Energetics Questions and Answers

31 The standard entropies of N 9 H g and NH g are 191 5 130 5 192 6 JK 1 mol 1 The value of AS of formation of ammonia is 1 98 9 JK 1 mol 1 3 129 4 JK 1 mol 1 2 Zero 4 29 4 JK 1 mol 1

For the reaction 2NO g O g 2NO g Calculate G at 700 K if change in enthalpy and entropy are 113kJ mol and 145J Kmol respectively Predict the spontaneity of the reaction The enthalpy change for the transition of water to steam Hvap 40 8KJ mol at 373K Calculate the entropy change for the process hono C CH Calculat 20 360 24 O

In this topic the energy kept on increasi ng then why all of a sudden did it go to 347 kJ Mean Bond Enthalpy In methane all the four C H bonds are identical in bond length and energy However the energies required to break the individual C H bonds in each successive step differ CH4 g CH3 g Hg Ac HH 427 kJ mol CH3 g CH2 g Hg AC HH 439 kJ mol 1 CH2 g CH g CH g Hg AC HH 452 kJ mol CH g C g H g Ac HH 347 kJ mol Over all reaction CH4 s C g 4H g

3 An argon atom with average translation energy 3kT 2 k is Boltzmann constant is confined in a cubic box of volume V 0 6 m at 298K a What is the energy difference AE between levels n and n 1 b Calculate the ratio of AE and KT and comment if particle is in classical or quantum limit Marks 6 00

A manufacturer reports a FAAS sensitivity for nickel of 0 059 mg L using the principal atomic absorption line and a stoichiometric air acetylene flame Assuming linearity and the same operating conditions this implies that the blank corrected absorbance for a solution containing 1 07 mg Ni L should be approximately a 0 020 absorbance units b 0 040 absorbance units c 0 060 absorbance units d 0 080 absorbance units

A cylinder of height 500 mm and diameter 50 mm is held vertically height wise in a room where the temperature of air is 30 C If the cylinder is maintained at a constant temperature of 90 C calculate rate of heat transfer from the cylinder to surrounding air

Calculate the energy required to heat 1 70 kg of ammonia from 48 1 C to 62 1 C Assume the specific heat capacity of ammonia under these 1 Conditions is 4 70 J g K 1 Round your answer to 3 significant digits 0 0 H

The relation between faradic current and time in AC polarography is O if is directly proportional with time O if is inversely proportional to time if is proportional to the square root of time O none of above

of enthalpy of combusti NCERT Pg 11 1 C H6 g O g 2CO g 3H O 1 2 C s O g CO g diamond 3 C s O g CO g graphite 2

3 Assuming that the dry matter of the wood biomass consists of 42 of cellulose calculate the efficiency of the SSF Simultaneous Saccharification Fermentation Compare with the efficiency of the SSF reaction performed on starch Explain C6H12O6 2 C2H5OH 2 CO2

Calculate AG and w for an isothermal expansion of 1 00 mol of an ideal gas wherein the external pressure changes as a function of internal pressure Pex 2P 100 Vatm from 2 478 L to 24 78 Lat 298 K

Consider the reaction 6CO g 6H O 1 C6H12O6 60 g for which AH 2 801x10 kJ and AS 259 0 J K at 298 15 K 1 Calculate the entropy change of the UNIVERSE when 2 260 moles of CO g react under standard conditions at 298 15 K ASuniverse J K 2 Is this reaction reactant or product favored under standard conditions 3 If the reaction is product favored is it enthalpy favored entropy favored or favored by both enthalpy and entropy If the reaction is reactant favored choose reactant

List 1 Condition for the system parameter when Non PV work is zero P dH 0 Tds dq R dU 0 List 11 Comment on the nature of spontaneity o the process 1 Spontaneous 2 Non Spontaneous 3 Equilibrium

What is the a molar enthalpy of the ammonium chloride water solution cal mol and b partial molar enthalpy of each component cal g given that mass of NH4Cl 0 103g mass of H2O 100g Specific enthalpy of solution 54 8533 cal g

8 Calculate the total heat in kJ required to convert 10 0 grams of liquid ethanol MM 46 07 g mol at its boiling point to gaseous ethanol at 158 C Note that not all of the data below is necessary for this problem AH 40 5 kJ mol AH 5 10 kJ mol 1 14 kl 6 28 kJ 9 93 kJ MP 115 C BP 78 C Cand 1 88 J g C Chand 2 45 J g C C 1 43 J g C

An ideal gas undergoes a mechanically reversible process constant pressure constant temperature and adiabatic process The gas entering a T1 650K and P1 10bar decreases its temperature at constant pressure where V2 2 91x10 3 m3 Then it went to isothermal process to decrease its pressure Finally the gas returns to its initial state Take Cp 7 2 and Cv 5 2 Calculate the following a T2 P3 V1 and V3 b Q W AU and AH

HERE IN THE QUESTION WHY CANT WE DI RECTLY USE FORMULA WHICH HAS DELTA PV AND WE KNOW DELTA V IS O SO TERM WOULD BE 0 BUT INSTEAD WHY WE USE DELTA N GAS RT FORMULA I AM VERY C ONFUSED WHEN TO USED FORMULA WHIC H HAS DELTA PV AND WHEN TO USE DELT AN GAS RT Enthalpy of combustion For the complete combustion of ethanol C H OH 30 g 200 g 34 0 the amount of heat released as measured in a bomb calorimeter is 1 364 47 kJ mot at 300 K Assuming ideality what will be the enthalpy of combustion 4 H for the reaction 25 0 a 1 366 97 kJ mot b 1 361 95 kJ moft c 1 460 50 kJ mo d 1 350 50 kJ mo

A group of students conducted an experiment using a coffee cup calorimeter Initially the calorimeter contained only deionized water and the temperature of the water was 21 24 C After adding a soluble ionic compound and stirring the temperature reached 23 56 C The temperature of the mixture rose because the water absorbed thermal energy from the ionic compound the solution absorbed heat from the surroundings the dissolution process was endothermic the dissolution process was exothermic

An analytical chemist is titrating 242 1 mL of a 0 5100M solution of aniline C6H5NH with a 0 3200M solution of HIO3 The p K of anilin is 9 37 Calculate the pH of the base solution after the chemist has added 442 2 mL of the HIO3 solution to it Note for advanced students you may assume the final volume equals the initial volume of the solution plus the volume of HIO3 solution added Round your answer to 2 decimal places pH 0 X S

For the process H O 1 1 bar 373 K H O g thermodynamic 1 bar 373 K the correct set of parameters is AG 0 AS ve a C AG ve AS 0 b d AG 0 AS ve 2007 3M AG ve AS ve

In a closed insulated container a liquid is stirred with a paddle to increase its temperature In this process which of the following is true CBSE PMT 2002 a AE W Q 0 c AE W 0 Q 0 For th action b AE 0 Q W 0 d AE Q 0 W 0

Calculate A H for the reaction BonREDMI NOTE 14 enthalpAQUAD CAMERA 1 11 H H L C C 30 0 The average bond enthalpies of various bonds are Bond C H 0 0 C O 499 HH 724 20 C 0 2H 0 H O H 460 C C 619

Mass and energy are conserved is demonstrated by MH CET 2 a First law of thermodynamics b Law of conservation of energy c Law of conservation of mass d Modified form of Ist law of thermodynamics

The rate of a certain reaction was studied at various temperatures The table shows temperature 7 and rate constant k data collected during the experiments Plot the data to answer the questions What is the value of the activation energy Ea for this reaction E kJ mol 1 What is the value of the pre exponential factor sometimes called the frequency factor A for this reaction A 8 1 T K 400 420 440 460 480 500 520 540 560 580 5 0 0000173 0 000127 0 000773 0 00403 0 0183 0 0738 0 267 0 879 2 66 7 43

For the reaction NH4Cl aq NH3 g HCl aq AG 61 4 kJ and AH 86 4 kJ at 316 K and 1 atm This reaction is reactant product favored under standard conditions at 316 K The entropy change for the reaction of 1 54 moles of NH4Cl aq at this temperature would J K

SECTION I A Write a note on physical signification of entropy Calculate change in entropy when 1 gm mole of two ideal gases mixed at 1 atmosphere isothermally R 1 987 cal mole degree Sit 7 7

Determine the amount of heat in KJ required to heat 36 g of liquid Ca at 834 C to 989 C Melting Point 851 C Boiling Point 1487 C Molar Heat Capacities Csolid 26 2 J mol C Cliquid 31 0 J mol C AH fusion 9 33 kJ mol AHvaporization 162 kJ mol

MEC KTG 2 D Relative Mat 127 Two tall buildings are 30 m apart The speed with which a 127 3 m 30 m fra 150 m furgant van fer fee if an 2 RR 27 5 m forga ball must be thrown horizontally from a window 150 m above the ground in one building so that it enters a window 27 5 m from the ground in the other building is 1 2 ms 2 6 ms 1 3 4 ms 4 8 ms falling vertically The speed of rain w 1 0 5 m s 128 Two stones are projected with the same speed but making 128 TRT I F 2 0 52 different angles with the horizontal Their ranges are equal If the angle of project 1 2 ms 2 6 ms 3 4 ms 48 ms Iro 10 30m 9 7 5 150 Class X Batectronics Modern Phys 97 5 1995 Gurukripa 32 To a stationary man at an angle 30 we forward with speed

39 Which among the following occurs in the given reaction 2PbO C2Pb CO2 A Lead is getting reduced B Lead dioxide is getting oxidized C Carbon is getting oxidized D Lead oxide is getting reduced

34 Arrange the following ecosystems in decreasing order of productivity Only one correct answer Review A Sugar cane field coral reef tropical rain forest estuary Coral reef estuary sugarcane field

denly put into neutral gear i e allowed to coast the ve driven at 20 m s on a level road is sud 13 2 kg locity decreases in the following manner 1 20 t S where t is the time in sec The deceleration of car at the instant its speed is 10m s is 1 1 4 m s 2 1 2 m s 3 1 m s 4 3 4 m s 20 a yov dx 20 m s MEC Electronics Modern Physics Vector 1 D Projectile s XIII Spartan Batch L0 20 ax 20 m s A car is moving uniformly on a road and appears t aran Berita for it ht fan V 3 1 m s 4 3 4 m s 20 248 itt et 44 second ame 10m s 1 1 4 m s 2 1 2 m s 20 20m s Lo LO 20 1 4 0

2 Enthalpy changes in chemical reactions from the data given below 2 g 12 2 HI AH 26 0 kJ 2 s H 12 HI AH 5 0 kJ 2 g AH sublimation of I can be obtained as A 31 kJ C 62 kJ B 62 kJ D 21 kJ

reactions C graphite 1 2O CO AH 110 5 kJ CO 1 2O CO AH 283 2 kJ the heat of reaction of C graphite O CO is 1 393 7 kJ 3 172 7 kJ 155 From the thermochemical 2 393 7 kJ 4 172 7 kJ TC0174

TC0176 58 If H g Cl g 2HCl g AH 44 kCal 2Na s 2HCl g 2NaCl s H g AH 152 kCal Then Na s 0 5 C1 g 1 108 kCal 3 98 kCal NaCl s A H 2 196 kCal 4 54 kCal

216 81m 150 90nz 6 595n328 412 kJ s lving Equations 1 through 3 simultaneously yields n 92 0 mol C H5OH s

ALLEN 128 The temperature of a 5 ml of strong acid increases by 5 C when 5 ml of a strong base is added to it If 10 ml of each are mixed temperature should increase by O 134

What will be the effect of adding 100 ml of 0 001 M HCl solution to 100 ml of a solution having 0 1 M HA The acid dissociation constant of HA is 10 5 a The degree of dissociation of HA will decrease but the pH of solution remains unchanged b The degree of dissociation of HA remains unchanged but the pH of solution decreases c Neither degree of dissociation nor pH of solution will change d The degree of dissociation as well as

1 108 kcal 3 98 kcal 2 196 kcal 4 54 kCal TC017 59 i S s 3 2 O g SO g 2x kl ii SO g 2O g SO g y kCal Calculate the heat of formation of SO 1 2x y 2 2x y 3 x y 4 2x y

32 The heat of combustion of C H C H and H are 1409 5 kJ 1558 3 kJ and 285 6 kJ The heat of hydrogenation of ethene is 1 136 8 kJ 3 273 6 kJ 2 13 68 kJ 4 1 368 kJ

31 The change in the enthalpy of NaOH HCI NaCl H O is called 1 Heat of neutralisation 2 Heat of reaction 3 Heat of hydration 4 Heat of solution 137 E 2 1 3 ion 20

0131 124 Heat of formation of CO is 94 0 kCal What would be the quantity of heat liberated when 3 g of graphite is burnt in excess of oxygen 2 2 35 kcal 4 31 20 1 23 5 kCal 3 90 Sl

on HEAT OF NEUTRALIZATION 125 The amount of heat liberated when one mole of NH OH reacts with one mole of HCl is 1 13 7 kCal 2 More than 13 7 kCal 4 Cannot be predicted 3 Less than 13 7 kCal 2 EXEP65

118 The following are the heats of reactions i AH of H O 68 3 kCal mol 1 AHomb of C H 337 2 kCal mol ii AHomb of C H 363 7 kCal mol Then heat change C H H CH is 1 716 1 kCal 3 41 8 kCal ession for the reaction 2 337 2 kCal 4 579 5 kCal

151 2CO Oa 2CO X kJ 2gl In the above equation X kJ refers to 1 Heat of formation of CO 2 Heat of vapourisation 3 Heat of reaction 4 Heat of sublimation

4 Can t be predicted CK0093 86 The rate of a chemical reaction doubles for every 10 C rise in temperature If the temp is increased by 60 C the rate of reaction increases by 1 20 times 2 32 times 3 64 times 4 128 times 94

CK0094 87 According to the arrhenius equation a straight line is to be obtained by plotting the logarithm of the rate constant of chemical reaction log k against 95 1 T 2 log T 3 T 4 log CK0095

Which of the following is INCORRECT statement A B C D In adiabatic expansion of an ideal gas temperature of system always decrease In isothermal expansion of an ideal gas temperature of a gas always remains constant In a reversible adiabatic compression of an ideal gas change in entropy of system is zero In an irreversible adiabatic compression of an ideal gas change in entropy of system is

79 The Gibbs free energy change of a reaction at 27 C is 26 kCal and its entropy change is 60 Cals K AH for the reaction is 1 44 kcals 3 34 kals 2 18 kCals 4 24 kcals TD0088

ctively the e reaction 4 41 2 TC0117 and carbon espectively noxide is HEAT OF COMBUSTION 111 According to equation CH 15 2 0 g 6CO g 3H O 0 AH 3264 4 kJ mol the energy evolved when 7 8 g benzene is burnt in air will be 1 163 22 kJ 2 32 64 kJ 3 3 264 kJ 4 326 4 kJ

1 E E 3 E E 2 E E 4 E 4E CK0088 1 At room temperature the reaction between NO and O to give NO is fast while that between CO and O is slow it is due to 1 CO is smaller in size than that of NO 2 CO is poisonous 3 The activation energy for the reaction 2NO O 2NO is less than 200 0 2C0 4 NO is poisonous AL KINETICS02 EXEP65