Chemical Engineering Interview Questions
Questions Answers Views Company eMail

According to Shockley equation, the I – V characteristic of a diode is approximated by I = IS [ exp (nVD / VT) – 1 ]. For silicon, let the reverse bias saturation current IS as 0.000000000001. If n is ideality factor with value of 1.5, VT as thermal voltage drop of 0.026 V at room temperature, what is the value of current I that passes through the silicon diode in the heater of evaporator when the forward voltage drop VD = 0.026 V? Please take note that exp is the exponential function with e(1) = 2.718, e(2) = 7.389.

1 2107

In a Laplace Transform Table, the Laplace transfer function of f(t) is F(s). When d(t) = f(t) then 1 = F(s). When x(t) = f(t) then X(s) = F(s). If d(t) is the impulse of a spring when d(t) = kx(t), then derive the equation for the impulse of a spring as X(s) in term of k. Next question : A controller has a transfer function a and the other controller has a transfer function b. The overall transfer function of both controllers is ab. What is the transfer function overall when both controllers have similar transfer function 1 / (Cs k)?

1 1871

In differential centrifugation of cells with diameter D in centimeter, the square of D is given by D x D = [18n ln (RF / RI) ] / [ (RP – RFF) Wt ] where n is the fluid viscosity (poise), RF is the final radius of rotation (cm), RI is the initial radius of rotation (cm), RP is cell density (g/ml), RFF is the fluid density (g/ml), W the square for the rotational velocity in (radians / s) (radians / s), t is the time required to sediment from RI to RF (s). Derive an equation for W as a function for D, n, RF, RI, RP, RFF and t, with the stated units above, in radian

1 1848

At 150 degree Celsius, a mixture of 40 wt % Sn and 60 wt % Pb present, forming phases of alpha and beta. Chemical composition of Sn at each phase : CO (overall) : 40 %, CA (alpha) : 11 %, CB (beta) : 99 %. (a) State 2 reasons for the existences of alpha and beta phases for the mixture of Sn – Pb at 150 degree Celsius. (b) By using Lever Rule, calculate the weight fraction of each phase for alpha, WA = Q / (P Q) and beta, WB = P / (P Q) where Q = CB – CO and P = CO – CA.

1 1746

Solve the first order differential equation : (Z 1)(dy/dx) = xy in term of ln |y| = f(x). Z = (x)(x).

1 1792

In a selection of suitable heating equipment for drying of crystals of biochemical, the one of the lowest current consumption will be chosen for safety consideration. Selection is available : (A) 120 V microwave oven 1800 W. (B) 240 V conventional oven 11000 W. Which one should be chosen and why?

1 1695

A cantilever beam of length L = 3 m carries a uniformly distributed load (UDL) of W = 20 N / m throughout the length. Calculate the bending moment, BM of the beam near the fixed end. What is the shear force, SF at this point? Let SF = -WL, BM = -LWL/2.

1 1895

Question 27 – By using Excel or other easiest programming package, explain how I, the integral of sin x dx from 0 to 3.142 could be approximated using random number. Find the exact value of I.

1 1695

For a Vernier scale of representative fraction (RF) = 1 / 25, calculate the length of the scale for the reading up to 4 metres.

1 2118

Question 29 – For a Vernier scale that consists of 0.11 cm per section, estimate the length on actual standard ruler of 0.1 cm per section for 2.39 m and 0.91 m.

1 1709

Question 30 – Solve the simultaneous equation using simple Excel program : r + s – t = 7, 2r – s = 0, 3r + 2t = 15. Explain the use of functions of MINVERSE and MMULT together with the keyboard C (Ctrl) + S (Shift) + E (Enter).

1 1817

Question 31 – For liquid benzene, the CP constants are : a = 129440, b = - 169.5, c = 0.64781. Reference temperature is 298 K. The temperature of benzene is 60 degree Celsius. Calculate the enthalpy of benzene by using the formula H = a (DT) + (b/2) (T^2 – TREF^2) + (c/3) (T^3 – TREF^3) where ^ is power, DT is temperature difference with TREF = 298 K. H is in J / kmol. DT = T – TREF.

1 1946

Question 32 – Let 1 ^ 1 = 1, 2 ^ 2 = 4, 3 ^ 3 = 27. By using the Excel computer programming – either by Solver or Goal Seek, find the value of v for the Van der Waals equation (P – a / v ^2) (v - b) = RT where a = 18.82, b = 0.1193, P = 2, R = 0.082, T = 5000 for benzene. Describe briefly how to use Solver and Goal Seek in Excel program of computer to find the solution quickly.

1 1699

Question 33 – By using Excel program either on laptop or desktop PC, solve the differential equation dy / dx = -2y + x + 4 with h = 0.005, initial values : x = 0, y = 1. The 4th order Runge-Kutta method provides : y(N + 1) = y(N) + (1/6) (k1 + 2k2 +2k3 + k4), k1 = h [ -2y(N) + x(N) + 4 ], k2 = h { -2 [ y(N) + k1 / 2 ] + x(N) + h / 2 + 4 }, k3 = h { -2 [ y(N) + k2 / 2 ] + x(N) + h / 2 + 4 }, k4 = h { -2 [ y(N) + k3 ] + x(N) + h + 4 }. What is the value of y at x = 0.5?

1 1674

Question 34 – In the distillation of binary systems by Mc Cabe Thiele method, the equation for the line of top section is given by y = [ R / (R + 1) ] x + XD / (R + 1). 2 points on the line are (0.99, 0.99) and (0, 0.36). Find the reflux ratio of R and XD.

1 1790


Post New Chemical Engineering Questions

Un-Answered Questions { Chemical Engineering }

what is the cast iron grade of composition of c-3.06% , Mn- 0.48% , Si-2.38% , S-0.088% , P-0.092% , Cr-0.12% , Ni- 0.012% , Mo-0.00%

1603


What are the main terms in unit operations? What are its characteristics?

611


Explain how can you separate hydrogen peroxide into hydrogen and oxygen?

494


Explain what is a good way to get started in doing a plant-wide steam consumption analysis?

523


Explain global warming from a common man's and an engineer's perspective?

513






What are the steps required to design a vapor-liquid separator or flash drum?

562


How can you control the ph level in our cooling water with respect to ammonia contamination?

586


Why are decomposition reactions called the opposite of combination reactions?

544


What is a "saltation velocity"?

601


The process conditions of the fuel gas are as follows: Temperature = 25 deg C Pressure = 4 bar g Calculate the line size for the fuel gas supply line to the superheater

1736


dear sir/madam, I had applied for the post of officer trainee so plz if u have any papers both technical or aptitude plz inform me on sonalichavan01@gmail.com

1829


Plz if anybody has placement paper of HAL mail me i m Chemical engg my id er.kotnala@gmail.com

1996


Explain the different types of equipments for the conveyance of solids?

489


Define a surfactant?

556


We are having proplem with the persperation smell in ETT/ECHO room in our cardiac hospital.The 2 Ton of AC is not conditioning the environment. We have to use exhaust fan to through out of the room bad air. Could anyone suggest how to coup with this effectively using chemical engineering. Any permanent solution to neutralise the bad smell.The Air freshners are not doing enough instead making a bad odour.

1688