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UNIVERSITITEKNOLOGIP ETRONA.S

FINAL EXAMINATIONSEPTEMBER 2012 SEMESTER

COURSE : CCB1023 PHYSICAL CHEM|STRYDATE : 2nd JANUARY 2013 (WEDNESDAY)TIME : 9.00 AM - 12.00 NOON (3 HOURS)INSTRUCTIONS TO CANDI DATES1. Answer ALL questions from the Questions Booklet.2. Begin EACH answer on a new page in the Answer Booklet.3. lndicate clearly answers that are cancelled, if any.4. Where applicable, show clearly steps taken in arriving at the solutions and indicateALL assumptions.5. Do not open this Question Booklet until instructed,Note : i. There are SEVEN (7) pages in this Question Booklet including thecover page and Appendix.ii. TWO (2) graph papers are provided.

Unrverstti Teknoloqi PETRONAS

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CCB1O231' a' Define and give TWo (2) exampres of the foilowing terms:i. Extensive property.

[2 marks]ii. lntensive property.[2 marks]

b' A gas mixture consists of 300 mg of methane, 1g0 mg of argon, and230 mg of neon in a container. The partiar pressure of neon at 300 Kis 8.8s kpa. Assuming the gas mixture obeys the idear gas raw,calculate:i. The volume of the gas rnixture.

[4 marks]ii. The total pressure of the gas mixture.

[4 marks]

c. A certain gas obeys the Van der waars equation of state witha=0.76 m6pamor-2 with the morar vorume of the gas is 5.00 x 1oam3 mol-1 at273 K and 3.0 Mpa. Calculate:i. Van der Waals constant, .

[5 marks]ii. The compression faclor, Z.

[3 marks]

t.. IJt. '!t-t,

afI

2

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ecB102g I2. a. Nitrogen (Nz) molar heat capacity, c* is constant at 2.s.R fortemperatures in range of 100-400 K. ln a process, 1.02 g of N2

undergoes reversible adiabatic compression at 400 torr from 1000 cmsto 300 cm3. ealculate:i. The heat, q.

[2 marke]ii. The ehange in internal energy, AU.

[5 marks]ii. The work, ry.

[2 marks]iv The ehange of enthalpy, AH.v. The change in entropy, ,5.

[2 markslb. A heat engine is operating between looo K (temperature at hotreservoir) and S00 K (eold sink). Determine:I, The maxlmum efficieney of ths engine.

[2 marks]

. i. The maximum work can be done for each 1.0 kJ of heatsupplied by the hot reservoir.[2 marks]

i. The heat is discharged into cold sink for each 1.0 kJ suppliedby hot reservoir.

[2 marks]

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a..

ccB1023Define the sublimation process.

[2 marks]

i. The enthalpies of vaporization and fusion of water are44820 J mo1-1 and 603 J rnol-1, respectively. The vapourpressure of water at 0"c is 611 pa. calculate the sublimationpressure of ice at 15'C, assuming that the enthalpy changesare independent of temperature.[4 marks]

An ideal solution is made from 4.00 mol of benzene and 2.2s mol oftoluene. At 298 K, the vapour pressure if the pure benzene andtoluene are Pob"n."n" = 96.6 torr and porotr"n" = 2g.9 torr, respectively. lfthe pressure above this solution is reduced to 760 torr. Determine :The mole fraction of each component in the solution.

[4 marks]

Justify your[4 marks]

The enthalpy of vaporization, Af,oo and the boiling point, T6 ofmethanol are35.27 kJ mol-1 and 64.1'c, respectively. Determine:

lt

he entropy of methanol vaporisation.[2 marks]

The entropy change of the surrounding, if vaporization occursreversibly. Justify the heat flow involved in the process.[4 marks]

b

il The pressure when first vapour phase appear.answer.

c.

4

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4. Speetrophotometer is qsed ts measure the composition of a llquid phaseduring the reaction as given below:

2A --" gThe concentration of product B is given in TABLE e4.

TABLE O4 : Concentration of product Bt (min) 0 10 20 30 40 00[BJ (mol dm-") 0 0.089 0,153 0.200 0.230 0.312

a. Write the stoichiometry of the reaction that relates to the product andthe reactant concentrations.[2 markel

b. Determine the concentration of B when the reaction is completed,[2 marks]

c. Calculate each concentration of reactant A with respect to time, andtabulate the data, [6 marks]

d. Determine the order of reaetion. Justify your answer,[6 marksl

e. Calculate the reaction constant for component A, fr,a.[4 marks]

,_)

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5.lII'..t

I:i

ccB1023a. Define the following terms:

Physisorption[2 marks]

il Chemisorpton[2 marks]

iii. Adsorption isotherms.[2 marks]

Describe the Langmuir isotherm and the relationship betweenfractional surface coverage, dwith monolayer volume, v^o,.

[4 marks]A gas at 20"C is adsorbed on the .u#a." of 1.5 g silica atO'C. The volumes of the gas asobeO are 1.6 cm3 at52.4kPa and 27..3 cm3 at 104 kPa, respectivelyr. Detertninethe monolayer volume, vmon. [6 marks]An adsorption of a gas is followed by the Langmuir isothermwith the equilibrium constant, K = 0.777 kPa-1 at 25'C.Calculate the pressure at 0= 0.4.

b.

il

ilt

- END OF PAPER _

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ceB10.?3APPUNDIX

PHYSICAL CONSTANTS AND CONVERSION FACTORSldeal Gas pfopeies of watefPV: nRT Specific heat capacity of liquidMolar heat capaeity at constant pressure, water, Cp: 4.184 J/g-Kcr,,,: ln Specifc heat eapacity of water'2 vapour, Cp: 1.841Jlg-KMolar heat capacity at constant volume, Molar heat capacity of liquid water,Cv,,ri. :R Cp,,,,: 75,312 J/mol-K2corystqnlgMolarheatcapacityofwaterGas constants,.R.' vapour' cp'"|' 33'138 J/mol-K- 83.145 cms bar/K:mol Cqoversion factgr- 82.055 cms atm/K-mot Tff) = tfO) + 2Tg.15- 8.314 J/K-mol 1 atm = 260 torr = 1e1S2S pa- 1.9872 callK-mol 1 bar = 106 dyn/cm = 0.gg6g atmFaraday's constant, F: 96,485 C/mol 1 bar = 750,062 torr = 105 paAvogadro's constant, A: 6.Q22 x 1023 mol-1 1 pa = 1 N/m2Gravitatonal acceleration, g: 980.7 cm/sz 1 cal = 4.1g4Joule1V=1JlThermodynamic formulg l dyn = 1 g-em/szAH=AU+PAV atconstantP l dyn/cm= l erg/cm2-10-3 Jlm2U-q+w lerg=10-7J,u=-lpdv l lnch =2.4emJ 1=10-8em=0.1 nmAH=gp= [crar l liter= l dma= looocma

A(J = v = lcrar Qfhcr Eo"qationg^r,-rev Arrhgnius: A=ee-k-L) -+- T Langmuir isotherm: c = qf_1+ KpBET lsotherm:P 1 e-1 Pve-n=W-q-c'F