45 + Interview Questions in Real Gases: Equations Of State in Basic Chemical Engineering Page 1 InterviewSolution

1.	A process is carried out for the feed mixture of 90% air and 10% water vapor, the compressor recovered 90% of water, what is the exit pressure of the compressor if the partial pressure of water vapor is 50 mm Hg?(a) 286.1 mm Hg(b) 396.4 mm Hg(c) 458.7 mm Hg(d) 529.5 mm HgThe question was asked by my college director while I was bunking the class.My doubt is from Condensation topic in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» CORRECT option is (c) 458.7 mm HG Explanation: EXIT components, water: 0.1*0.1 = 0.01, AIR: 0.9, => water = 0.0109 => Total exit pressure = 50/0.109 = 458.7 mm Hg.

Discussion

2.	Pressure of a gas at temperature T is P, What is the pressure of the gas at 2T, use B = 1?(a) Pe^1/T(b) Pe^1/2T(c) Pe^1/3T(d) Pe^1/4TI have been asked this question in an online interview.My enquiry is from Modeling and Predicting Vapor Pressure topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right ANSWER is (b) Pe^1/2T Explanation: LN P/P2 = 1*(1/2T – 1/T), => P2 = Pe^1/2T.

Discussion

3.	A process is carried out for the feed mixture of 40% air and 60% oxygen, the compressor recovered 2% of oxygen, what is the exit pressure of the compressor, if the partial pressure of oxygen vapor is 5 mm Hg?(a) 2.4 mm Hg(b) 4.8 mm Hg(c) 6.5 mm Hg(d) 8.4 mm HgThis question was posed to me during an interview for a job.Origin of the question is Condensation topic in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right option is (a) 2.4 MM HG Easy explanation: Exit components, oxygen: 0.6*0.98 = 0.588, air: 0.4, => yoxygen= 0.588/0.988 = 0.595, => TOTAL exit PRESSURE = 5/0.595 = 8.4 mm Hg.

Discussion

4.	A process is carried out for the feed mixture of 50% air and 50% methane vapor, the compressor recovered 20% of methane, what is the exit pressure of the compressor, if the partial pressure of methane vapor is 25 mm Hg?(a) 56.3 mm Hg(b) 78.9 mm Hg(c) 92.1 mm Hg(d) 98.7 mm HgThis question was addressed to me in homework.The origin of the question is Condensation in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct option is (a) 56.3 mm HG To explain: EXIT components, METHANE: 0.5*0.8 = 0.4, air: 0.5, => ymethane= 0.4/0.9 = 0.444, => TOTAL exit PRESSURE = 25/0.444 = 56.3 mm Hg.

Discussion

5.	A process is carried out for the feed mixture of 80% air and 20% CO2, the compressor recovered 50% of CO2, what is the exit pressure of the compressor, if the partial pressure of CO2 is 15 mm Hg?(a) 135 mm Hg(b) 145 mm Hg(c) 175 mm Hg(d) 200 mm HgThis question was posed to me by my college director while I was bunking the class.Query is from Condensation in chapter Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct choice is (a) 135 mm Hg To explain I would say: EXIT components, CO2: 0.2*0.5 = 0.1, air: 0.8, => YCO2 = 0.1/0.9 = 0.111, => TOTAL exit PRESSURE = 15/0.111 = 135 mm Hg.

Discussion

6.	A process is carried out for the feed mixture of 95% air and 5% ammonia vapor, the compressor recovered 40% of ammonia, what is the exit pressure of the compressor, if the partial pressure of ammonia vapor is 10 mm Hg?(a) 225.4 mm Hg(b) 326.8 mm Hg(c) 451.2 mm Hg(d) 593.5 mm HgThe question was posed to me by my school teacher while I was bunking the class.I want to ask this question from Condensation in chapter Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right CHOICE is (b) 326.8 mm HG Easiest explanation: Exit COMPONENTS, ammonia: 0.05*0.6 = 0.03, AIR: 0.95, => yammonia = 0.03/0.98 = 0.0306, => Total exit PRESSURE = 10/0.0306 = 326.8 mm Hg.

Discussion

7.	What is the fraction of water vapor at 27^oC and 1 atm, if the fraction of water vapor at 127^oC and 1 atm is 0.8?(a) 0.2(b) 0.4(c) 0.6(d) 0.8This question was posed to me in an interview for internship.My question is from Condensation in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct CHOICE is (c) 0.6 The explanation: Fraction of WATER VAPOR at 127^oC and 1 ATM = 0.8*300/400 = 0.6.

Discussion

8.	If the fraction of water vapor at 27^oC and 5 atm is 0.5, then what is the fraction of water vapor at 27^oC and 1 atm?(a) 0.1(b) 0.2(c) 0.5(d) 0.8This question was posed to me during an interview.I would like to ask this question from Condensation topic in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The CORRECT ANSWER is (a) 0.1 To elaborate: Fraction of WATER VAPOR at 27^oC and 1 atm = 0.5/5 = 0.1.

Discussion

9.	Condensation starts at which point?(a) Dew point(b) Bubble point(c) Triple point(d) None of the mentionedThis question was posed to me during a job interview.My doubt is from Condensation topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The CORRECT OPTION is (a) Dew point The best I can EXPLAIN: A dew point is a temperature at which condensation starts.

Discussion

10.	Which of the following is not a way of condensation of vapor?(a) Cooling at constant volume(b) Cooling at constant pressure(c) Compress it isothermally(d) Compress itI got this question during an interview.Origin of the question is Condensation topic in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct choice is (d) COMPRESS it Explanation: COMPRESSING a GAS and its temperature is increasing does not condense the vapor, compressing vapor at constant temperature is a WAY of CONDENSATION.

Discussion

11.	Which of the following defines condensation?(a) Change of solid to vapor(b) Change of vapor to liquid(c) Change of liquid to vapor(d) Change of vapor to solidI got this question in homework.My doubt is from Condensation topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct option is (b) CHANGE of VAPOR to LIQUID For explanation: Condensation is PHASE change from vapor to liquid.

Discussion

12.	10 KPa of water vapor at 27^oC is saturated with air in a system, what is the mole fraction of air?(a) 0.21(b) 0.46(c) 0.79(d) 0.91This question was posed to me during an interview for a job.I need to ask this question from Saturation in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» CORRECT CHOICE is (d) 0.91 Explanation: FRACTION of AIR = 101.3/(10 + 101.3) = 0.91.

Discussion

13.	100 KPa of water vapor at 27^oC is saturated with air in a system, what is the mole fraction of air?(a) 0.230(b) 0.306(c) 0.425(d) 0.503I had been asked this question by my college professor while I was bunking the class.Question is taken from Saturation in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right ANSWER is (d) 0.503 For EXPLANATION: FRACTION of air = 101.3/(100 + 101.3) = 0.503.

Discussion

14.	Ethanol is burnt with required amount of O2 at atmospheric pressure, the conversion of ethanol is 100%, what is the pressure at due point?(a) 0.2 atm(b) 0.4 atm(c) 0.6 atm(d) 0.8 atmThe question was posed to me in an interview.Query is from Saturation topic in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right choice is (c) 0.6 atm Explanation: C2H5OH + 3O2 -> 2CO2 + 3H2O, Basis: 100 moles of ETHANOL, => moles of O2 reacted = 300, => Product CONTAINS, moles of CO2 = 200, H2O = 300, fraction of H2O = 0.6, => PRESSURE at due point = 0.6*1 = 0.6 atm.

Discussion

15.	CH4 is burnt with 100% excess O2 at atmospheric pressure, if CH4 conversion is 100%, what is the pressure at dew point?(a) 0.2 atm(b) 0.4 atm(c) 0.6 atm(d) 0.8 atmI got this question in unit test.My doubt stems from Saturation in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct CHOICE is (b) 0.4 atm The best I can explain: CH4 + 2O2 -> CO2 + 2H2O, Basis: 100 moles of CH4, => moles of O2 reacted = 200, => Product contains, moles of CO2 = 100, moles of H2O = 200, moles of O2 = 200. => FRACTION of H2O = 0.4, => Pressure at due point = 1*0.4 = 0.4 atm.

Discussion

16.	Ethane is burnt with 20% excess O2 at 2 atm, conversion rate of ethane is 50%, what is the pressure at due point?(a) 0.45 atm(b) 0.75 atm(c) 0.9 atm(d) 1 atmThe question was asked in an international level competition.Origin of the question is Saturation in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer»

Discussion

17.	The partial pressure of a system at 49^oC is 125 mm Hg and saturated ammonia vapor has partial pressure 20 mm Hg at 49^oC, what is the fraction of ammonia vapor in the system?(a) 0.04(b) 0.08(c) 0.16(d) 0.24This question was posed to me during an online interview.My question is based upon Saturation in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct CHOICE is (C) 0.16 Explanation: FRACTION of ammonia VAPOR = 20/125 = 0.16.

Discussion

18.	What is the dew point of water at standard conditions?(a) 32^oF(b) 212^oF(c) 372^oF(d) 584^oFI got this question during an interview.My doubt is from Saturation topic in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct choice is (B) 212^oF To explain: Dew POINT of WATER at STANDARD conditions is 100^oC = 212^oF.

Discussion

19.	A system has partial pressure 500 mm Hg and the saturated water vapor has partial pressure 25 mm Hg, what is the fraction of water vapor in the system?(a) 0.01(b) 0.05(c) 0.1(d) 0.5I got this question in an interview for job.This is a very interesting question from Saturation topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct CHOICE is (B) 0.05 The explanation is: FRACTION of WATER vapor = 25/500 = 0.05.

Discussion

20.	A container has vapor H2O with partial pressure 9 atm, what is fraction of air in the vessel?(a) 0.1(b) 0.4(c) 0.7(d) 0.9I got this question in a national level competition.This intriguing question originated from Saturation topic in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct option is (a) 0.1 Easiest explanation: PRESSURE of air = 1 ATM, => FRACTION of air = 1/(1 + 9) = 0.1.

Discussion

21.	A vessel contains air and vapor H2O, if the partial pressure of vapor H2O is 4 atm and pressure of air is 1 atm, what is the fraction of vapor H2O in vessel?(a) 0.25(b) 0.5(c) 0.75(d) 0.8This question was addressed to me in semester exam.Asked question is from Saturation in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» CORRECT option is (c) 0.75 The BEST explanation: YH2O = 15/(15 + 5) = 0.75.

Discussion

22.	The pressure of a compound at 200 K is 10 mm Hg and at 400 K it is 50 mm Hg, what is the pressure at T = 250 K?(a) 18.1 mm Hg(b) 24.2 mm Hg(c) 36.3 mm Hg(d) 48.4 mm HgThe question was posed to me in unit test.I'm obligated to ask this question of Modeling and Predicting Vapor Pressure in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» RIGHT CHOICE is (a) 18.1 mm HG To elaborate: Let the pressure of the COMPOUND is given by ln p* = a + b/T, => ln 10 = a + b/200, ln 50 = a + b/400, => ln 5 = -b/400, => b = -643.7, => a = 5.5, => At T = 250 K, ln p* = 5.5 – 643.7/250 = 2.9, p = 18.1 mm Hg.

Discussion

23.	What is the vapor pressure of ammonia at 305 K, if it is given that the vapor pressure of ammonia at 315 K is 5 mm Hg and at 325 K it is 6 mm Hg?(a) 1 mm Hg(b) 2 mm Hg(c) 3 mm Hg(d) 4 mm HgThe question was posed to me during a job interview.I would like to ask this question from Modeling and Predicting Vapor Pressure in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» CORRECT answer is (d) 4 MM Hg Explanation: p305K = 5 – (315 – 305)*(6 – 5)/(325 – 315) = 5 – 1 = 4 mm Hg.

Discussion

24.	For CaOCl2, the rate of evaporation is given by W = 325p^0.5M/T^1.5 g/liter, where T is in K, p in mm Hg, and M is molecular weight, if its pressure is given by ln p* = 25 – 2700/T, what is the evaporation rate at T = 150 K?(a) 256 g/liter(b) 499 g/liter(c) 571 g/liter(d) 744 g/literI had been asked this question during a job interview.My doubt is from Modeling and Predicting Vapor Pressure in chapter Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right option is (d) 744 g/liter For EXPLANATION I would SAY: ln p* = 25 – 2700/150 = 7, => p = 1096.6 mm Hg, => W = 325(1096.6)^0.5*127/150^1.5 = 744 g/liter.

Discussion

25.	The vapor pressure of a compound in a liquid phase is given by ln p* = 21 – 2800/T, and in solid phase it is given by ln p* = 28 – 3500/T, what is the sublimation temperature of the compound?(a) 100 K(b) 120 K(c) 150 K(d) 200 KI got this question in final exam.My question comes from Modeling and Predicting Vapor Pressure in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct option is (a) 100 K For EXPLANATION: At sublimation point pressure and TEMPERATURE of both the PHASES will be same, => 21 – 2800/T = 28 – 3500/T, => T = 100 K.

Discussion

26.	The vapor pressure of liquid benzene is given by ln p* = 15 – 1280/T, and that of vapor benzene is given by ln p* = 23 – 2560/T, what is the boiling point of benzene?(a) 160 K(b) 200 K(c) 240 K(d) 300 KThis question was posed to me by my school principal while I was bunking the class.I'd like to ask this question from Modeling and Predicting Vapor Pressure topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The CORRECT option is (a) 160 K To explain: At boiling point PRESSURE and TEMPERATURE of both the phases will be same, => 23 – 2560/T = 15 – 1280/T, => 8 = 1280/T, => T = 160K.

Discussion

27.	At triple point, vapor pressure of ice is given by ln p* = 18 – 2560/T, and vapor pressure of water is given by ln p* = 28 – 5120/T, what is the temperature at triple point?(a) 225 K(b) 256 K(c) 320 K(d) 400 KI got this question in an interview for internship.The above asked question is from Modeling and Predicting Vapor Pressure in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct choice is (B) 256 K Easy explanation: At triple point PRESSURE and temperature of all the phases BECOMES same, => 18 – 2560/T = 28 – 5120/T, => 10 = 2560/T, => T = 256 K.

Discussion

28.	A liquid evaporates first at which of the following conditions?(a) High attraction forces(b) Low attraction forces(c) Low vapor pressure(d) High boiling pointI got this question in an interview for job.The above asked question is from Modeling and Predicting Vapor Pressure topic in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right OPTION is (b) Low ATTRACTION FORCES Best explanation: A LIQUID evaporates first at low attraction forces.

Discussion

29.	Pressure of a gas at 127^oC is 10 mm Hg and the pressure at 527^oC is 20 Pa, what is the value of B?(a) 225.1(b) 365.5(c) 499.2(d) 554.5This question was posed to me during an online interview.This is a very interesting question from Modeling and Predicting Vapor Pressure in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct ANSWER is (d) 554.5 Best explanation: LN 10/20 = B (1/800 – 1/400), => B = 554.5.

Discussion

30.	At which of the following values of pressure a solid melts first?(a) 5 atm(b) 720 mm Hg(c) 500 KPa(d) 40 TorrI have been asked this question in unit test.This key question is from Modeling and Predicting Vapor Pressure topic in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right option is (a) 5 ATM The explanation is: A solid MELTS FIRST at the highest PRESSURE which is 5 atm.

Discussion

31.	Temperature of SO2 at 5 Pa is 395 K and at 10 Pa temperature is 420 K, what is the temperature at 6 Pa?(a) 400 K(b) 405 K(c) 410 K(d) 415 KThis question was posed to me in an interview for internship.This question is from Modeling and Predicting Vapor Pressure in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right ANSWER is (a) 400 K Explanation: Using LINEAR INTERPOLATION, T6Pa = 395 + (6 – 5)*(420 – 395)/(10 – 5) = 395 + 5 = 400 K.

Discussion

32.	What is the pressure of CO2 at 325 K, if it is given that pressure at 330 K is 6 Pa, and pressure at 320 K is 4 Pa?(a) 4.5 Pa(b) 5 Pa(c) 5.5 Pa(d) 6 PaThe question was asked in a job interview.Question is from Modeling and Predicting Vapor Pressure topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct option is (b) 5 Pa Explanation: Using LINEAR INTERPOLATION, P325K = 4 + (325 – 320)(6 – 4)/(330 – 320) = 4 + 52/10 = 5 Pa.

Discussion

33.	If the pressure of a gas at 27^oC is 15 mm Hg, what will be its pressure at 127^oC, use B = 5 X 10^3, C = 0, T is in kelvin and P is in mm Hg?(a) 579 mm Hg(b) 775 mm Hg(c) 961 mm Hg(d) 999 mm HgI had been asked this question during an online interview.My enquiry is from Modeling and Predicting Vapor Pressure topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right option is (c) 961 MM Hg The best explanation: LN P1/P2 = B (1/T2 – 1/T1), => ln 15/P2 = 5 X 10^3 (1/400 – 1/300), P2 = 961 mm Hg.

Discussion

34.	A material’s mass is given by the equation, m = 32P^0.02/T^0.5, where T is in Kelvin, m is in Kg and P is in mm Hg, what is the mass of material at 127^oC, use A = 10, B = 6 X 10^3 and C = 0?(a) 1.44 Kg(b) 1.69 Kg(c) 1.96 Kg(d) 2.25 KgThe question was asked by my college professor while I was bunking the class.My question is based upon Modeling and Predicting Vapor Pressure topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» RIGHT option is (a) 1.44 Kg Explanation: ln p* = A – B/(C + T) = 10 – 6 X 10^3/(400) = -5, => p = 0.0067 mm Hg, => m = 32*(0.0067)^0.02/400^0.5 = 1.44 Kg.

Discussion

35.	What is the pressure of a gas at T = 227^oC, it is given that A = 5, B = 4 X 104 and C = 0 if T is in kelvin and p in mm Hg?(a) 0.024 mm Hg(b) 0.049 mm Hg(c) 0.075 mm Hg(d) 0.096 mm HgThe question was asked in an interview for job.Question is from Modeling and Predicting Vapor Pressure topic in chapter Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct option is (b) 0.049 mm HG To explain: ln p* = A – B/(C + T), => ln p = 5 – 4 X 10^3/(273 +227) = -3, => p = 0.049 mm Hg.

Discussion

36.	What is the unit of λ in the SRK equation?(a) Liter/mole(b) Mole/Liter(c) Atm(liter/mole)(d) It is dimensionlessThis question was addressed to me in homework.This is a very interesting question from Equations of State topic in portion Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct answer is (d) It is DIMENSIONLESS Explanation: In the SRK EQUATION, λ is a dimensionless FUNCTION of REDUCED TEMPERATURE.

Discussion

37.	What is the unit of ‘a’ in RK equation?(a) Liter/mole(b) Atm(liter/mole)(c) Atm(liter/mole)K^0.5(d) Atm(liter/mole)KThe question was posed to me in an internship interview.This intriguing question comes from Equations of State in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct option is (c) Atm(liter/mole)K^0.5 The explanation: RK equation is p = RT/(V – B) – a/[T^0.5V(V + b)], => UNIT of a = atm(liter/mole)K^0.5.

Discussion

38.	A container is filled with a gas at 10 atm with molar volume 1 liter/mole, if B = – 0.053 liter/mole, C = 0.0026 liter^2/mole^2, what is the temperature of gas? (Use virial equation, neglect higher terms)(a) 128.2 K(b) 156.9 K(c) 198.5 K(d) 243.6 KThe question was asked in final exam.This is a very interesting question from Equations of State in chapter Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» RIGHT choice is (a) 128.2 K To explain: PV = RT(1 + B/V + C/V^2), => T = 101/[0.0821(1 – 0.053/1 + 0.0026/1^2)] = 128.2 K.

Discussion

39.	What is the unit of ‘b’ in Peng Robinson equation?(a) Liter/mole(b) Liter^2/mole^2(c) Mole/Liter(d) Mole^2/Liter^2I got this question in semester exam.I need to ask this question from Equations of State in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» RIGHT option is (a) Liter/mole Best explanation: PENG Robinson equation is p = RT/(V – b) – aα/[V(V + b) + b(V – b)], => unit of b = unit of MOLAR volume = liter/mole.

Discussion

40.	A container has O2 at 5 atm and molar volume 2 liter/mole, if a = 9.24 atm(liter/mole), b = 0.0907 liter/mole, what is the temperature of O2? (Use vander waal equation)(a) 140 K(b) 150 K(c) 170 K(d) 190 KI had been asked this question in examination.The doubt is from Equations of State topic in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right answer is (c) 170 K To EXPLAIN I would SAY: (p + a/V^2)(V – b) = RT, => T = (5 + 9.24/2^2)(2 – 0.0907)/0.0821 = 170 K.

Discussion

41.	A container has H2 at 27^oC and molar volume 1 liter/mole, if a = 9.24 atm(liter/mole), b = 0.0907 liter/mole, what is the temperature of H2? (Use vander waal equation)(a) 7.5 atm(b) 12.4 atm(c) 15.6 atm(d) 17.8 atmThe question was asked by my school teacher while I was bunking the class.My question is based upon Equations of State in section Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct option is (d) 17.8 atm Easiest EXPLANATION: (p + a/V^2)(V – b) = RT, => p = 0.0821*300/(1 – 0.0907) – 9.24/1^2 = 17.8 atm.

Discussion

42.	What is the pressure of CO2 at 0^oC, molar volume = 4 liter/mole, if B = – 0.053 liter/mole, C = 0.0026 liter^2/mole^2? (Use virial equation, neglect higher terms)(a) 2.4 atm(b) 4.1 atm(c) 5.5 atm(d) 6.9 atmI had been asked this question in an interview for job.Asked question is from Equations of State topic in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Right option is (C) 5.5 atm The BEST EXPLANATION: pV = RT(1 + B/V + C/V^2), => p = (0.0821*273/4)(1 – 0.053/4 + 0.0026/16) = 5.5 atm.

Discussion

43.	If the vander waal equation has only one root, what is the relation between a and b?(a) 729a = pb^2(b) 243a = pb^2(c) 81a = pb^2(d) 9a = pb^2The question was asked in unit test.I'm obligated to ask this question of Equations of State topic in chapter Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» The correct option is (a) 729a = pb^2 To elaborate: Vander WAAL equation, V^3 – (NB + nRT/p)V^2 + (N^2a/p)V – n^3ab/p = 0, comparing with (V – Vc)^3 = 0, => 3n(a/p)^1/2 = n(ab/p)^1/3, => 729a = pb^2.

Discussion

44.	Virial Equation is a ______(a) Arithmetic Progression(b) Geometric Progression(c) Harmonic Progression(d) None of the mentionedThe question was asked in exam.My question is based upon Equations of State in chapter Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» Correct ANSWER is (b) Geometric PROGRESSION For explanation I would SAY: Virial equation is PV = RT (1 + 1/V + 1/V^2 + 1/V^3 + – – – – -), which is a geometric progression.

Discussion

45.	Which of the following is not the equation of state?(a) Van der Waals Equation(b) Charles Equation(c) Holborn Equation(d) Peng Robinson EquationI have been asked this question during an interview.My question is from Equations of State in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering
Answer» RIGHT answer is (b) CHARLES Equation The BEST I can explain: Charles equation is simply P α 1/V which is not the equation of STATE.

Discussion

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