to permit the solids to bypass through the proper mesh sizes.

Question 33. What Is A "saltation Velocity" And How Is It Used In Designing Pneumatic Conveying Systems?

Answer :

The saltation pace is described because the actual gas speed (in a horizontal pipe run) at which the particles of a homogeneous strong waft will begin to fall out of the gas stream.

In designing, the saltation pace is used as a basis for selecting the design gas speed in a pneumatic conveying gadget. Usually, the saltation fuel pace is extended by way of a element, which is depending on the character of the solids, to reach at a layout gas pace.

For instance, the saltation speed element for nice debris can be about 2.Five while the component can be as high as 5 for course debris along with soybeans could.

Chemistry Interview Questions
Question 34. What Are Some Characteristics Of Bulk Solids That Can Affect Their Ability To Flow Properly?

Answer :

Four essential elements to recall include moisture content material, temperature, particle size(and form), and time at rest.

An growth in moisture content will commonly make solids more "sticky". Some solids will take in moisture from the air, that's why nitrogen is often used as a provider fuel (among other motives).
For a few solids, their capability to drift can be adversely impacted by using temperature or maybe the duration of time that the debris are uncovered to a selected temperature. For example, soybean meal flows well at ninety °F however start to shape massive bridges at a hundred °F.
Generally, the finer a bulk solid will become, the extra cohesive the debris. Round debris are usually easier to handle than "stringy" or oddly fashioned particles. As debris relaxation in a bin, they could compact together from their personal weight. This can create sturdy bonds between the debris.
Often instances, re-initiating drift can spoil those bonds and the solids will drift as regular, but this may depend on the load at given places within the bin.
Question 35. After Conducting An Internet Search For Ways To Reduce Energy Costs, I Found A Recipe For Whitewashing That Is Said To Reflect Sunlight. The Recipe Calls For 20 Pounds Hydrated Lime To 5 Gallons Water To 1-quart Polyvinyl Acetate. What Is A Good Source Of Polyvinyl Acetate That I Can Buy At A Local Store?

Answer :

Well your recipe sounds exciting. Finding your polyvinyl acetate must be easy. Go for your nearest branch store and pick up a large field of plain white glue! The leader energetic element in this glue is polyvinyl acetate. Good luck with your venture!

We wanted to know a way to impart various hues to copper cord by means of simply dipping them into numerous chemical substances, formulations, and so on. This copper cord is to be utilized by us for our hobby of creating diverse art objects from copper wire.

Changing the coloration of copper by way of chemical reactions is a risky Endeavour that I simply do no longer propose. However, there may be some thing you could do to get a inexperienced color, if truth in case you are familiar with the Statue of Liberty right here in America, this would explain why it's miles inexperienced. You see, the out of doors of the statue is covered with copper and being in New York City, it's far subjected to acid rain. This reasons the formation of some other chemical that coats the copper and gives the statue its green color. The two acids that you can use are nitric acid (which fits first-class) or sulfuric acid (so that you can probable require a few gentle heating in conjunction with the acid). I am no longer certain if there have been an amazing manner to get nitric acid out of something you could have around the house, you will probable have to buy it.

Sulfuric acid may be obtained from vehicle batteries (the liquid internal). You will need to boil the mixture (to concentrate it through evaporating the water), until you spot white fumes (which are very risky). Then positioned your copper is while the acid is warm and depart it there until you get the colour you would love. If you are going to do that, please do it outdoor or in a nicely ventilated vicinity and make certain you've got a few baking soda on hand is case you get a number of the acid on your pores and skin. If you're looking for a unique colour or more colours...I advocate contacting someone who manufactures copper or a person who specializes in it. Please be very careful in case you do any of the experiments that we've suggested. The green color which you get will now not be an inventive vivid green, but an unattractive darkish, milky inexperienced. You may ought to recollect making your artwork out of some thing that may be a bit less difficult to coloration. Good good fortune along with your project!

Question 36. What Is An Effective Means Of Removing Silicone From Aluminum?

Answer :

Silicon is widely recognized for its chemical inertness, (i.E. It has a tendency no longer to react with many different chemicals). Depending on what sort of silicon you're dealing with, this could or may not be clean to solve. If the silicon is from a lubricant, it is probably the graphitic form, which is soluble in a sturdy combination of nitric, and hydrofluoric acids, neither of which I might suggest in order to use...Nor hydrofluoric acid is not easy to return via. If it's far silicon from an acidic shape (possibly every other shape other than a lubricant), you should try ammonia. In either case, leave your acetone at domestic...It'll NEVER paintings! UPDATE: An ammonia solution worked very well in this situation

Chemical response Interview Questions
Question 37. What Does The Catalytic Converter On An Automobile Really Do?

Answer :

A catalytic converter is a device that makes use of a catalyst to transform three harmful compounds in vehicle exhaust gasoline into harmless compounds. The 3 dangerous compounds are:

Hydrocarbons (within the form of unburned gasoline)
Carbon monoxide (shaped by the combustion of gas)
Nitrogen oxides (created when the warmth inside the engine forces nitrogen in the air to mix with oxygen).
Carbon monoxide is a poison for any air-respiratory animal. Nitrogen oxides cause smog and acid rain, and hydrocarbons produce smog. In a catalytic converter, the catalyst (in the form of platinum and palladium) is lined onto a ceramic honeycomb or ceramic beads which can be housed in a muffler-like bundle connected to the exhaust pipe. The catalyst allows to transform carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It additionally converts the nitrogen oxides back into nitrogen and oxygen.

Question 38. What Compounds Are Responsible For The Odors That Come From Wastewater Treatment Plants?

Answer :

Compounds consisting of hydrogen sulfide, methyl mercaptan, dimethyl sulfide, and dimethyl disulfide can all contribute to this foul odor.

Question 39. What Is The Average Salary For Chemical Engineers?

Answer :

AIChE just got here out with the results of a ChE profits survey (See Chemical Engineering Progress, September 2000). To solution your query depends on years of provider, the type of diploma, the dimensions of the corporation and the kind of enterprise, i.E. Engineering, Design & Construction (E&C), Plant work, Self Employed as examples. To summarize in brief, median beginning revenue is ready $50,000 consistent with year. Median revenue amongst all Chemical Engineers is ready $77,200 and annual increases are averaging 4.4%. As a ways as activity potentialities that again relies upon wherein place you are interested. In preferred, jobs are nevertheless searching right. However, be forewarned, Chemical Engineers now not command the job protection that we as soon as had. In monetary downturns, it is able to get nasty.

Question forty. Who Built The First Production Scale Pla (polylactic Acid) Facility?

Answer :

The first manufacturing scale PLA (polylactic acid) facility become constructed with the aid of Cargill Dow in The Blair, Nebraska, and USA. The facility is designed to consume 40,000 bushels of corn in line with day and bring 300 million lb/year of PLA.

Painter Interview Questions
Question forty one. What Is The Largest Application For Surfactants?

Answer :

About 60% of overall surfactant marketplace is composed of the detergent and cleaning merchandise market. These varieties of compounds are offered in large volumes at low fees.

Question forty two. How Can You Separate Hydrogen Peroxide Into Hydrogen And Oxygen?

Answer :

This is effortlessly done. Just expose hydrogen peroxide to air. The oxygen within the air will oxidize the hydrogen peroxide into its factor gases. It occurs far too slowly for commercial or most different functions (an enzyme catalyst can be used to speed up the system). However, neither hydrogen nor oxygen is produced in this way in industry. The enzyme catalyst is known as "catalase".

Question 43. What Is The Easiest Way To Extract Hydrogen From Water And The Safest Way To Store It?

Answer :

Electrolysis (which means splitting the use of strength) of water is the approach for generating hydrogen from water. The most secure way to commercially keep it'd be to apply a palladium "sponge", because palladium adsorbs several hundred times it's personal volume in hydrogen. One would need to supply a compound with a very high surface vicinity, which has a skinny coating of palladium. This sort of material is commonly used as a catalyst in chemical methods.

Question 44. What Is A Solvent?

Answer :

According to the US Solvent Council, "A solvent is a liquid which has the potential to dissolve, droop, or extract other materials with out chemical change to the material or solvent. Solvents make it viable to technique, apply, easy, or separate materials.

Question 45. What Are The Three Classes Of Organic Solvents?

Answer :

Typically, organic solvents may be cut up up within the following instructions: Oxygenated, Hydrocarbon, and Halogenated. Oxygenated solvents include alcohols, glycol ethers, ketones, esters, and glycol ether esters. Hydrocarbon solvents encompass aliphatics and aromatics. Halogenated solvents encompass those which are chlorinated normally.

Question forty six. What Is Happening When Paint Dries?

Answer :

During the manufacture of paint, solvents are delivered to make the paint thinner in order that it is able to be carried out to diverse surfaces. Once the paint is carried out, the solvents evaporate and the resins and pigments that make up the paint for a thin, strong layer on the surface.

Question forty seven. What Is Quicklime And What Are The Uses?

Answer :

Quicklime (Calcium Oxide) is a good scavenger of moisture in its dehydrated state. It is likewise cheap, as compared to orthe scavengers including silica gel, drierite, oxazolidines, etc. It is generally determined in water sensitive paint formulations (together with polyurethanes and polyureas).

Question 48. What Are Pcb's?

Answer :

PCB is a generally used acronym for "PolyChlorinated Biphenyls". These compounds are well-known for the disposal problems that they pose to the chemical enterprise.

Question forty nine. How Can Separation Of Chiral Chemicals Affect The Chemical And/or Pharmaceutical Industries?

Answer :

This enantiomers (left [S] or proper [R] oriented) versions of the same compound can have very distinctive residences; this improvement has been sizable particularly inside the pharmaceutical enterprise. For instance, the drug Seldane is a racemic combination of each S and R variations of the drug's molecules. Through chiral separation generation, Hoechst changed into capable of convey the drug Allegra to market in handiest three years (a ways much less time than is generally important). Hoechst was able to bypass toxicity testing due to the fact Allegra is a unmarried chiral form of its molecule. By chiral separation, the most of the facet outcomes of Seldane had been averted in Allegra.

Question 50. Can Asphalt Be Recycled To Form A Useful Product?

Answer :

Asphalt may be ground into small pieces and emulsified to form a 70% oil/30% water mixture. This gasoline can be used to power boilers. It has a heating price of 6,six hundred kcal/kg and is stated to be solid for approximately 6 months.

Question fifty one. What Is A Surfactant?

Answer :

A surfactant is a chemical that reduces the surface tension of natural liquid or a aggregate of liquids.

Question fifty two. What Is A Good Source Of Surfactant Information On The Internet?

Answer :

Check out the Surfactant Virtual Library at the link underneath.

Question fifty three. What Is The Wet Bulb Globe Temperature (wbgt)?

Answer :

The sultriness of the ambient environment is extra than a comfort thing. For people, soldiers and athletes, excessive stages of sultriness may also bring about warmness stress that might thoroughly be existence threaten. To determine the real diploma of sultriness in a quantifiable manner, the Wet Bulb Globe Temperature (WBGT) index is used. It consists of the results of humidity, air speed, air temperature and the radiant heating thing (from the solar). This index became evolved through the U.S. Military within the 1950's and has end up broadly conventional for industrial temperature measurements to defend personnel. It combines 3 temperature readings: the moist bulb temperature; the normal dry bulb temperature and a black bulb globe temperature. There also are contraptions available, which degree WBGT index immediately, combining the 3 elements and their suitable weighting values.

Question 54. How Can Metals Be Removed From Aqueous Waste Streams?

Answer :

Precipitation is broadly used to get rid of metals from waste streams. The soluble heavy-metallic salts may be converted to insoluble salts so that it will precipitate and may then be removed with the aid of rationalization, filtration, or settling.

Question fifty five. What Are Some Common Precipitating Agents Used To Remove Metals From Aqueous Waste Streams?

Answer :

Perhaps the maximum not unusual retailers used are:

Metal hydroxides
Lime or caustic soda
Metal sulfides
Alum or ferric salts
Phosphate or carbonate ions
Question 56. What Types Of Metals Are Typically Removed Via Chemical Precipitation?

Answer :

Some of the extra commonplace metals or different substances removed via precipitation consist of:

Aluminum
Arsenic
Barium
Cadmium
Calcium
Trivalent chromium
Hexavelent chromium
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Selenium
Zinc
Question fifty seven. How Can Hexavalent Chromium Be Removed From Aqueous Waste Streams?

Answer :

One option is to use ferrous sulfate to lessen the hexavalent chromium to a much less poisonous, trivalent chromium form that wills precipitate out of the answer. Trivalent chromium can then be reduced via sodium hydroxide.

Question fifty eight. How Can Arsenic Be Removed From Aqueous Waste Streams?

Answer :

Often instances, ferric chloride is brought to this type of stream. The ferric chloride aids within the formation of floc to agglomerate great arsenic particles which could then be eliminated via mechanical way.

Question fifty nine. How Can I Treat A Waste Stream Containing Both Hexavalent Chromium And Arsenic?

Answer :

Waste streams that incorporate these kinds of mixtures are regularly dealt with in  or more decreasing tanks. Strong reducing dealers inclusive of sodium metabisulfite, sulfur dioxide, and sodium bisulfite are regularly used.

Question 60. How Many Grams Per Liter Would There Be In A 0.35 N (normality) Citric Acid Solution?

Answer :

The normality of a solution is the range of gram-equivalent weights of the dissolved substance in keeping with liter of solution. The gram-equivalent weight of the dissolved substance is the molecular weight of the dissolved substance divided by the hydrogen equal of the dissolved substance. Citric acid has a molecular weight of 192.12 and it carries 3 hydrogen equivalents (i.E., three COOH businesses). Thus, the gram equal weight of the citric acid dissolved in water is 192.12/3 = 64.04 grams. Therefore 0.35 Normal citric acid would have (0.35)(sixty four.4) = 22.Forty one grams of citric acid per liter of solution.

Question sixty one. What Is An Additive?

Answer :

An additive is some thing that is brought to a procedure that isn't a basic raw cloth. It is normally found in such small portions that it does not intervene with very last product satisfactory. It is commonly added to behave as an enhancer or to save you some undesirable response. For example, anti-foam components are added to columns, evaporators, reactors, and many others. To save you foaming. Inhibitors are brought to Styrene systems to save you polymerization. A well-known additive is a detergent delivered to motor oils and gasoline to preserve your engine clean.

Question 62. What Chemical Is Used To Expand Air Bags In Such A Short Amount Of Time?

Answer :

That chemical is sodium azide (NaN3) that's a strong propellant that may be electrically ignited to shape nitrogen fuel nearly immediately.

Question sixty three. What Steps Can Be Taken To Avoid Stress Corrosion Cracking (scc) In Steel Vessels Used For Storing Anhydrous Ammonia?

Answer :

The U.S. National Board of Pressure Vessel Inspectors recommends the following in certainly one of their traditional articles:

Pressure vessels have to be absolutely stress relieved or fabricated with heads that are hot-shaped or strain relieved.
Extreme care must be used to take away air from the ammonia systems; new vessels must be thoroughly purged to remove air infection.
Ammonia must incorporate at the least 0.2 percent water to inhibit SCC. Source: National Board of Pressure Vessel Inspectors
Question 64. How Can Wet Carbon Dioxide Be Responsible For A Corrosion Problem In Iron-containing Metals?

Answer :

Carbon dioxide reacts with water in line with the subsequent equation: CO2 + H2O --> HCO3- + H+ As the awareness of CO2 increases, so does the awareness of the H+ ion. This ion can then react with Fe in metals as follows: Fe + 2H+ --> 2H (atom) + Fe2+ As corrosion proceeds, the ferrous ions produced can react with the bicarbonate ions to form ferrous carbonate, which precipitates as a scale.

Question sixty five. Is It Possible To Compare The Resistance To Chloride Attack Of Several Materials Of Construction?

Answer :

The Pitting Resistance Equivalent Index (PRE) may be used for one of these comparison if the chemical make-up of each material is understood. The formula for the PRE is PRE = % Cr + (three.Three x % Mo) + (30 x % N).

Question 66. What Is The Angle Of Repose And What Are Its Applications In The Chemical Industry?

Answer :

The dictionary defines "attitude of repose" as "the inclination of a aircraft at which a frame positioned at the plane would continue to be at rest, or if in motion would roll or slide down with uniform speed; the perspective at which the various styles of earth will stand when abandoned to them”. Applications to the chemical industry...Reflect onconsideration on the design of the conical section of a garage bin. The fabric could now not fall out the lowest, as we may also need. This concept is likewise essential inside the design of device designed to transport bulk solids...For the same motives.

Question 67. How Is Waste Heat Boilers Categorized?

Answer :

Chemical vegetation -(hydrogen, nitrogen, sulfuric acid, sulfur recuperation) Incineration plants-(fumes, chemicals, municipal solid waste) Refineries-(cat cracker, CO off gases) Cogeneration, combined cycle plants-(fuel turbine, diesel engine exhaust) Furnaces, kilns-(exhaust gases) See a whole desk on the link under.

Question sixty eight. How Do You Design A Vapor-liquid Separator Or A Flash Drum?

Answer :

The size of a vapor-liquid separator must be dictated by the predicted drift charge of vapor and liquid from the vessel. The following sizing method is primarily based on the idea that the ones waft rates are acknowledged. Use a vertical strain vessel with a duration-to-diameter ratio of about three to 4, and length the vessel to provide approximately five mins of liquid inventory between the regular liquid level and the bottom of the vessel (with the ordinary liquid degree being at about the vessel's half of-complete level).

At the vapor outlet, offer a de-entraining mesh section in the vessel such that the vapor must skip thru that mesh before it could go away the vessel. Depending upon how much liquid go with the flow you assume, the liquid outlet line should likely have a degree control valve.

Question 69. How Can Viscosity Affect The Design Of A Mixer?

Answer :

For Newtonian fluids, which will have a steady viscosity at all impeller speeds, most layout correlations will carry out satisfactorily for viscosities up to five,000 cP. Above 5,000 cP, estimating errors from 20% to 50% can bring about the sizing of the agitator.

Question 70. What Information Is Needed To Specify A Mixer?

Answer :

Specific Gravity
Fluid Viscosity
Phase to be dispersed
Solid-liquid structures
The settling velocities of the ten, 50, and 90 percent weight fractions of the particle size distribution should be available. Five. For gasoline systems, the same old and actual drift fees will be wanted.

Question seventy one. Is There Any Way To Slow Coke Formation In Ethylene Furnaces?

Answer :

Westaim Corporation has a industrial process for making use of a unique coating to the tubes utilized in ethylene furnaces. Westaim claims that coke buildup is decreased to at least one-forth to 1-10th of the ordinary fee. The coating consists of a combination of metallic, ceramic powder, and a polymer. Once the coating is carried out, the tubes are then warmness-handled and reacted with an unspecified fuel. Welds cannot be lined with this method.

Question seventy two. What Are Some Typical Applications For Glass-covered Reactors?

Answer :

Glass-lined device offers superior protection to all mineral acids in any respect attention and temperatures. One exception is hydrofluoric acid. They are also used is excessive-purity methods wherein cleanliness is very crucial. Using glass-lined system assist get rid of the opportunity of steel infection. A 0.33 software is in polymerization. Metallic vessels occasionally generally tend to permit the polymer to paste to the partitions of the vessels at the same time as glass-covered vessels have correct anti-stick properties.

Question seventy three. At What Temperature Is Glass Fused To Steel In The Making Of Glass-coated Equipment?

Answer :

The borosilicate glass is generally fused to carbon metallic at a temperature of about 800 0C.

Question 74. How Are Vessel Lined With Glass Or How Are They Coated?

Answer :

First, the glass combination is smelted for shape the right recipe based on temperature and strain necessities of the vessel. Then the glass is floor into tiny debris and suspended in a liquid medium known as a slip. This mixture is then spayed onto the floor to be lined. The vessel is then heated to 800 0C to bond the glass to the metal (typically carbon metallic). The vessel is then slowly cooled.

Question seventy five. Are There Any General Rules That Should Be Considered When Designing A Slurry Piping System?

Answer :

The following are objects to remember whilst designing a piping machine on the way to delivery slurries:

Whenever feasible, piping should be designed to be self-draining
Manual draining ought to be established to drain sections of the piping while self-draining is not feasible
Blow-out or rod-out connections need to be provided to clean lines in places wherein plugging is likely or ought to occur
Access flanges have to be provided at T-connections
Manifolds ought to have flanged rather than capped connections to permit for clean get entry to
Clean-out connections have to be furnished on BOTH facets of main line valves in order that flushing can take location in either route
Break flanges need to be supplied each 20 feet of horizontal pipe or after every  changes in direction
Question 76. What Is The Method Of Determining Maximum Differential Pressure During Hydro Testing Of Shell And Tube Heat Exchangers?

Answer :

Mr. Richard Lee of Plumlee International Consulting generally warmth exchangers have two sets of take a look at pressures in line with facet, one for energy checks, and the other for "working" or "leak" checks. The strength checks are set by using the design code and if you have the original layout information sheets on your equipment then the records ought to be shown on those. If you do not then you will have to do the calculations yourself, the precise method will depend on which layout code you operate, the most common one being TEMA (which makes use of the ANSI/ASME stress vessel code for reference on this area).

Most shell and tube exchangers are designed such that every facet of the unit will face up to the whole layout strain, with handiest atmospheric pressure on the opposite side. In order to shop money, some large gadgets will have the tube-sheets specially designed to withstand handiest a much lower differential pressure (requiring each aspects to be examined simultaneously). This vital information have to be shall quite honestly at the layout sheets and on the vessel nameplate (assuming that either are available). If the simplest want is to check that a gasket has been well set up then it may be permissible to perform a lower pressure check based on the running stress. The acceptability of this decrease strain test will regularly depend on the results of a leak.

Question seventy seven. What Is A Good Source Of Information For The Design Of Pressure Vessels?

Answer :

Pressure Vessel Handbook Author = Eugene F. Megyesy Publisher = Pressure Vessel Handbook Publ., Inc. P.O. Box 35365 Tulsa, OK 74153 Page 18 tells you the way to calculate a pressure vessel's wall thickness; page 176 tells how to calculate an API Std. 650 Storage tank wall thickness. The rest of the book is a goldmine for younger engineers - specially CHE's involved in vessel design. It also offers all of the statistics you require for supports, nozzles, head design, piping, ladders, platforms, and so on.

Question seventy eight. Are There Flow Velocity Restrictions To Avoid Static Charge Build Up In Pipelines?

Answer :

There is an Australian preferred "AS1020 (1984) - Control of unwanted Static Electricity" In it, there is a desk for flammable hydrocarbons as follows:

Pipe Size (mm) Max Velocity (m/s)

10    eight

25   four.Nine

50   three.5

one hundred 2.5

two hundred 1.8

400 1.Three

600+ 1.0

This is primarily based on natural hydrocarbons, and there's a correction, which may be carried out for fluids of various conductivity. Methanol has a higher polarity than hydrocarbons and for this reason is greater conductive. The resistivity of diesel is 1013 ohm-m vs 108 for methanol. In addition to this, ordinary piping design guidelines must however be observed, which includes suitable earthing, and ensuring go out velocities into tanks of one m/s.

Question 79. What Are Some Guidelines For Sizing A Psv For A Fire Scenario On A Vessel In A Refinery Service?

Answer :

Sizing a PSV for your vessel is a matter of calculating how a good deal heat is inputted from the fireplace. API-520 makes use of Q = FA0.82 wherein Q is BTU/hr, F is the insulation element (commonly taken as 1.0 but can be less than 1.0 if your insulation will continue to be effective at some point of the fireplace and now not be dislodged by way of hearth hoses) and ultimately, A is the outside area in ft2. The vapor load is then the total warmness input from the fireplace divided by the liquid's latent heat (BTU/lb).

As a fluid processes its crucial pressure, the latent heat because it boils decreases so the relieving waft price will increase. At the critical factor, the l




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