RELIMINA RY Mu wise LTIP Preraratio N LE CHoice QUESTIONS CEN EEEEaeES 41 INTRODUCTION (THERMODYNamtcs, TTS SCOPE AND LIMITATIONS) . 1. The information not conveyed by thermodynamics is about (@) spontaneity of a reaction(b) yields of t the products formed (©) sates of reactions (A) all the thee above 42. THERMODYNAMIC STATE (SOME TERMS AND CONCEPTS USED IN THERMODYNAMICS) 42.1 Open, closed and isolated systems 1. Plans and tres constitute (@) an open system ©) a closed system (©) an isolated system (@) none of these 2. Itwis the amount of work done by the system and qi the amount of heat supplied tothe system, identity the typeof the system (2) isolated system @) closed system (6) open system (d) system with thermally conducting walls (NCERT Based; AMU Med, 2010) 3. A system which can exchange energy with the surroundings but ‘no matter is called (@) abeterogencous system (b) an open system (©) closed system (@) an isolated system 4. A well stoppered thermos flask contains some ice cubes. This is a example of @ (a) closed system (©) open system (6) isolated system (@ non-thermodynamie system 5. Am isolated system is that system in which (a) there is no exchange of energy with the surroundings (>) there is exchange of mass and energy with the suroundings (6) there is no exchange of mass and energy with the surroundings (4) there is exchange of mass with surroundings Which of the following is a closed system ? OG ea psd inal te (©) Pressure cooker (a) Rocket engine during propulsion 422. State function and path function ital state to te Final state were 2 i tages in a sytem from am inl tae 1 he Ot (b) AM isa state function and ¢ isa path function (6) both AH and q ae state functions (@) both AH and g are path functions 8. Which ofthe following statements is correct? (@ Internal energy is a state function but work is not (©) Work isa state function but internal energy is not (©) Both internal energy and work are state Functions (@) Neither intemal energy nor work isa state funetion 9. Which of the following isnot an exact differential ? @ a (©) dg + aw (© dart @ aw 10. Which of the following isa path function ? (@) intemal energy (©) enthalpy (©) work (@ entropy (MH CET 2007) 4.2.3 Intensive and extensive properties 1 In which one of the following ses, all the properties belong to same category (all extensive or all intensive) ? (@) Mass, volume, pressure (6) Temperature, pressure, volume (©) Heat capacity, density, entropy (@) Eathalpy, internal energy, volume 12, Which of the following isan intensive property of the system? (@) Total mass (6) Total energy (©) Volume @ Energy mot! (AMU Med, 2013) 12, An intensive propery in themadynamics teams a po which depends ad (2) on the amount of the substance only (&) on the nature of the substance only (©) both on the amount as well as nature of the substance (@) neither on the amount or on the nature 414, Which among the following is an extensive property of the system ? (a) Temperature (©) Volume (©) Refractive index @ Viscosity 15. Among the quantities, density (p), temperature (1), enthalpy (H), heat capacity (C,), volume (V) and pressure (P), a Set of intensive variables are ‘made by a different manner that (a) (p.T, H) ©) (Tv) -ause ( MTC) ( (TP) (KVPY 2011, 2012) () AH is a path function but q is a state function on goa se Lie tne OO Sa) EEGs Le ¥ 1S. Bb 1b me oa(AFMC 2004) wing statements is incorrect about inter value of internal energy cannot be determine me mole ofa substances same at ay at change during reaction by ermal energy change oe property, (a) Internal energy is an ex 3. The internal energy of a substance (a) increases with increase of temperature : decreases with increase of temperature (@) FHS and E° are extensive, Vy is intensive (ISAT 2012) a 42.4 Types of processes (reversible, (@) can be calculated by the armen, irreversible, isothermal, adiabatic, cyclic etc.) 2” Dating tema expo of ne 8 ne ay 19. The four curves A,, Az. Ay and A, are sh ae Az As and Ay are shown on p-V diagram, ‘Which of these curves represents adiabatic process ? may increase or decrease remains unchanged | ee a i and returns to state A by an ireversible path, what would be the > “ p net change in internal energy ? : ‘4s : @ >40K ©) <40K0 © 2210 @ 400 (AIEEE 2003) rv 4.2.6 Caleulation of work done (reversible and irreversible) (@) A; () Ay in isothermal expansion of ideal gases Ay A, (Manipat 2013) 96° tHe work f . The work done during the expansion of a gas from a volume of 20. Which equation is correct for adiabatic process 4dm* to 6 dm? against a constant extemal pressure of 3 am is (@) O=+W ® ag=0 atm = 101-32 ki) (©) sE=0 @ p+av=0 -65 (b) 608 (©) +3083 (@ - 3043 (AIPMT 204) 30. Three moles of an ideal gas are expanded spontaneously isto vacuum, The work done will be (8) 3 joules (@) zero (AIPMT Mains 2010) 31, 2L of an ideal gas at a pressure of 10 atm expands isothermally into vacuum until its total volume is 10 L. How much wotk is (©) the surroundings are always in (d) the system changes into surrouridings spontaneous (Chd, PMT 2009) an isothermal process done inthe expans q=OandAE=0 — (b) q#0and AE =0 (@) 8am (©) 161 Lm (©) q=0andaE#0 — (d) g#0and AE 20 () 240 Lam (@) No work is done (MP PET 2006) (auiMs 2018) 4.2.5 Work, heat and internal energy 23. Whien one is true ? (a) 1 calorie > 1 erg > | Joule () Lerg> 1 calorie > 1 Joule (©) Lealorie > 1 Joule > | erg (@ 1 Joule > 1 calorie > 1 erg, smal expansion of one mole of an ideal S744. (@ 625723 (AuIMS 201) ‘of an ideal gas expands isothermally at 37°C frm (0 25 lites, the maximum work obtained is 2.871 () 6435 B71 (a) 2925 (ARMC 2010) Wa 20.6 e226 We | haaa 40,47 #0,wao 49=0,aT =0,weg 300 K against a work done is © 10% (@) ~ 62005 © ~ 3063 © -31005 @ ~ 15505 38. A Bs expands isothermally and reversibly The Work done by the ©) Maximum (@ Cannot be determined ible expansion of one mole of 5 t0 20 lites at 25°C is (©) Minimum 39. The work done in ergs for the ‘an ideal gas from a volume (@) 2303 x 298 x 0.082 og 2 () 298 107 x 8.31 x 2.303 log 2 (©) 2.303 x 298 x 0.082 log 05 (4) 2:303 x 298 x2 log 2 40. A gas can expand from 100 ml to 250 ml under a constant Pressure of 2 atm. The work done by the gas is (@) 3038 Joule () 25 Joule (© Skéloule @ 16 Joule 41. 4 Latm is equal (@) 4050 cl (©) 7875 cal (© 9523 cal (@) %6 cal 1010) 42. The work done when wo moles of an ideal compressed from a volume of 5 cm? to 1 dm? at 300 K under a pressure of 100 kPa is (@) 499.9 5 () ~ 49991 (@) 42495 ks le of an ideal gas at 300 K is expanded ume of I L to 10 L. The AF for the proc ( 1 cal (@ 9Lam ¢ ‘44. ‘The pressure of a gas is 100 kPa. If itis compressed from 1 m? to 10 dm}, find the work done (a) 9905 (6) 99903 (©) 99003 (d) 99000 J (MH CET 2010) img 8 aT i Sree er ar sh ae an7 45. An ideal gas expands in volume from 1 x 10-3 to 1 x 102 m3 at 300 K against constant pressure of I x 10° Nm™?. The work done ) 9003 (©) 270 (®) ~ 90015 (d) 900 ky y 2 46. 16 g of oxygen gas expands isothermally and reversibly at 300 K 10 dm to 100 dm. The work done is in J) 28753 47. At the same conditions of press work done is maximum for whit () ~ 28755 infinite MH CET 2 ‘lume and temperature h gas if all gases have equal xa oo Some beset li 500 st 200 Pa pene a EES ete exne © oxsoen CL in joules during reversible 1€ MUS be expressed in "8 isothermal expansion of one mol {o 1 atm. at 300 K is © 413881 @ 025725 S05 expand isothermally and reversibly from a tata eso, 8 Youme of 10 lites at 2%. What se @) 47g £25 from 10 atm a PYACBP.P, () ACBB,ALA ACBDA (@) ADBB,A\A leulate the work done when | mole of an ideal gas is compressed reversibly from 1.0 bar to 400 bar at constant temperature of 300K (a) 34610, © ~ 82010 fc) 180213 @ - 14018 4d a 3b Md aheat from the 29° rb 2 bea 8 te Con ae me in one cycle ig "ie The amount of weal (2) 04 keat @ae © 08 kea @ Star 4.3 FIRST LAW oF THERMODYNAMIcg AND TTS APPLICATIONS 1. Which of the following Oq+w Wq an @ (and ay) (© ©, QW) and a) w (V) HTS (©) QD, (Mp ana ayy @ (Wan amy 56.6 She 58) MSEN ot tw 4 MCQs in Chemistry twp, 2 Prati alg is ine a oan (a) 1U=We0,g=0 (0) AU=0,W=q40 with a ey B is () AU=W=qa9 @w mes AU = 429 ‘AIPM a J stew 9” QQ He absorbs heat Qy at temperature » peat Ty Wok tone ote engine is 5 2 aaa 1odynamics ay (@) violates 1st law of therm ©) Niles I law of thermodyoamics if 2, is yy (© silts a law of thermodynamics iQ ig vo (@) doesnot violate Ist aw of thermodynaric, 4. AB is always positive when (@) sytem absorbs heat and work is done on it work is done on it 5. A piston filled with 0 from $00 mL 10375 oes $0, it absorbs Process will be (R an ideal gas ex, 100 A COnstant temperatan? 7207, of heat. The value or 24S reve 37904 314 Ymol. n7-5 = 9-915 Ast 4 208 w fey ‘ork is done onthe (Kerala PMT 28) 2 constant pressure of '8 in internal enegy 89,[THERMODYNAMICS AND ENERGETICS 13. ~ Tie mole fame at expan eerily ue tera une Vi 2 0K. The amount of heat cage @o 0) 72 Ot “ ‘ a @ 172 (KVPY 2012) Ln 58, work is done al the expense of in (9 ete (c) adiat © abatic: (@) isobaric (MH CBT 2009) 1S. A ga expands isthemaly aginst a conan extemal presure in from a lume of 10 dn to a vole of 20 dn? I absorbs 800 J of thermal energy from is surroundings. The AU is (@) - 312) +135 (© -2135 @ +231) (Bihar CECE 2007 16, The volume of a gas decreases from 500 cc to 300 ce when a sample gas is compressed by an average pressure of 06 atm. During this process, 10 J of heat is liberated. The change in internal energy is (@ -2163 () 121561 = © 2163 @ 1013) (BHU 2006) 17, One mole ofan ideal gus isiniially at °C and 1 stm pressure. I it absorbs 1000 cal het during reversible isothermal expansion, what willbe its final volume ? @ 12st, © ms5L Oz @ m125L (Glaryana PMT 2008) 18, At27°C, one mole ofan ideal gas is compressed isothermally and reversibly from a pressure of 2 atm to 10 atm. The values of AE and gare R= 2) (@ 0,- 965:84 cal (6) ~965 84 cal, + 965:84 cal (6) + 86558 cal, - 86558 cal (@) ~ 86558 cal, ~ 86558 cal (BHU 2001) 19. The work done by 2 system is 8 joule, when 40 joule best Sopplied to it What i the increase in intra energy of sem @ 353 @ 303 © 2! @ 2 cay 200 w contract a gas in a cylinder, is 462 joules, 2 Th wah Cedi pss Wt wl Be Jneral energy change i the proces ? (a) + 590 joules (b) ~334 jules ; (o) +334 joules (a) ~$90 joules (MP PME 2008 a Oe mole of an idea gas 300 Kis expended sobama [0 ora ylume of 1 ie 010 ire. The AE for hs Poses (R=2cal Kt mot!) (a) 1637 cal () 1381-4 eal (e) 9 litre-aum @ 20 creases by the same intemal energy of an ideal gas decreases bY 2a es the work done bythe system the process (6) isothermal (a) cyclic eee So cnt toe ine 101 aeons 250 feat and expands fom 1 iret 10 ie at 25, Ae aaa 2p eral pes of 05a Te cage of 9, wand AU wil Be respectively. ge We Wee Id the Be te td de 4b Sb be ome ang (a) 25015455 5,105 (6) 2501, ~455 3,~2053 (€) = 2505, ~455J,~ 2055 (dy ~ 250 J, 455 J, 205 J 24, A gasis allowed to expand in a well insulted container against a constant extemal pressure of 2:5 atm fom an initial volume of 2:50 L to final volume of 450 L. The change in internal energy ‘AU ofthe gas in joules wil be (@ 1136255 () - 5005, (9 - 5053 (d +5055 4.4. ENTHALPY CHANGE AND ITS RELATIONSHIP WITH INTERNAL ENERGY CHANGE 4.4.1 Based on the basic concept of internal energy and enthalp: 1. During isothermal expansion of an ideal ga, is (internal energy increases (@) enthalpy decreases (©) enthalpy remains unaffected (enthalpy reduces to zero. 2 Water is supercooled to - 4°C. The enthalpy (H) is () same as that of ie at - °C (6) more than that of ice at - °C (6) same as that of ie at °C (@) Hess than that of ie at °C 3. Under which of the following condition {BH = AE + PAV valid fr a closed system? (@) Constant pressure (@) Constant temperate (©) Constant temperature and pressure (@) Constant temperature, pressure and composition (WB JEE 2009) is the relation 4. During the evaporation of a liquid (@) the enthalpy decreases (@) the enthalpy increases (6) the enbalpy remains unchanged (a) the internal energy decreases ' Which ofthe following isnot correct about enthalpy ? (q) It isan extensive property () tis nota sae function (6) Its absolute value cannot be determined (@ Enthalpy of a compound = Enthalpy of formati ‘compound 6, For the isothermal reversible expansion of an ideal gas (@) SH > Oand AU (b) AH>Oand AU <0 (o) AH=0and AU=0 — (d) AH=Oand AU>0 jon of that ‘The heat change at constant volume (q,) is equal to (@) au () aH (©) RT (0G ‘One mole ofa gas absorbs 300 J of heat at constant volume and i temperature is raised from 30 to 35°C. The value of AU is (@) 150 joule (6) 01 joule (©) 300 joule (6) 200 joule Me Wd Me BH we te OES4n0 a ommen m a7C evita nts oem te oe Salat aan ena west mn mem ty ih Mog bla an ae sl a (e) a cau 10) therein relation avs au (@ a= au 12, An endothermic reaction has «postive itera enerey change S30. Tp mc cases what ithe minim valve that action fea) can have @ au) () sU = atts ok (© aU=aH-aakT — (@) AU=E,+RT 13, A mixture of tro moles of carton monoxide and one mole of ‘Soyen in lord verte i igited a convert carbon monoxide to SiR onde, AN the enhaly change and AE ithe chang {e ieal energy hen (a) a> aE () aH (@) (6) PC, (g) + PCL fe) Ch (> ) 2€0 Ux) +03) > 2 C032) Anis 2014) 18, Standard enlpy of vaporistion By HT for water at 100° is #1066 1 sol! The itera energy Change of vaporistion of Sete at 1 fin me) (ay 3756 6376 +676 (6 + 4066 (AIP MF Pest 2012) 16, Forte reson C,H (g) +5 04g) —+ 3 C03 (#) + 4130 0 constant temperature, AH = AU is @ +m 3K ( +3Rr ® -er i 17, The enthalpy change (AH) forthe reaction Nps) +3 Gg) —+ 2H) 1-92.36 298 K. The intra energy change AU a 298 K (@ ~92360 ) -#742 10) © 9340 (d) 89953 (nips 2006) 1M. Te eras betwen tet fren a ont prem nd 24H + 15.03 @)—+ 12.C05 (4) + 10.0) s28cinw is 2b We Me eb Me me BE ME wb (ay 78 for the combustion of ait and BE f jn joules nega 30 2) ay BBVA 3000) fo -¥ oth ace tween " ‘methane at 27°C will Be mega a xe) (nat 300 « 2) em : . (oy 5827 mst sie, NICH 09 20, The reaction of te and AU wat fund Be 7427 Pca tina bomb ca emi cange Fe ration a 278 Ka a 141-5 kS mol! etm) ALS Oot mer! 6 old benzoic acid a constant vole the heat of cmon of so on a is - 321-30 kJ at 27°C, The heat ‘of combust fro — ty zat 300 R (22130 = 108 () — 32130 +300 8 (d) ~ 32130 + 900 R Kind tam he ate eat of vapor of gd a 30 22, The he cal hot wl be the change ra Fi oe ete Id the same temperate a () 270 Kea (@) 130 keal 4 ( =270 kal (d) ~ 130 keal 23. tn which one ofthe fllowing eases, AH and AU are not equal (e) The reaction involves no gaseous reactant or product (@) The number of males of gaseous reactants and gum ‘product isnot equal wo each other (The number of miles of gascous reactants and pcan products is equal teach other (a) The proces is cari out i a closed vessel I. At constant T and P, which one of the following matemeas s entet for the reaction Sy (0) + 8 O3 (g) —> # $0; @)”™ (@) ane au ©) a= au (eo) an> au. (AH is independent ofthe physical sae ofthe reactant 25, The heat of combustion of carbon is — 94 Keal at 1 atm pre=u the intrinsic enersy of CO, is (@) +94 kcal () ~98 keat (+47 beat (@ ~ a7 cat 26, Given the reaction 240 K and 1 atm. €3C0 (9) —+ C10 (8) +03 (8) AH = 176 kuimol, the AU equals (@) 16004 ©) 16560 fo) 16-4 Ww 180.0% 27, For the reaction, A 7 tion. A (8)-+ 3 Bg) 4 C (4) + and A ire related ax : pee @ an = au () aH au 63 RT fo an Wo aH =au-3RT Bab, ee bo he ie 20d @ ~3740 (©) ~ 37647 34. Assume c3c ‘whieh react (@) POs © 2006 (©) H+ @ cw+ 35. The heat of. ‘The intrinsic (a) +94 ke ©) +47 ks 36. The combus hat beat of Wd mot ae ‘constant pe @ 1526 © 32350 Based « coneepi 37 Joute-Thom (@) isobaric (©) isother 38. For an idea 2b a9 Gs |.“— gRMODYNAMICS AND ENERGETICS pH! ans cat x vpn ofa iid is 20 too. Amaning eal —) A= 2b Te a fox arene eral ene forevaporiaionel alco (aso Poo ofthe liquid at 60°C and 1 bar is close to oa 72 39. Study the following data Ai) for the following By — Hp + Hy = my RT ~m RT : =n, RT RT RT- 7 RT (@ ¥y—Hy Ey By =m RT-m RT ™ 40, AE* for the combustion of isobutylene is —X Km of AH? is @ =a >aE @ <4E ‘During an isothermal expansion of an ideal gas its ral energy increases Enthalpy decreases Enthalpy remains unaffected Enthalpy reduces to zero 2 of graphite is completely burt in a bomb calorimeter in ‘excess of oxygen at 298 K and | atmospheric pressure. During the reaction, temperature rose frot capacity of the bomb calorimeter Change for the combustion of graphite at 298 K and I atm is (@) ~ 124210 mor! 2 (a) ~ 207 KI mot! 238, For the reaction CH,COOH ( + 2.0, (4) = 2.CO, (g) + 2 HO (0 at 28°C fand 1 atm, pressure, AH =~ 874 kJ. Then the change in intemal () - 87153 (© -8764710 @ +8740 4, Aosume each reaetion is caried out in an open container. FOr 4 ‘The amount of heat measured for 8 eaton ina bomb clrimeter is ‘which reaction will AH = AE. naa an j@+a AE @ Pav (@) +94 keal () ~ 94 keal 1. The molar heat capacity of (©) +47 kcal @ ~ 47 keal 36, The combustion of benzene (D gives CO that heat of combustion of benzene at kd mol"! at 25°C, heat of combustor constant pressure will be (R = 8314 J gas a constant temperate and presse 3 s @ 3R 3 az 2 (©) depends upon atomicity of a (@) infinity () 2. Molar eat capacity of a () diatomic (a) wiatomic (@) monostomic * an ideal gas expanding adiabatically in vacuum (6) polyatomic Pa os Ty Ed She Me Be Me 355 Sed dD Be ME Mad 2e (3d (de ERM 1b (2a 30 4 mma “4. Consider the following statements: For diatomic gas, the ratio CJC, is equal to 1. 1.40 (lower temperature) 2. 1466 (moderate temperature) 3. 1.29 ¢higher temperature) Which of the following statements are correct? (@) 1,2and3 () Vand 2 (©) 2and3 (@) Vand 3 . The ratio of y for inert gases is (@) 133 ) 166 ©) 24 @ 199 - Ratio of C, and C, of a gas is 1-4. The number of atoms ofthe gas °X” present in 11-2 litre of it at STP is (@ 602x108 @) 12x 10% (©) 301x108 (@ 201 x 108 The rae of te Het aes Gy, for one moe of 1-67. The gas is a (@) He on © ©, oH (KVPY 2009) of mixture of gases 8. Equal volumes of two monoatomic gases, A and B, at same temperature and pressure are mixed. The ratio of specific heats (CJC) of the mixture will be: @ 33 ®) 167 © 083 @ 150 1 mole of an ideal monoatomic gas is mixed with 1 mole of an ‘deal diatomic gas. The molar specific heat of the mixture at constant volume is (@) 3eal © Seal © 8al @ Seal 10, Equal volumes of monoatomic and diatomic gases at same initial temperature and pressure are mixed. The ratio of specific heats of the mixture (C,/C,) will be AIPMT Mains 201 @1 2 © 167 @ 1s APMC 2002) on the relation G,~ G, = R 11. How many calories are required to heat 40 gram of argon from 40 to 100°C at constant volume? (R = 2 cal/mol K) (@ 120 (®) 2400 (© 1200 @ 180 12. One mole of an ideal gas for which C, 3 SR is heated 2 reversibly at a constant pressure of | atm from 25°C to 100°C. The AW is (@) 3-775 cat (b) 37-256 cal (©) 37256 eal (d) 372556 cal 13. C, values for monoatomic and diatomic gases spectively are (a 3R, 5, @ ) FR 5R () 3e3 © FR GR Sb 6a 2a kb ind Ba a Ae 2b YY ___ Pradecp’s MCQs in Chemistry [NEET] 14. 4448 L of an ideal gas at S-TP. requires 12 calories to rise i temperature by 15°C at constant volume. The C, of the gas is (a) Scat () 4cal © Teal (a) 6 cal (@) cal 18, For hydrogen gas C, ~C, telation between a and b is (a) a=16b () a=b (© a=4b CO) 4.6.5 Calculation of W, QU, AH and Q in adiabatic expansion ‘and for oxygen gas C, ~C, 16. An adiabatic expansion of an ideal gas always has (a) decrease in temperature (6) q=0 (w=0 (@) a MP PMT 2003 For isothermal expansion of an ideal gas, the correct combination of the thermodynamic parameters will be (@) AU =0,Q=0,w #0 and AH +0 (© AU #0,Q=0,w 40nd aH (©) AU=0,Q40,w=0,AH #0 (@ AU =0,Q40, w#0 and AH. 18, One mole of an ideal gas is allowed to expand reversibly and adiabatically from a temperature of 27°C. Ifthe work done dung the process is 31, the final temperature will be equal to (C, JK) (@ 150K @® 100K (© 2685K @ 295K 19. When an ideal gas is compressed adiabatically and reversibly, he final temperature is (a) higher than the intial temperature (®) tower than the initial temperature (©) same as the initial temperature (@) dependent upon the rate of compression 4.6.6 Based on the calculation of q from q mxexat 20. If one gram of kerosene liberates 460 KJ of heat on burning © ‘what temperature will 0-50 g of kerosene raise the temperate of 100 cm? of water at 25°C ? @ 4c & 6c © sc @ 108 21, How much energy must be supplied to change 36 g of ice at PC water at room temperature 25°C ? Data for water A oe 601 ki/mol Cea 418 Kg @ Du ®) 16K © 9 @ 2w 22, Anice ce at 000°C is placed in 200g of distilled water #25 ‘The final temperature after the ice is completely melted is What is the mass of the ice cube ? (aly, = 40d eC, = 418 gC) @ Be ©) 4638 (©) 500g @ 8008 9b 10d Wed he 186 hd SE 2ba [THERMODYNAMICS AND ENERGETICS _ “67, Based on the relationship between RV and T in adiabatic expans Ce ee ee ca Rh q, Aq aye BL a (a) all are correct 23. Ad Base: “The enthalpy of a monoatomic gas at T Kelvin is 3 (SRT wo Set z 25, How many grams of ice at (FC can be melted by the addition of Ehoy ot eat The molar heat of fusion for ice is 602 KY mot") (@) 00831 ¢ @) 1508 fo) 3018 (@ 120g | (DUMET 2010) 26, SC, forthe change Na (g) +3 Hy (8) = 2 NHs (8) 8 )— ® 2Wyyas, ~ Cyn, +3Cput,? @) Cyyai, Cp ©) 2C pneu, —(Cpn,)— 2Cprat * Cp, #3C pH) 47 EXOTHERMIC AND ENDOTHERMI cTIONS 1. Look a the following diagram: | | z] 4 z 2 | Progress of Reaction ——— The enthalpy change for the reaction A —+ B will be ) -25 ) -40w aoe (a) 6543, Wii of he folowing reaction do you think wil seul in the eorpion of heat? (4) Carton burning in wir (6) trom reacting with sulphur w form (©) Formation of water yas trom steam and coke a sulphide (4) Formation of prod oe lacer yas Wansition Cidamend) —? Lalowr aa Ciaments —* Casati | AH 15 Kb w diamond is exothermic (b) graphite is endothermic Be was, ag hee mee sr + —l (0) raphe 6 stabler than diamond (A) diamond ie stable than eraphite 4. For an enuethermi fe rection where AA represent the rection tr Klik we ae af rorenet the ental of setivation will be alue for the energy of (a) ess than AM (©) more than AM ne ae oe ieee eee Cae cee (ace | eee (CH, (4) +203 (4) —+ CO, (¢) + 2140 (a), AH =— 3904 Gate amiaeceeerrmes pepe eee a eee rere (a) endothermic (6) exothermic 0 a went 2 rr aw octet dy soe oa ieae a pias a (c) remains same (d) cannot be predicted ee ae ae a i oper emi © re a cee eae rena tems (a) CaCOy —> C0 + SO Ce (c) NaOH + HC! — NaCl + H,0- (@) CH, +20, —> CO; +7 #20 All reactions with chemical dissocat (Beever 10, u joa ae (@) reversible Ye and enothermi= (©) exothermic (a) eeversible or irevers Which one of the following i a0 €*° (a) boiling water to stea (®) cracking heavy petroleum esi {e) conversion of white phosphorus (0d phosphoes (a etecuobyin of ise sium BOOS se 13. The hypothetical gaseous reaction A +B (@) Exothermic (8), Endowerais (©) Does not involve enthalpy change (@ Cannot be predicted Se Rae Fe ce ‘ble and endothermi of exedherm i whermic Feae000For the renctim. > 0, MSE = anew ee {ees star the expen wnt forming onypen adie Wie © « AN 6 We etary of rete and for Afi, cama of yeast tee «an, > a bat =, ah as 4) aM + aH, <0. Te camp) oF tome of amas 460 AS mol comnaips taupe tos tr easton 2 NH ig) + 2% 12) et at 200 et iyi supe. 3178 feat we evines Nhe Oth tos tae oie he we ass ou so cay sme Ancompnes yen reathy forms The 1) + Hyp) 6M supper asc aod 20 J ob Praddeap's MOOS in Chemistry (NEETIF] wo) wn osu The ation aicinecattion of Neat of a. renction with eet ngtion Ga HOT ster ‘yw rt rears uh Hees Ine 4. The hea af comfoetinn oF 4 eaetion foes a depend on Plea atte ofthe tte A) Temperstine st hich combustion is cari nt ao Wf oeyiten present 4) Whether the so owed veel fon is cated owt i an open Yess y 7 The cihaly change for the resetion 2 Hi Gg) #0. HUQ) AH = 872 RF The enthaliy of formation of artery ay ete (my 7 erst) 86 eH The heat of formation of HO (2) 6 286 1, The heat of formation of HO 44) 6 likely 0 be i a,” 2 0R | T, Oy ph = tHe (BT 7 1 The standacd eat of formation of diamond is (4) samme ao tha of grapite (5) rear thas that oO apa 6) Ne a tha OF gape) ae a6 ex Which of these species as a standard _ maa caunalpy 04 corm ual wo ue nme Ww Fa) 1 HE Cay) Sime te cuihalpy of slements in ter aalural ste saben 460, the Heal vk turwaion (3, H) of compounss 4) bs abways uegaive (by la always positive (le) May be ueyanve ut positive 8) to acu wy Fu Ww) Fay sd duke Sa he dk— suerMODYNAMICS AND ENERGETICS p \AMIGS AND ENERG aN 4? 2NO(e) + 02 pe enthalpy of formation of @ @x-2Y 03 (g) 9 2NOp+ XI (g) —2 2 Op (@) + Y KY NO is xy 1 wm 5%) oso : vations 6 Ac 81 rox which one of the Following ea ‘Sue for the prt 7 Ns tg) # 04 ()—F N29 0) cata te) #2 Ch (€) —4 CHAR (0 #2 HET fo Ne te) #2 Fr (a) —# NEF (8) 20 (@) +03 (g) —> 2 C02 (8) (AIPM 2003) @ ssonaard enthalpies of formation of Oy, COp. NHy and HE are © Saga go7 3, 46:2 and + 25.9 KI mot ! respectively. The order atthe increasing stabilities will be fe) Ox. COs, NHs. HT (#) CO3, NHy, HI, Os 1) OL HLNH,,CO, NH, HI, CO,, Os. L +0; —* 05, AH == xs COF 5 0; —> CO; AH == y ‘Then AH, for CO will be (a) 2x+y () x-y (oye? y-* ‘& Consider the following reactions BY (ag) + OH (ag) = HO (0, AH =~ X, WJ mor! (PMT 2002) H,0 (0, AH = ~ X; kJ mot! 1 Ww Hz @)+ 5 OW i) CO, (g) + Hy (g) = CO (g) + H,0 () ~ Xy HI mol! 2.00, (g) + H,0 (D+ X, kJ mor 5 is) Cg) + F O26) Exthalpy of formation of HO (0) is @ +X, mor? (6) ~X; kd mor! © +X) 0 mot (é) X13 mot (AIPM 2007) 9 The standard cothalpy of formation of NH, (g) is ~ 91-8 KJ mol The amount of eal required to decompose 34 g of NH, (g) into sts elements is @ 160 ) 98 KS fo 4595 @ BIT eo 275.44 (Kerala PME 2015) 10. Te hea of combustion vf carbon w C03 is ~393:5 kI/mol. The teat released upon formation of 35:2 g of CO, from carbon and en too ass cide) (d) +315) Un) Pap snemical energetics impli te, | sre 273 Kb) 1am presi at 298 K at Pressure at 208 K n@! ‘Prenat specified temperature ron Inoe of H,0, is decomposed by platinum black, the heat Co) oe oe MT Heat of fommation of 1 ole of #0, ir ) 1932 id) 48:31 16. 18. 1. 20. 2. 23. |. For which one ofthe following elements dhe standart enthalpy 1s (a) © (iano 18) © (Graphite (A) Rhombe sulphur Heat of formation, Hof an explosive componnd like NCI, (a) positive (6) neeative : (6) rer0 (positive or negative ‘Which of the following reaction can h formation of CO, (a) ? awed 10 define the heat of (a) C (graphite) + 03 (2) —s COn(@) (b) CHy (2) + Og (2) —» CO, (a) #2 HAO 1 (0) €O(R)+ 4 05 (@) C041 (0 Cas 0+ 74 Opt) —+ 8500440) #3 14010 Which of the following values of heat of formation indicates that the product is least stable (a) ~ 94 keal (@) ~ 2316 keal (6) + 21-4 keal (d) +648 kal Which of the following equations correctly represents the standard heat of formation (4y H”) of methane ” (a) C (diamond) + 2 Hy (s) = CH, (8) (b) C (graphite) +2 Hy (g) = CH, (0 (©) € (araphite) + 2 Hy (g) = CHy (a) (@ C (graphite) + 4 = CH, (®) “The compound with negative heat of formation is known as (@) endothermic compound (b) exothermic compound (©) endoergonic compound () aone of the above Hi + Cly —> 2 HCl, aH = ~ 194 Xd, In this reaction. beat of formation of HCI in KI is @ +1940 +97 (© -9T (@ - 194 Enthalpy of formation of compound is (a) always positive (always neganve (c) cam be either negative or 2er0 (d) can be positive or negative The enthalpy of formation of two compounds X and ¥ are = 308 ‘and - 72 KJ respectively. Which one of the following statements is comrect ? (a) Compound X is more stable than compound Y () Compound Y is more stable than compound (©) Both compound X and are endothermic compouns G@ Both X and Y are unstable (COMED K-UGET 2011) 2. Enthalpy of a compound is equal © its (6) heat of formation (a) heat of combustion (Ud) eat of solution (©) eat of reaction, (©) eat of dilution “The heat of formation is the change it formation of a substance from its elements of pressure. Since the enthalpies of elements ae the heat of Formation (AH) af compounds (a) Is always negative (6) Is always posinve (©) May be negative or positive ae ee otalpy accompanying 28 K and | aun taken 9 e 210 (Karnataka CET 1993)