Energetics Questions and Answers

7 Arrange the following alcohols in order of increasing reactivity towards sodium metal 1 CH3 3COH ii CH3 2CH OH iii CH3CH OH 1 iii ii i 2 ii i iii 3 i ii iii 4 iii i ii

4 Gases will occupy a definite space The increasing order of crystal field splitting strength of the given ligands 1 NH C CN F C0 H 0 2 F C NH CN H 0 C0 3 CF F H 0 NH CN CO 4 CO CN NH H O F CT

In a certain chemical reaction AH 150 kJ and AS 10 Question Type Single Correct Type 1 2 3 K at 300K The value of AG is 4 138 kJ 138 kJ 147 kJ 147 kJ

For the reversible isothermal expansion of one mole of an ideal gas at 300 K from a volume of 10 dm to 20 dm AH is 1 1 73 kJ 3 3 46 kJ 2 1 73 kJ 4 Zero Old CO g at 977 C

During the adsorption of Krypton on activated charcoal at low temperature Question Type Single Correct Type 1 AH 0 and ASgas 0 2 AH 0 and ASgas 0 3 AH 0 and ASgas 0 4 AH 0 and ASgar 0

7 For a sample of perfect gas when its pressure is changed isothermally from p to p the entropy change is given by a AS nR In Pf Pi c AS nRT In Pf Pi Pi In A Pf b AS nR In d AS RT In Pi Pf

Which of the graphs shown below does not represent the relationship between incident light and the electron ejected from metal surface A B K E of es 0 K E of es 0 Intensity of Light

1 The enthalpy of fusion of water is 1 435 kcal mol The molar entropy change for the melting of ice at 0 C is a 10 52 cal mol K c 5 260 cal mol K b 21 04 cal mol K d 0 526 cal mol K

Enthalpy of sublimation of iodine is 1 24 cal g at 200 C If specific heat of 12 s and 12 vap are 0 055 and 1 0 031 cal g K respectively then enthalpy of sublimation of iodine at 1 250 C in cal g is A B 22 8 11 4 1 C 2 85 D 5 7

If a reaction has a Kea 1 and all reaction components are at 1 M then the reaction will proceed in the direction and AG for the forward reaction will be reverse negative O reverse positive O forward negative O forward positive O Cannot be determined

Predict which of the following reaction s has a positiv entropy change 1 Ag aq Cl aq AgCl s ii NH4Cl g NH3 g HCl g iii 2NH3 g N g 3H g 1 i ii 2 iii 3 ii iii

1 100 C 2 0 C 3 373 K 4 273 C 24 The molar entropy of the vapourization of acetic acid is 14 4 cal K mol at its boiling point 118 C The latent heat of vapourization of acetic acid is 1 49 cal g neet prep This solute may be 1 CaSO4 2 CuSO4 temperature and is given as S Ae AH RT Here AH is enthalpy of the solution For the gir solute variation of log S with temperature can be sho by the figure given below log S 1 T Mini Test 17 Spontaneity Entropy Contact Number 9667591930 85275211

The reaction of carbon monoxide and iodine pentoxide as represented by the equation 2 is endothermic in nature Explain the effect by which we can increase the product formation 5 CO g I Os g 1 g 5 CO g

18 Antistokes lines in Raman spectra is observed when d Av V V is ve c Vi V s a V V b Vi VS 19 Intensity of stokes lines is

b E ele Evib Erot c Ecle Evib Erot vibration rotation spectra is given by b Av 1 AJ 1 d AJ 1 a E ele X Evib XE rot 17 R branch in a Av 1 AJ 1 c Av 1 AJ 1 1 uhon a ele vib E

Question No 9 If enthalpy of combustion of C s H g and C H6 g are x y and z kJ mol respectively then enthalpy of formation of ethane will be O x y z Oz x y Oz 2x 3y O 2x 3y Z

The heat of at 27 C combustion of benzene measured by bomb calorimeter for the reaction C6H6 e 7 02 g 6CO2 g is 780 kcal 1 mol The heat evolved on on burning 39 g of benzene at 27 C in an open vessel will be A 230kcal B 780kcal 390 45kcal 190 51ool

The enthalpy of neutralization of HCI and NaOH is 57 kJ mol The heat evolved at constant pressure in kJ when 0 5 mole of H SO4 react with 0 75 mole of NaOH is equal to B 57x0 5 D 57x0 25 3 A 57x 4 C 57 SPACE FOR ROUGH WORK

If 1 mol of HA weak monobasic acid is neutralised by 1 mol of NaOH and total heat released is used to raise temperature of 7 mol of ice from 10 C to 10 C If heat of neutralisation of 1 mole of strong acid with 1 mole of strong base is 57 057 kJ heat of ionisation of HA in kJ mol is Afusion of ice 6 03 kJ mol 1 Cp H 0 1 75 3 J mol K 1 Cp H 0 s 36 8 J mol K 1

For which of the following acid base pair enthalpy of neutralisation is 13 7 kcal CH3COOH NaOH CH3COOH NH4OH NH4OH HCI NaOH HCI

According to third law of thermodynamics which property of any pure crystalline substances approaches zero as the temperature approaches absolute zero U H

The enthalpy changes at 298 K in successive breaking of O H bonds of H O Hare H OH g H O OH H O g The bond enthalpy of the O H bond is 11492 1 498 kJ mol 2 463 kJ mol 1 101 AH 498 kJ mol AH 428 kJ mol 3 428 kJ mol 4 70 kJ mot

Calculate the average A B bond energy in AB4 g AH for AB4 g 74 9 kJ mol AH for A g 155 3 kJ mo AH for B g 188 8 kJ mol AH for A2 g 0 kJ mol AH for B g 0 kJ mol Enter a number in kJ mol to 1 decimal place

If enthalpy of combustion of C s H g and C H6 g are x y and z kJ mol respectively then enthalpy of formation of ethane will be Ox y z Oz x y Oz 2x 3y 31 M

Que 20 An ideal gas is expanded by given thermodynamic process with same initial state to same final volume Which of the following is correct order of magnitude of work for given process 1 PV K 11 PV 2 K V II IV III I I II IV III III PV K3 IV PV K4

2 Calculate the work of system with isothermal compression where I mole of gas undergoes a pressure change from 1 bar to 58 bar at 130 C If gas follow equation of state PV Z 1 RT B 207 5 cm mol and C 18200 cm mol BP C B RT RT pa

Enthalpy of combustion of the reaction CH4 g O g CO g H O g is 890 kJ mol Calculate the how much heat is released when 25 0 g of methane is combusted A 1390 6 kJ B 1390 6 kJ C 890 kJ D 890 kJ

At the end of the reaction 0 75 L of gas was collected over water at 25 C and the total pressure measured was 766 mm Hg How many moles of H O2 were consumed by the reaction Given vapor pressure of water at 25 C 24 mm Hg R 0 0821 atm L mole 1 atm 760 mm Hg OA O B Oc OD 766 760 0 75 0 0821 2 25 273 15 766 24 760 0 75 2 0 0821 25 273 15 766 24 760 0 75 2 34 0158 0 0821 25 273 15 34 0158 0 75 25 273 15 HO 34 0158 g mole

Bond enthalpies of H H Cl Cl and H Cl bonds are 434 kJ mol 242 kJ mol and 431 kJ mol respectively Enthalpy of formation of HCl is a 245 kJ mol b 93 kJmol c 245 kJ mol 1 d 93 kJ mol

31 What is H in mol L of a solution that is 0 20 M 101 CH3COONa and 0 10 M in CH3COOH Ka for CH3COOH 1 8x10 5 AIPMT Prelims 2010 1 3 5 x 10 4 2 1 1 x 10 5 3 1 8 10 5IAT 4 9 0 x 10 6

3 Consider the cell reaction A s 2B aq A aq 2B s E cell of the reaction 2A s 4B aq 2A aq 4B s is given E A 2 A XV and E B B yv 1 y x V 2 2 y x v 3 2 x y v 4 y x v

IV Gibbs free Energy of Galvanic cell 1 Question 1 The value of AG in Joule for electrode reaction A e A will be given E A 3 A X V and E A 2 A y V F Faraday s constant 1 3x 2y F 2 3x 2y F 3 3x 2y F 4 3x 2y F

Identify the chemical reaction s in which the amount of heat evolved is so large that the metal is produced in the molten state a Reaction of solid iron oxide and solid aluminium b Reaction of zinc oxide and carbon c Reaction of manganese oxide and aluminium d Reaction of magnesium chloride solution and aluminium metal

137 At a constant temperature AS will be maximum for which of the following processes A Vaporisation of a pure solvent B Vaporisation of solvent from a solution containing nonvolatile and nonelectrolytic solute in it C Vaporisation of solvent from a solution 14 containing nonvolatile but electrolytic solute in it D Entropy change will be same in all the above cases

For the reaction 2NO g N O g AH 57 2 kJ mol 1 The value of K can be increased by C Options Adding NO Adding N O4 Increasing temperature Decreasing temperature Solution

2 1 0 H gas is mixed with air at 25 C under a pressure of 1 atmosphere and exploded in a closed vessel 1 The heat of the reaction H2 g O2 g H O v at constant volume AU298 K 240 60 kJ mol and Cy values for H O vapour and N in the temperature range 298 K and 3200 K are 39 06 JK mol and 26 40 JK mol respectively The explosion temperature under adiabatic conditions is Given N 2 a 2900 K c 2917 K b 2900 C d 3000 C

when 5 temperature of solution increases by t C Which of the following can be predicted from this observation A If 5 mL of 0 1M HCl is mixed with 5 mL 0 1 M NH3 solution the temperature rise will be less than t C B If 5 mL of 0 1 M CH3COOH is mixed with 5 mL 0 1 M NaOH the temperature rise will be less than t C C If 10 mL of 1 0 M HCI mixed with 10 mL of 0 1 M NaOH the temperature rise will be 2t C D If 10 mL of 0 1 M HCl is mixed with 10 mL of 0 1 M NaCl the temperature rise 11 L e

A fixed mass m of a gas is subjected to transformation of states from K to L to M to N and back to K as shown in the figure V K N L M P The succeeding operation that enable this transformation of state are

8 10 moles of a liquid L are 50 converted into its vapour at its boiling point 273 C and at a pressure of 1 atm If the value of latent heat of vapourisation of liquid L is 273 L atm mole then which of the following statements is are correct Assume volume of liquid to be negligible and vapour of the liquid to behave ideally A Work done by the system in the above process is 224 L atm B The enthalpy change AH for the above process is 1365 L atm with respect to magnitude only The entropy of the system increases by 2 5 L atm in the above process D The value of AU for the above process is 1589 L atm

3 01 mol of an ideal gas in a 73 6 L container at 25C calculate each of the following quantities indicated in problem 8 11 9 The heat absorbed qrev for revisible isothermal expansion to a at constant initial temperature

58 180 If heat of combustion of methane is 890 kJ mol then amount of heat released when 13 2 g of CO is produced on combustion of methane is 267 kJ 315 kJ 420 kJ Mark for Review 175 kJ

If 1 5 mols of gas is allowed to expand to twice its original volume while in contact with a thermal bath what is the change in entropy of the gas Provide your answer in units of the gas constant R do not include R in your answer

neet prep High Yieldin 107 The work done in ergs for the reversible expansion one mole of an ideal gas from a volume of 10 liters to 2 liters at 25 C is 1 2 303 x298 0 082 log 2 2 298 x 107 x 8 31 x2 303 log 2 3 2 303 x298 x 0 082 log 0 5 4 8 31 x 107 x 298 2 303 log 0 5

27 Assertion The number of tetrahedral voids is double the number of octahedral voids Reason The size of the tetrahedral voids is half of that of the octahedral void a If both assertion and reason are true and reason is the correct explanation of assertion b If both assertion and reason are true but reason is not the correct explanation of assertion If assertion is true but reason is false c

Which of the following statements about the advantage of roasting of sulphide ore before reduction is not true Question Type Single Correct Type 1 2 3 Roasting of the sulphide to the oxide is thermodynamically feasible Carbon and hydrogen are suitable reducing agents for all metal oxide The AfG of the sulphide is greater than oxide The AfG is negative for roasting of

An oxygen 0 molecule is adsorbed on a patch of surface see sketch at right This patch is known to contain 900 adsorptic sites The 0 molecule has enough energy to move from site to site so it could be on any one of them Suppose part of the surface becomes inaccessible so that only 784 adsorption sites are now available for the molecule Calculate the change in entropy Round your answer to 3 significant digits and be sure it has the correct unit symbol 0 2

Estimate the boiling point of an organic compound CnH2n 2 in unit of degree Celsius C given the following thermodynamic parameters Temperature conversion K C 273 15 CnH2n 2 liq CnH2n 2 gas AfH kJ mol S J K mol Please keep your answer with one decimal place 281 8 162 1 234 3 280 6

A calorimeter contains 130 g water The calorimeter and the water inside are both at 26 C A piece of metal weighing 35 g was heated to 90 C and then put into the water inside the calorimeter The equilibrium temperature was determined to be 35 C Assuming no heat is lost to the environment calculate the specific heat of the metal Calorimeter constant 120 1 Specific heat of water 4 184 JC OA 3 85 JC 1 08 254 J C OC 2 67 J C Q0 2 185 C 8 OE 3 10 J C g

1 At 300K the standard enthalpies of formation of CH COOH CO2 g and H O are 408 393 and 286 kJ mol respectively Calculate the heat of combustion of benzoic acid at contant volume 1 3201 kJ 2 3199 75 kJ 3 3201 kJ 4 3199 75 kJ

The following data were obtained in a bomb calorimeter experiment Weight of coal burnt 0 996g Weight of water in calorimeter 2490g Weight of bomb calorimeter etc 3900g Rise in temperature of water 2 592 C Find the higher calorific value of the fuel If the fuel sample contains 6 hydrogen calculate its lower calorific value latent heat of steam 587 cal g