4131 + Interview Questions in THERMODYNAMICS IN GENERAL AWARENESS Page 7 InterviewSolution

301.	The difference in `DeltaH` and `DeltaE` for the combustion of ethane at `27^(@)C` would beA. `Delta H gt Delta E`B. `Delta H lt Delta E`C. `Delta H=Delta E`D. No relation
Answer» Correct Answer - B

Discussion

302.	For is reaction involving only liquid reactants & liquid products the relationship between `DeltaH` and `DeltaE` isA. `Delta H gt Delta E`B. `Delta H lt Delta E`C. `Delta H=Delta E`D. `Delta E ge Delta H`
Answer» Correct Answer - C

Discussion

303.	`DeltaH gt DeltaE` for the reactionA. `CH_(4)(g)+2O_(2)(g) rarr CO_(2)(g) +2H_(2)O(g)`B. `N_(2)(g)+3H_(2)(g) rarr 2NH_(3) (g)`C. `C_(2)H_(4)(g) +3O_(2)(g) rarr 2CO_(2)(g) +2H_(2)O(g)`D. `CaCO_(3)(s) rarr CaO(s) +CO_(2)(g)`
Answer» Correct Answer - D

Discussion

304.	For which of the following reactions `DeltaH=DeltaE+2RT`A. `N_(2)(g)+3H_(2)(g) rarr 2NH_(3)(g)`B. `N_(2)(g)+O_(2)(g) rarr 2NO(g)`C. `NH_(4)HS(s) rarr NH_(3)(g)+H_(2)S(g)`D. `PCl_(5)(g) rarr PCl_(3)(g)+Cl_(2)(g)`
Answer» Correct Answer - C

Discussion

305.	For the reaction `A rarr B,DeltaH = + 24 kJ //`mole For the reaction `B rarrC , DeltaH= -18 kJ `// mole . The decreasing order of enthalpy of A,B,C follows the order `:`A. A,B,CB. B,C,AC. C,B,AD. C,A,B
Answer» Correct Answer - B `A rarr B, Delta H = +ve` means that `H (A) lt H(B)` `B rarr C, DeltaH = -ve` means that `H(B) gt H(C ) ` or `H(C ) lt H(B)` Adding the given equations,we get `A rarrC, DeltaH = + 6 kJ mol^(-1)`. This means that `H(A) lt H(C )` Combining the above results. `H(A) lt H (C ) lt H(B)` or `H( B) gt H( C) gt H(A)` . Hence, decreasing order of enthalpy is B,C,A.

Discussion

306.	For the complete combustion of ethanol, `C_(2)H_(5)OH(l)+3O_(2)(g) rarr 2CO_(2)(g)+3H_(2)O(l)` the amount of heat produced, as measured in bomb calorimeter, is1364.47 kJ `mol^(-1)` at`25^(@)C`. Assuming idealty the enthalpy of combustion , `Delta_(c) H`, for the reaction will be `( R = 8.314JK^(-1) mol^(-1))`A. `-1350.50 kJ mol^(-1)`B. `- 1366.95kJ mol^(-1)`C. `-1361.95kJ mol^(-1)`D. `-1460 .50 kJ mol^(-1)`
Answer» Correct Answer - B Given `DeltaU = - 1364.47 kJ mol^(-1)` `Deltan_(g) = ( n_(p) -n_(r))_("gaseous") = 2-3= -1` `T = 25 +273= 198 K` `DeltaH = DeltaU + Deltan_(g) RT` `= - 1364.47kJ + ( -1)` `( 8.314 xx 10^(-3) kJ K^(-1) mol^(-1))( 298K)` `= - 1364 .47 - 1 xx 8.314 xx 10^(-3) xx 298K` `= - 1364.47 -2477.57 xx 10^(-3)` `= - 1364.47 - 2.477 = - 1366.95kJ mol^(-1)`

Discussion

307.	`DeltaG` is a thermodynamic prop erty the decrease in which value is the measure of useful work done at constant temperature and pressure: `DeltaG_("system") lt 0` (spon tan eous) , `DeltaG_("system")=0` (equilibrium), `DeltaG_("system") gt 0` (non- spon tan eous), Free energy is related to the equilibrium constant, as `DeltaG^(@)=-2.0303 RT log_(10) K_(c)` A reaction has poaitive values of `DeltaH` and `DeltaS` from this you can deduce that the reaction:A. Must be spotaneous at any temperatureB. Cannot be spontaneous at any temperatureC. Will be spontaneous only at low temperatureD. Will be spontaneous only at high temperature
Answer» Correct Answer - D

Discussion

308.	For the reaction `2Cl(g) rarr Cl_(2)(g)`, what are the signs of `DeltaH` and `DeltaS`?
Answer» Correct Answer - `DeltaH` is negative (bond energy is released ) and `DeltaS` is negative (There is less randomness among the molecules than among the atoms ) `DeltaH and DeltaS` are negative The given reaction represents the formation of chlorine molecule from chlorine atoms. Here, bond formation is taking place. Therefore, energy is being released. Hence , `DeltaH` is negative. Also, two moles of atoms have more randomness than one mole of a molecule. Since spontaneity is decreased , `DeltaS` is negative for the given reaction.

Discussion

309.	An ice cube of unknown mass at `0^(@)C` is added to 265g of `H_(2)O` at `25.00^(@)C` in a calorimeter. If the final temperature of the resulting `H_(2)O` is `21.70^(@)C`, what is the mass of the ice cube? A. `2.47g`B. `8.63g`C. `10.3g`D. `11.0g`
Answer» Correct Answer - B

Discussion

310.	For which exothermic reaction is `deltaE` more negative than `deltaH`?A. `Br_(2)(l)toBr_(2)(g)`B. `2C(s)+O_(2)(g) to 2CO(g)`C. `H_(2)(g)+F_(2)(g) to 2HF(g)`D. `2SO_(2)(g)+O_(2)(g) to 2SO_(2)(g)`
Answer» Correct Answer - B

Discussion

311.	Using the listed [`DeltaG_(f)^(@)` values] calculate `DeltaG^(@)` for the reaction : `3H_(2)S(g)[-33.6] +2HNO_(3)(l)[-80.6]rarr2NO(g)[+86.6]+4H_(2)O(l)[-237.1]+3S(s)[0.0]`A. `-513.2`B. `-1037.0`C. `+433.4`D. `+225.0`
Answer» Correct Answer - A `DeltaG^(@)=2xx86.6+4xx(-237.1)` `" "+3xx0-3(-33.6)` `" "-2(-80.6)=-513.2`

Discussion

312.	300 पर एक अभिक्रिया के लिए साम्य स्थिरांक 10 है\| `DeltaG^(ө)` का मान क्या होगा ? `R=8.314 JK^(-1) "mol"^(-1)`A. `-5.74kJ`B. `-574kJ`C. `+11.48kJ`D. `+5.74kJ`
Answer» Correct Answer - A `DeltaG= -2.303RT log K` `=-2.303xx8.314xx300 log 10` `=-5744.1 J rArr -5.74 kJ`

Discussion

313.	For the reaction, , `2A(g)+B(g) rarr 2D(g), DeltaU^(@) = - 10.5 kJ` and`DeltaS^(@) = - 44.10JK^(-1)` Calculate `DeltaG^(@)` for the reaction and predict whether the reaction may occur spontaneously.
Answer» For the given reaction,`Deltan_(g) =2- ( 3)= - 1` `:. DeltaH^(@) =DeltaU^(@) + Deltan_(g) RT =- 10.5 kJ + ( -1) ( 8.314 xx 10^(-3) kJ ) ( 298) = - 10.5-2.48= - 12.98 kJ` `DeltaG^(@) = DeltaH^(@)- T DeltaS=-12.98 kJ -298 ( -44.1xx 10^(-3) kJ)=-12.98 kJ+13.14 kJ =0.16 kJ ` As`DeltaG^(@) `comes out to be `+ve`,the reaction will not occur spontaneously.

Discussion

314.	For reaction, `2K_((g))+L_((g))rarr2M_((g)),DeltaU^(@)=-"10.5 KJ and "DeltaS^(@)=-"44.1 J K"^(-1)`. Calculate `DeltaG^(@)` for the reaction and predict whether the reaction will be spontaneous or non-spontaneous?A. `DeltaG=+"0.16 kJ, non-spontaneous"`B. `DeltaG=-"0.16 kJ, spontaneous"`C. `DeltaG=+"26.12 kJ, non-spontaneous"`D. `DeltaG=-"26.12 kJ, spontaneous"`
Answer» Correct Answer - A `2K+L rarr 2M` `Deltan_(g)=2-3=-1` `DeltaH=DeltaU+Deltan_(g)RT=-10.5xx10^(3)+(-1xx8.314xx298)` `=-10500+(-2477.572)=-12977.57J=-12.98kJ` `DeltaG^(@)=DeltaH^(@)-TDeltaS^(@)=-12.98-298(-44.1xx10^(-3))` `=-12.98+13.14=0.16kJ` Since `DeltaG^(@)` is `+ve` hence it is non-spontaneous.

Discussion

315.	For the reaction, `2A(g)+B(g) rarr 2D(g)` `DeltaU^(Θ)=-10.5 kJ` and `DeltaS^(Θ)=-44.1 JK^(-1)` Calculate `DeltaG^(Θ)` for the reaction, and predict whether the reaction may occur spontaneously.
Answer» Correct Answer - `0.164 kJ,` the reaction is not spontaneous. For the given reaction , `2A_((g))+B_((g))rarr2D_((g))` `Deltan_(g)=2-(3)` 1-mole Substituting the value of `Delta^(theta)` in the expression of `DeltaH:` `DeltaH^(theta)=DeltaU^(theta)+Deltan_(g)RT` `=(-10.5 kJ)-(-1)(8.314xx10^(-3)kJ K^(-1)"mol"^(-1))(298 K)` `=-10.5kJ-2.48 kJ` `DeltaH^(theta)=-12.98 kJ` Subtituting the value of `DeltaH^(theta) and DeltaS^(theta)` in the expression of `DeltaG^(theta):` `DeltaG^(theta)=DeltaH^(theta)-TDeltaS^(theta)` `=-12.98 kJ -(298 K)(-44.1 j K^(-1))` `=-12.98 kJ +13.14 kJ` `DeltaG^(theta)=+0.16 kJ` Since `DeltaG^(theta)` for the reaction is positive, the reaction will not occur spontaneously.

Discussion

316.	Give the mathematical expression of enthalpy.
Answer» Mathematically, H = U + pv where U is internal energy.

316.

Give the mathematical expression of enthalpy.

Answer»

Mathematically,

H = U + pv where U is internal energy.

Discussion

317.	When is enthalpy change (ΔH ) -(i) positive (ii) negative.
Answer» (i) ΔH is positive for endothermic reaction which absorbs heat from the surroundings. (ii) ΔH is negative for exothermic reactions which evolve heat to the surroundings.

317.

When is enthalpy change (ΔH ) -(i) positive (ii) negative.

Answer»

(i) ΔH is positive for endothermic reaction which absorbs heat from the surroundings.

(ii) ΔH is negative for exothermic reactions which evolve heat to the surroundings.

Discussion

318.	A gas is allowed to expand reversibly under adiabatic conditions. What is zero for such a process ?A. `Delta G = 0`B. `Delta T = 0`C. `Delta S = 0`D. None of these
Answer» Correct Answer - C

Discussion

319.	If `DeltaH` for a reaction has a positive value, how would you know the sign requirement of `DeltaS` for it so that the reaction is spontaneous?
Answer» Correct Answer - `DeltaG=DeltaH-TDeltaS` For spontaneous reaction `DeltaG=(-)ve" "therefore DeltaS` should be positive

Discussion

320.	An exothermic reaction `A rarr B` is spontaneous in the backward direction. What will be the sign of `DeltaS` for the forward reaction ?
Answer» Backward reaction will be endothermic . Thus, energy factor opposesthe backward reaction. As backward reaction is spontaneous , randomness factor must favour, i.e.,`DeltaS` will be`+ve` for the backward reaction orit will be `-ve` for forward reaction.

Discussion

321.	Which of the following enthalpy is always positive ?A. Enthalpy of solutionB. Enthalpy of formationC. Enthalpy of phase trasitionD. none of these
Answer» Correct Answer - d

Discussion

322.	Heat produced by burning 1 mol carbon with `O_(2)` to `CO_(2)` is 80 KJ and by maximum amount of heat produced on burning 30 g carbon with 48G `O_(2)`:A. 40KJB. 65KJC. 160KJD. 140KJ
Answer» Correct Answer - d

Discussion

323.	During an adiabatic reversibly expansion of an ideal gasA. Internal energy of the system decreases.B. Temperature of the system decreases.C. The value of `gamma` changesD. Pressure increases.
Answer» In adiabatic process, `q = 0`. Hence, in expansion process, temperature decreases and hence internal enegry also decreases.

Discussion

324.	Which reaction has the most positive entropy change understandard conditions?A. `H_(2)O(g) +CO(g) to H_(2)(g) +CO(g)`B. `CaCO_(3)(s) to CaO(s) to +CO_(2)(g)`C. `NH_(3)(g) to NH_(3)(aq)`D. `C_(8)H_(18)(g) to C_(8)H_(18)(s)`
Answer» Correct Answer - B

Discussion

325.	What are the sign of `DeltaH and DeltaS` for a reaction that is spontaneous only at low temperatures?A. `DeltaH` is positve, `DeltaS` is positiveB. `DeltaH` is positve, `DeltaS` is negativeC. `DeltaH` is negative, `DeltaS` is negativeD. `DeltaH` is negative, `DeltaS` is positive
Answer» Correct Answer - C

Discussion

326.	During isothermal expansion of an ideal gas, its:A. Internal energy increaseB. Enthalpy decreaseC. Internal energy and heat enthalpy remains constantD. Enthalpy reduces to zero
Answer» Correct Answer - C Thus heat given is used in doing work producing no change in internal energy.

Discussion

327.	4g `NH_(4)NO_(3)` were dissolved in 100 g water in bomb calorimeter with heat capacity of calorimether system 150`JK^(-1).`the temperature dropped by 1.5 K Enthalpy of solution of `NH_(4)NO_(3)`is :A. `450KJmol^(-1)`B. `-450KJmol^(-1)`C. `4.5KJmol^(-1)`D. `-4.5KJ mol^(-1)`
Answer» Correct Answer - c

Discussion

328.	A quantity of `1.534 g` of naphthanlene `(C_(10) H_(g))` is burned in constant-volume bomb calorimeter. Consequently, the temperature of the water rises form `20.00^(@)C` to `25.00^(@)C`. If the quanity of water surrounding the calorimeter is exactly `3000g` calculate the heat capcity of combustion of one mole of naphthalene (molar heat of combustion) Strategy : First calculate the heat changes for the water and the bomb calroimeter. using Finally, divide the value by the number of moles of naphthlene to calculate the molar heat of combusiton. Remember ot change `2.75 kJ^(@)C^(-1)` to `2.75 xx 1000 j^(@)C C^(-1)`
Answer» `q_(water) = m_(water) C_(water) Delta V` `= (3000 g) (4.184 J g^(-1) 1^(@)C^(-1)) (25^(@)C - 20^(@)C)` `= 6.28 xx 10^(4) J` `q_(bomb) = C_(bomb) Delta V` `= (2.75 xx 1000 J^(@)C^(-1)) (25^(@)C - 20^(@)C)` `= 1.38 xx 10^(4) J` From Eq., we write `q_(reaction) = - (6.28 xx 10^(4) J + 13.8 xx 10^(4) J)` ` = - 7.66 xx 10^(4) J`

Discussion

329.	Indicate in which case/cases the spontaneity of a change is favoured whenA. `DeltaH` `is` `+ve`B. `DeltaH` `is` `-ve`C. `DeltaS` `is` `+ve`D. `DeltaG` `is` `-ve`
Answer» In spontaneous process, `DeltaG =- ve, DeltaH =- ve`, and `DeltaS = +ve`

Discussion

330.	For the adiabatic expansion of an ideal asA. `PV^(gamma) =` constantB. `TV^(gamma-1)=` constantC. `TP^(1-gamma)` =constantD. None of the above
Answer» Mathmetical relation

Discussion

331.	When 0.36 g of glucose was burned in a bomb calorimeter ( Heat capacity `600 JK^(-1)`)the temperature rise by 10 K. Calculate the standard molar enthalpy of combustion (MJ/mole).
Answer» Correct Answer - 3 `C_(6)H_(12)O_(6)(S) + 6O^(2)(g) rarr 6CO^(2) (g) + 6H_(2)O(l)` No. of Mole of `C_(6)H_(12)O_(6) = (0.36)/(180) = 2 xx 10^(-3)`mole `C=(q)/(DeltaT) " " therefore" " q=C xx Delta T = 600 xx 10 J = 6KJ` Heat released per mole `=(6)/(2 xx 10^(-3)) = 3 xx 10^(3)KJ =3MJ` `Delta U =-3ML` `DeltaH = DeltaU + Deltan_(g)RT" " here " " Delta n_(g)=0` `Delta H = DeltaU =-3MJ "mole"^(-1)`

Discussion

332.	A boiled egg show `a//an`…… in entropy.A. IncreaseB. DecreaseC. No changeD. None of these
Answer» Correct Answer - A No doubt solidification show a decrease in entropy but in egg proteins structure are disorder in solid state due to denaturation.

Discussion

333.	Ethylene on combustion gives carbon dioxide and water. Its heat of combustion is `1410.0 kJ mol^(-1)`. If the heat of formation of `CO_(2)` and `H_(2)O` are `393.3 kJ` and `286.2 kJ`, respectively. Calculate the heat of formation of ethylene.
Answer» a. `CH_(2) = CH_(2)(g) +3O_(2)(g) rarr 2CO_(2)(g) +2H_(2)O DeltaH_(1) - 1410 K mol^(-1)` b. `C(s) +O_(2)(g) rarr CO_(2)(g)` `DeltaH_(2) = - 393.3 kJ mol^(-1)` c. `H_(2)(g) +(1)/(2)O_(2)(g) rarr H_(2)O(l)` `DeltaH_(2) =- 286.2 kJ mol^(-1)` To calculate `DeltaH` of the reaction: `2C(s) +2H_(2)(g) rarr CH_(2) = CH_(2)(g) DeltaH = ?` `:. DeltaH = 2DeltaH_(2) +2DeltaH_(2) - DeltaH_(1)` `= 2 xx -393.3 -2 xx 286.2 -(-1410)` `= 51.0 kJ mol^(-1)`

Discussion

334.	What is `DeltaG^(@)` for the reaction? `(1)/(2)N_(2)(g)+(3)/(2)H_(2)(g) to NH_(3)(g)` `K_(p)=4.42xx10^(4) at 25^(@)C.`A. `-26.5kJ. mol^(-1)`B. `-11.5kJ. mol^(-1)`C. `-2.2kJ. mol^(-1)`D. `-0.97kJ. mol^(-1)`
Answer» Correct Answer - A

Discussion

335.	Change in entropy is negative forA. Bromine`(l)to`Bromine`(g)`B. `C(s)+H_(2)O(g)toCO(g)+H_(g)`C. `N_(2)(g,10 atm)N_(2)(g,1 atm)`D. `Fe(1 mol e,400 K)toFe(1 mol e,300 K)`
Answer» Correct Answer - D The gaseous phase have more entropy and thus `DeltaS` is +ve in (a) and (b). Alos decrease in pressure increase disorder and thus `DeltaS` is `+ve` in (c). In (d)the disorder decrease in solid state due to decrease in temperature. Thus `DeltaS=-ve`

Discussion

336.	What is `DeltaG^(ɵ)` for the following reaction? `1/2 N_(2)(g)+3/2 H_(2)(g) hArr NH_(3)(g), K_(p)=4.42xx10^(4)` at `25^(@)C`A. `-26.5 kJ mol^(-1)`B. `-11.5 kJ mol^(-1)`C. `-2.2 kJ mol^(-1)`D. `-0.97 kJ mol^(-1)`
Answer» `DeltaG^(Theta) =- 2.303 RT logK_(p)` `=- 2.303 xx 8.314 xx 298 log (4.42 xx 10^(4))` `= - 26.5 kJ mol^(-1)`

Discussion

337.	In which of the following entropy increases?A. Rusting of ironB. Melting of iceC. Crystallisation of sugar from solutionD. Vaporisation of camphor
Answer» In conversion of solid ice to liquid and in reuting, the entropy increases.

Discussion

338.	Which of the following affect the heat of reaction?A. Physical states of reactants and productsB. Allotrpoic forms of elementsC. TemperatureD. Reaction carried out at constant pressure or constant volume
Answer» In all these process heat of reaction changes

Discussion

339.	The `DeltaG` in the process of melting of ice at `-15^@C` is :A. `DeltaG is -ve`B. `DeltaG is +ve`C. `DeltaG=0`D. All of these
Answer» Correct Answer - B The melting of ice at `-15 ^(@)C` is not an spontaneous process.

Discussion

340.	The `DeltaG` in the process of melting of ice at `-15^@C` is :A. `Delta G` is -VeB. `Delta G` is +VeC. `Delta = 0`D. All of these
Answer» Correct Answer - B Ice `hArr` water is not possible at -15 degree centigrade. So, `Delta G gt 0`

Discussion

341.	What is the entropy change for the conversion of one gram of ice to water at 167 K and one atmospheric pressure ? `[Delta H_("fussion") = 6.025 kJ mol^(-1)]`
Answer» Correct Answer - 2 `Delta _("fusion") S = (Delta_("fusion")H)/(T_(f)) rArr (6.025 xx 10^(3))/(167) xx (1)/(18)`

Discussion

342.	The enthalpy of transition of crustalline boron to amorphous boron at `1500^(@)C` is 0.4 kcal "mole"^(-1)`. Assuming at.wt of boron 10, the change in enthaplpy of transition 50 g boron from crystalline to amorphous form is
Answer» Correct Answer - 5 `1 mol - 0.4 K.cal rArr 10 g - 0.4 K cal, 50 - ?`

Discussion

343.	For a certain `A(g)to B(g)` at equillibrium . The parital pressure of B is found to be one fourth of the partial pressure of A. The value of `DeltaG^(@)` of the reaction ` A to B` is:A. RT ln 4B. `-RT ln 4`C. RT lig 4D. `-RT log 4`
Answer» Correct Answer - A `Delta G^(@) = -RT ln K`

Discussion

344.	For a certain `A(g)to B(g)` at equillibrium . The parital pressure of B is found to be one fourth of the partial pressure of A. The value of `DeltaG^(@)` of the reaction ` A to B` is:A. `RT In 4`B. `-RT In 4`C. `RT log 4`D. `-RT log 4`
Answer» Correct Answer - A

Discussion

345.	A reaction has `DeltaH=-33kJ and DeltaS=-58J//K`. This reaction would be:A. spontaneous at all temperature.B. non-spontaneous at all temperatures.C. spontaneous above a certain temperature.D. spontaneous below a certain temperature.
Answer» Correct Answer - D

Discussion

346.	A solution of `500mL` of `2M KOH` is added to `500mL` of `2M HCl` and the mixture is well shaken. The rise in temperature `T_(1)` is noted. The experiment is then repeated using `250mL` of each solution and rise in temperature `T_(2)` is againg noted. Assume all heat is taken up by the solution `:`A. `T_(1)=T_(2)`B. `T_(1)` is 2 times as large as `T_(2)`C. `T_(2)` is twice of `T_(1)`D. `T_(1)` is 4 times as large as `T_(2)`
Answer» Correct Answer - A

Discussion

347.	A solution is 500 ml of 2M KOH is added to 500 ml of 2 M HCl and the mixture is well shaken. The rise in temperature `T_(1)` is noted. The experiment is then repeated using `250 ml` of each solution and rise in temperature `T_(2)` is again noted. Assume all heat is taken by the solutionA. `T_(1)=T_(2)`B. `T_(1)` is 2 times as large as `T_(2)`C. `T_(2)` is twice of `T_(1)`D. `T_(1)` is 4 times as large as `T_(2)`
Answer» Correct Answer - A

Discussion

348.	The average O-H bond energy in `H_(2)O` with the help of following data. (1) `H_(2)O(l)rarrH_(2)O(g), Delta H= +40.6 kJ mol^(-1)` (2) `2H(g)rarrH_(2)(g), DeltaH= -435.kJ mol^(-1)` (3) `O_(2)(g)rarr2O(g), Delta H= +489.6 kJ mol^(-1)` (4) `2H_(2)(g)+O_(2)(g)rarr2H_(2)O(l), Delta H= -571.6 kJ mol^(-1)`A. `584.9 kJ mol^(-1)`B. `279.8 kJ mol^(-1)`C. `462.5 kJ mol^(-1)`D. `925 kJ mol^(-1)`
Answer» Correct Answer - C Assuming density of solution is `1g//c c` and specific heat is `4.2 J//gc` `=msDelta T=100xx4.2xx3` millimoles of acid neutralized `=5` `DeltaH= - 100xx4.2xx3xx(1000)/(5)= -2.52xx10^(2)KJ//"mole"`.

Discussion

349.	Calculate the work done when 1 moleof an ideal gas is compressed reversibly from 1.0 bar to 4.00 bar at constant temperature of 300KA. `3.46 kJ`B. `-8.20 kJ`C. `18.02kJ`D. `-14.01kJ`
Answer» Correct Answer - A `w= - 2.303 nRT log. (P_(1))/(P_(2))= - 2.303 xx 1 xx 8.314 xx 300 log. (1)/(4) = 3458J = 3.458 kJ`

Discussion

350.	Rank the following in the order of increasing entropy `:` (a) 1 mole of `H_(2)O(l)` at `25^(@)C` and 1 atm. Pressure. (b) 2 moleof `H_(2)O(s)` at `0^(@)C` and 1 atm. Pressure. (c ) 1 moleof `H_(2) O(v)` at `100^(@)C` and 1 atm. Pressure. (d) 1 mole of `H_(2)O(l)` at `0^(@)C` and 1 atm. pressure.
Answer» (b) `lt (d) lt (a) lt (c )`. This is because solid is less random than liquid which is tun is less random than gas .For the same state, at the same pressure, higher the temperature , greater is the randomness.

Discussion

Explore topic-wise InterviewSolutions in .

The difference in `DeltaH` and `DeltaE` for the combustion of ethane at `27^(@)C` would beA. `Delta H gt Delta E`B. `Delta H lt Delta E`C. `Delta H=Delta E`D. No relation

For is reaction involving only liquid reactants & liquid products the relationship between `DeltaH` and `DeltaE` isA. `Delta H gt Delta E`B. `Delta H lt Delta E`C. `Delta H=Delta E`D. `Delta E ge Delta H`

`DeltaH gt DeltaE` for the reactionA. `CH_(4)(g)+2O_(2)(g) rarr CO_(2)(g) +2H_(2)O(g)`B. `N_(2)(g)+3H_(2)(g) rarr 2NH_(3) (g)`C. `C_(2)H_(4)(g) +3O_(2)(g) rarr 2CO_(2)(g) +2H_(2)O(g)`D. `CaCO_(3)(s) rarr CaO(s) +CO_(2)(g)`

For which of the following reactions `DeltaH=DeltaE+2RT`A. `N_(2)(g)+3H_(2)(g) rarr 2NH_(3)(g)`B. `N_(2)(g)+O_(2)(g) rarr 2NO(g)`C. `NH_(4)HS(s) rarr NH_(3)(g)+H_(2)S(g)`D. `PCl_(5)(g) rarr PCl_(3)(g)+Cl_(2)(g)`

For the reaction `A rarr B,DeltaH = + 24 kJ //`mole For the reaction `B rarrC , DeltaH= -18 kJ `// mole . The decreasing order of enthalpy of A,B,C follows the order `:`A. A,B,CB. B,C,AC. C,B,AD. C,A,B

For the reaction `2Cl(g) rarr Cl_(2)(g)`, what are the signs of `DeltaH` and `DeltaS`?

An ice cube of unknown mass at `0^(@)C` is added to 265g of `H_(2)O` at `25.00^(@)C` in a calorimeter. If the final temperature of the resulting `H_(2)O` is `21.70^(@)C`, what is the mass of the ice cube? A. `2.47g`B. `8.63g`C. `10.3g`D. `11.0g`

For which exothermic reaction is `deltaE` more negative than `deltaH`?A. `Br_(2)(l)toBr_(2)(g)`B. `2C(s)+O_(2)(g) to 2CO(g)`C. `H_(2)(g)+F_(2)(g) to 2HF(g)`D. `2SO_(2)(g)+O_(2)(g) to 2SO_(2)(g)`

Using the listed [`DeltaG_(f)^(@)` values] calculate `DeltaG^(@)` for the reaction : `3H_(2)S(g)[-33.6] +2HNO_(3)(l)[-80.6]rarr2NO(g)[+86.6]+4H_(2)O(l)[-237.1]+3S(s)[0.0]`A. `-513.2`B. `-1037.0`C. `+433.4`D. `+225.0`

300 पर एक अभिक्रिया के लिए साम्य स्थिरांक 10 है| `DeltaG^(ө)` का मान क्या होगा ? `R=8.314 JK^(-1) "mol"^(-1)`A. `-5.74kJ`B. `-574kJ`C. `+11.48kJ`D. `+5.74kJ`

For the reaction, , `2A(g)+B(g) rarr 2D(g), DeltaU^(@) = - 10.5 kJ` and`DeltaS^(@) = - 44.10JK^(-1)` Calculate `DeltaG^(@)` for the reaction and predict whether the reaction may occur spontaneously.

For the reaction, `2A(g)+B(g) rarr 2D(g)` `DeltaU^(Θ)=-10.5 kJ` and `DeltaS^(Θ)=-44.1 JK^(-1)` Calculate `DeltaG^(Θ)` for the reaction, and predict whether the reaction may occur spontaneously.

Give the mathematical expression of enthalpy.

When is enthalpy change (ΔH ) -(i) positive (ii) negative.

A gas is allowed to expand reversibly under adiabatic conditions. What is zero for such a process ?A. `Delta G = 0`B. `Delta T = 0`C. `Delta S = 0`D. None of these

If `DeltaH` for a reaction has a positive value, how would you know the sign requirement of `DeltaS` for it so that the reaction is spontaneous?

An exothermic reaction `A rarr B` is spontaneous in the backward direction. What will be the sign of `DeltaS` for the forward reaction ?

Which of the following enthalpy is always positive ?A. Enthalpy of solutionB. Enthalpy of formationC. Enthalpy of phase trasitionD. none of these

Heat produced by burning 1 mol carbon with `O_(2)` to `CO_(2)` is 80 KJ and by maximum amount of heat produced on burning 30 g carbon with 48G `O_(2)`:A. 40KJB. 65KJC. 160KJD. 140KJ

During an adiabatic reversibly expansion of an ideal gasA. Internal energy of the system decreases.B. Temperature of the system decreases.C. The value of `gamma` changesD. Pressure increases.

Which reaction has the most positive entropy change understandard conditions?A. `H_(2)O(g) +CO(g) to H_(2)(g) +CO(g)`B. `CaCO_(3)(s) to CaO(s) to +CO_(2)(g)`C. `NH_(3)(g) to NH_(3)(aq)`D. `C_(8)H_(18)(g) to C_(8)H_(18)(s)`

What are the sign of `DeltaH and DeltaS` for a reaction that is spontaneous only at low temperatures?A. `DeltaH` is positve, `DeltaS` is positiveB. `DeltaH` is positve, `DeltaS` is negativeC. `DeltaH` is negative, `DeltaS` is negativeD. `DeltaH` is negative, `DeltaS` is positive

During isothermal expansion of an ideal gas, its:A. Internal energy increaseB. Enthalpy decreaseC. Internal energy and heat enthalpy remains constantD. Enthalpy reduces to zero

4g `NH_(4)NO_(3)` were dissolved in 100 g water in bomb calorimeter with heat capacity of calorimether system 150`JK^(-1).`the temperature dropped by 1.5 K Enthalpy of solution of `NH_(4)NO_(3)`is :A. `450KJmol^(-1)`B. `-450KJmol^(-1)`C. `4.5KJmol^(-1)`D. `-4.5KJ mol^(-1)`

Indicate in which case/cases the spontaneity of a change is favoured whenA. `DeltaH` `is` `+ve`B. `DeltaH` `is` `-ve`C. `DeltaS` `is` `+ve`D. `DeltaG` `is` `-ve`

For the adiabatic expansion of an ideal asA. `PV^(gamma) =` constantB. `TV^(gamma-1)=` constantC. `TP^(1-gamma)` =constantD. None of the above

When 0.36 g of glucose was burned in a bomb calorimeter ( Heat capacity `600 JK^(-1)`)the temperature rise by 10 K. Calculate the standard molar enthalpy of combustion (MJ/mole).

A boiled egg show `a//an`…… in entropy.A. IncreaseB. DecreaseC. No changeD. None of these

Ethylene on combustion gives carbon dioxide and water. Its heat of combustion is `1410.0 kJ mol^(-1)`. If the heat of formation of `CO_(2)` and `H_(2)O` are `393.3 kJ` and `286.2 kJ`, respectively. Calculate the heat of formation of ethylene.

What is `DeltaG^(@)` for the reaction? `(1)/(2)N_(2)(g)+(3)/(2)H_(2)(g) to NH_(3)(g)` `K_(p)=4.42xx10^(4) at 25^(@)C.`A. `-26.5kJ. mol^(-1)`B. `-11.5kJ. mol^(-1)`C. `-2.2kJ. mol^(-1)`D. `-0.97kJ. mol^(-1)`

Change in entropy is negative forA. Bromine`(l)to`Bromine`(g)`B. `C(s)+H_(2)O(g)toCO(g)+H_(g)`C. `N_(2)(g,10 atm)N_(2)(g,1 atm)`D. `Fe(1 mol e,400 K)toFe(1 mol e,300 K)`

What is `DeltaG^(ɵ)` for the following reaction? `1/2 N_(2)(g)+3/2 H_(2)(g) hArr NH_(3)(g), K_(p)=4.42xx10^(4)` at `25^(@)C`A. `-26.5 kJ mol^(-1)`B. `-11.5 kJ mol^(-1)`C. `-2.2 kJ mol^(-1)`D. `-0.97 kJ mol^(-1)`

In which of the following entropy increases?A. Rusting of ironB. Melting of iceC. Crystallisation of sugar from solutionD. Vaporisation of camphor

Which of the following affect the heat of reaction?A. Physical states of reactants and productsB. Allotrpoic forms of elementsC. TemperatureD. Reaction carried out at constant pressure or constant volume

The `DeltaG` in the process of melting of ice at `-15^@C` is :A. `DeltaG is -ve`B. `DeltaG is +ve`C. `DeltaG=0`D. All of these

The `DeltaG` in the process of melting of ice at `-15^@C` is :A. `Delta G` is -VeB. `Delta G` is +VeC. `Delta = 0`D. All of these

What is the entropy change for the conversion of one gram of ice to water at 167 K and one atmospheric pressure ? `[Delta H_("fussion") = 6.025 kJ mol^(-1)]`

The enthalpy of transition of crustalline boron to amorphous boron at `1500^(@)C` is 0.4 kcal "mole"^(-1)`. Assuming at.wt of boron 10, the change in enthaplpy of transition 50 g boron from crystalline to amorphous form is

For a certain `A(g)to B(g)` at equillibrium . The parital pressure of B is found to be one fourth of the partial pressure of A. The value of `DeltaG^(@)` of the reaction ` A to B` is:A. RT ln 4B. `-RT ln 4`C. RT lig 4D. `-RT log 4`

For a certain `A(g)to B(g)` at equillibrium . The parital pressure of B is found to be one fourth of the partial pressure of A. The value of `DeltaG^(@)` of the reaction ` A to B` is:A. `RT In 4`B. `-RT In 4`C. `RT log 4`D. `-RT log 4`

A reaction has `DeltaH=-33kJ and DeltaS=-58J//K`. This reaction would be:A. spontaneous at all temperature.B. non-spontaneous at all temperatures.C. spontaneous above a certain temperature.D. spontaneous below a certain temperature.

Calculate the work done when 1 moleof an ideal gas is compressed reversibly from 1.0 bar to 4.00 bar at constant temperature of 300KA. `3.46 kJ`B. `-8.20 kJ`C. `18.02kJ`D. `-14.01kJ`

Rank the following in the order of increasing entropy `:` (a) 1 mole of `H_(2)O(l)` at `25^(@)C` and 1 atm. Pressure. (b) 2 moleof `H_(2)O(s)` at `0^(@)C` and 1 atm. Pressure. (c ) 1 moleof `H_(2) O(v)` at `100^(@)C` and 1 atm. Pressure. (d) 1 mole of `H_(2)O(l)` at `0^(@)C` and 1 atm. pressure.