Energetics Questions and Answers

d 22 4 litre 38 The heat evolved during the combustion of 112 litre o water gas mixture of equal volume of H2 and CO is AH 241 8 kJ H g O g H O g CO g O g CO g AH 283 kJ

HT0051 6 The temperature of hot and cold end of a 20 cm long rod in thermal steady state are at 100 C and 20 C respectively Temperature at the centre o the rod is 1 50 C 3 40 C 2 60 4 30 C HT0055

45 Two metal rods 1 2 of same length have same temperature difference between their ends their thermal conductivities are K K and cross sectional areas A A respectively What is required condition for same rate of heat conduction in them 1 K K 3 K K A A 2 K A K A K K 4 50 If th ca 10 gra 1 3 51 Th 1

HT0067 RADIATION 2 A spherical body of area A and emissivity e 0 6 is kept inside a black body What is the rate at which energy is radiated per second at temperature T 1 0 6 G AT4 2 0 4 0 AT AT 3 0 8G AT 4 1 0

83 Solar constant for earth is 2 cal min cm if distance of mercury from sun is 0 4 times than distance of earth from sun then solar constant for mercury will be 1 12 5 cal min cm 2 25 cal min cm 3 0 32 cal min cm

3 CH40 g C3H6 g 3 H2O g Enthalpy change of reaction at 300 C A H 101 18 kJ mol Entropy change of reaction at 300 C A S 42 40 J K mol 1 Using the above information calculate the Gibbs free energy change A G for this reaction at 300 C Show your working Based on the results of your calculations is this reaction spontaneous at 300 C Clearly explain your reasoning

EXERCISE I Conceptual Questions TEMPERATURE THERMAL EXPANSION 1 At what temperature does the temperature in Celsius and Fahrenheit equalise 1 40 2 40 3 36 6 4 38 6 L t

HT0016 21 1 kg of ice at 10 C is mixed with 4 4 kg of water at 30 C The final temperature of mixture is specific heat of ice 2100 J kg k 1 2 3 C 2 4 4 C 3 5 3 C 4 8 7 C HT0023 ENGMODULE 0301 THERMAL PHYS

Kinetic data for hydrolysis of a 0 3 M solution of ethyl acetate in presence of HCI as catalyst is given in the following table A constant volume of reaction mixture is taken at different time and titrated against standard alkali solution at different time Time min 0 10 Vol of Alkali ml 25 00 28 00 40 00 If the rate law is given by rate k Ester H where H is a catalyst find the rate in M min of ester hydrolysis in a solution which is 0 1 M each in ester and acid HCI Use In 0 225 Report your answer by multiplying actual answer by 105

AG kJ mol of O 100 200 300 400 500 600 700 800 0 900 1000 1100 1200 273 K 2Fe 0 2FeO 200 0 2C0 2Zn O 2ZnO 4Cu O 2Cu 0 673 K 4 3A1 O 2 3ALO 2Mg 0 2MgO 1073 K 2C 0 2CO C O CO Temperature A 1473 K 1873 K P 2273 K Does this graph mean that mg can easily get oxidized it is having very low delta g 12 0

FL0048 19 Water flows through a frictionless duct with a cross section varying as shown in figure Pressure P at points along the axis is represented by 1 3 P 2 4 v 54 55 56

Read More The correct order of energy of orbital is OE2 K E2 Na E2s Li E2s H O E2s H E2s Li E2s Na E2s K O E2s Li E2s H E2s K E2s Na

Calculate DH and DS when a 1kg copper bar at 100 C is introduced into an insulated container maintained at 1 atm of pressure containing 2 kg of water at 0 C Cp Cu 0 1 cal K gram and H20 1 1 cal K gram

3 The heat of combustion of maltose at constant volume in the above question if water vapour are not condensed 1 1350 kcal mol 2 1343 kcal mol 3 1370 kcal mol 4 1400 kcal mol Comprehension III In a fuel cell methanol is used as a fuel and O is used as oxidizer The standard enthalpy of combustion of methanol is 726 kJ mol The standard free energies of formation of CH OH I CO g and H O l are 166 3 394 4 and 237 1 kJ mol respectively Choose the correct answer 1 The standard free energy change of the reaction will be 1 597 8 kJ mol 3 465 2 kJ mol 3 2 The efficiency of the fuel cell will be 2 66 2 4 85 1 energy change of the ce 1 96 7 3 41 3 The standard internal reaction will be 2 298 9 kJ mol 4 702 3 kJ mol 1 727 24 kJ mol 3 728 48 kJ mol 2 724 76 kJ mol 1 4 723 42 kJ mol

26 The r m s velocity of hydrogen is times the r m s velocity of nitrogen If T is the temperature of gas then A T H T N B T H T N C T H T N D TH TN 4 C r

45 When a compressed gas is allowed to expand through a porous plug at a temperature above its inversion temperature there is A A fall in temperature B A rise in temperature C Neither a fall or nor temperature D A fall in temperature first followed by a rise in

Some homes that use baseboard heating use copper tubing Hot water runs through and heats the copper tubing which in turn heats aluminum fins It is actually the aluminum fins that heat the air rising through the fins How much energy would it take to heat is section of the copper tubing that weighs about 585 0 g from 13 60 Cto 25 00 C Copper has a specific heat of 0 3m J g C Express your answer to four significant figures View Available Hint s VAX SING

An unknown substance has a mass of 14 9 g When the substance absorbs 1 341x10 J of heat the temperature of the substance is raised from 25 0 C to 45 0 C What is the most likely identity of the substance View Available Hint s ethanol water aluminum silver iron copper

A certain mass of ideal gas absorbs 80kJ heat and gas expanded from 2L to 10L against a constant pressure of 25 bar then AU for this process in kJ mole is x 1bar L 100J X then 10

From the following bond energies H H bond energy 420 kJ mol 1 C C bond energy 601 kJ mol 1 C C bond energy 340 kJ mol C H bond energy 425 kJ mol 1 Enthalpy for the reaction C H 2H C H6 1 599 kJ mol 1 3 625 kJ mol 1 2 580 kJ mot 4 325 kJ mott

For the reaction C s graphite O g CO g AG 394 4 kJ and AS 2 9 1 K at 321 K and I atm This reaction is reactant product favored under standard conditions at 321 K The standard enthalpy change for the reaction of 1 91 moles of C s graphite at this temperature would be

Which of the following are physical changes i Melting of iron metal ii Rusting of iron iii Bending of an iron rod iv Drawing a wire of iron metal Options i ii and iii i ii and iv i iii and iv ii iii and iv

Question Number 155 Question Id 8135612075 Question Type MCQ Display Quest Number Yes Is Question Mandatory No Single Line Question Option No Option Orientation Vertical Standard enthalpy of vaporization AH ep for water at 100 C is 40 66 kmol The inte of vaporization of water at 100 C in kJ mol is Assume water vapor to be ideal gas 100 C og 50 pora ob po0 Door Dend 40 66 kl mol 100 C og 30 aus s by ks mol 6 50 ebet eso pront ang south of ded Options 1 43 76 2 40 66 3 37 56 egy like a 43 76

Question Number 145 Question Id 8135612065 Question Type MCQ Display Question Number Yes Is Question Mandatory No Single Line Question Option No Option Orientation Vertical BT2 g Calculate the boiling point of bromine Given AH and AS values for Br2 1 are 30 91 kJ mol and 93 2 J K mol respectively Assume AH and AS do not change with temperature Br2 1 93 2 J K mol ove Br Jun La Boda Dowod Options 1 331 6 K 2 300 K 3 298 K B12 9 05 AH Boat As Deuser Jour 30 91 k J mol 1 38adu ood AH 80 AS 4 350 K

For the reaction 2HBr g Cl g AH 81 1 kJ and AS 1 2 J K The standard free energy change for the reaction of 1 95 moles of HBr g at 257 K I atm would be This reaction is reactant product favored under standard conditions at 257 K Assume that AH and AS are independent of temperature 2HCl g Br g

Question Number 122 Question Id 8135612202 Question Type MCQ Display Questio Number Yes Is Question Mandatory No Single Line Question Option No Option Orientation Vertical Calculate the change in enthalpy for the reaction 2H O2 1 2H 0 1 02 g Given the heats of formation of H 0 and H 02 1 are 188 kJ mol and 286 kJ mol respectively 1 2H 02 1 2H 0 1 O2 g Bojes doar dy ra chocod H 0 1 380 H 02 1 e dos ago Devsev Sorr 188 kJ mol 58a 286 kJ mol rangwand Options 196 kJ mol 1 1 2 948 kJ mol 1 3 4 196 kJ mol 948 kJ mol 1 AP EAMCET 2020 AP EAMCET 2020

a certain reaction at 25 0 C the value of K is 0 34 At 50 C the value of K is 012 this mean that the reaction is Endothermic O None of all O Exothermic

For the conversion of oxygen to ozone 302 203 the correct relation for change in enthalpy and change in entropy is Only one correct answer A AH 0 AS 0 B AH 0 AS 0 C AH 0 AS 0 D AH 0 AS 0

1 10 A Camot engine having an efficiency of as heat engine is used as a refrigerator If the work done on the system is 10 J the amount of energy absorbed from the reservoir at lower temperature is NEET 2017 1 1 J m 99 2 90 J 4 100

30 A heat engine rejects 600 cal to the sink at 27 C Amount of work done by the engine will be Temperature of source is 227 C J 4 2 J cal 1 1680 J 2 840 J 3 2520 J 4 None of these

6 Neon gas of a given mass expands isothermally to double volume What should be the further fractional decrease in pressure so that the gas when adiabatically compressed from that state reaches the original state 7 1 1 2 20 3 213 When 1 2 1 3 ta 4 320 at 0 C molt at 0 C

1 1 3 213 2 4 320 When 1 kg of ice at 0 C melts to water at 0 C the resulting change in its entropy taking latent heat of ice to be 80 cal C is 1 293 cal K 2 273 cal K 3 8 x 10 cal K

2 2 15 Figure shows the adiabatic curve on a log T and log V scale performed on ideal gas The gas is log T 5 4 3 log V 1 Monatomic 2 Diatomic 3 Polyatomic 4 Mixture of monatomic and diatomic

322 Thermodynamics 29 Efficiency of a heat engine working between a given source and sink is 0 5 Coefficient of performance of the refrigerator working between the same source and the sink will be 2 0 5 4 2 1 1 3 1 5

Question Number 131 Question Id 7512365571 Question Type MCQ Option Shuffling Yes Display Question Number Yes Single Line Question Option No Option Orientation Vertical When 0 8 g of glucose CH O was burnt in a bomb calorimeter according to the following equation the temperature raise is found to be 2 K at 1 atm C6H12O6 s 602 g 6CO2 g 6H 0 1 If the heat capacity of the bomb calorimeter is 6 8 kJ K the approximate enthalpy change of the reaction in kJ mol is Molar mass of glucose 180 g mol 0 8 gs CH 2O6 5 od 350555 5550 m Sod 500 500 1 atm 5 de 2 Km gow358 6CO2 6H O s C6H 2O6 602 35055 D 6 8 kJK 55er do 180 g mol Options 2 3 2 10 1 10 6 8 10 dogs Joard kJ mol

14 The variation of pressure P with volume V for an ideal monatomic gas during an adiabatic process is shown in figure At point A the magnitude of rate of change of pressure with volume is P4 1 3 3 P 5 3 P 2 3 P O 2 V 2 4 V 5 P 3 5 P 2 C 2 3 4 18 If ab ge

The combustion of one mole of benzene takes place at 298 K and 1 atm After combustion CO g and H O 1 are produced and 3267 0 kJ of heat is liberated Calculate the standard enthalpy of formation A H of benzene Standard enthalpies of formation of CO g and H O 1 are 393 5 kJ mol and 285 83 kJ mol respectively

11 2 points Compare a high energy gamma ray to a low energy radio wave What can be said about the relative speeds of these different wavelengths of electromagnetic radiation Choose one correct answer a the radio wave travels faster c they both travel at the same speed b the gamma ray travels faster d it is not possible to determine

The molecular weight of Carbone dioxide is CO is 44 kg mol In an experiment the value of y was found to be 1 3 Assuming that CO is a perfect gas Calculate a the gas constant and the specific heat at constant pressure and volume b The increase of internal energy and enthalpy per 8 kg of Carbone dioxide with inlet Temperature 77 C and outlet temperature 45 C

20 9 g of sodium nitrate is added to a coffee cup calorimeter The calorimeter initially contained 150 0 mL of 25 0 C distilled water The specific heat of the solution is 4 22 J g C The enthalpy of dissolution for sodium nitrate is 20 50 kJ mol What is the final temperature after stirring and reaching thermal equilibrium 32 C 7 C 15 C 18 C

c 40K 68 50 g of oxygen at NTP is compressed adiabaticall to a pressure of 5 atmosphere The work done on the gas if y 1 4 and R 8 31 1 mol K is a 5173 b 1131 J c 1364 d 5673

The temperature of two identical gases is increased from the same initial temperature to the same final temperature Reversible processes are used For gas A the process is carried out at constant volume while for gas B it is carried out at constant pressure Is the change in entropy for A greater than for B Why Show detailed explanation in terms of its pressure temperature and volume

Which of the following processes are accompanied by increase of entrop diodicame i Dissolution of iodine in a solvent 1 s I aq nelave ii HCl is added to AgNO and a precipitate of AgCl is obtained 3 ribiniw mstate to one or to heq se vpisns iii A partition is removed to allow two gases to mix ustration 24 eu oini bahevrop sd di x

If 8 6 g of solid NaOH is added to 1 00 L of water at 25 0 C in a constant pressure calorimeter what will be the final temperature of the solution Assume the density of final solution is 1 05 g mL NaOH s NaOH aq AH 43 kJ

Using the data all values are in kcal per mole at 25 C given below calculate the summation of bond energy in kcal mole of C C and C H bonds is x then value of x 80 Given AH combustion ethane 372 AH combustion propane 530 AH for C graphite C g 172 Bond energy of H H 104 AH of H O 68 1 AH of CO g 94

One mol of an ideal gas at 300 K is expanded isothermally from an initial volume of 1 litre to The AE for the process is R 2 Cal K mol 1 163 7 Cal 3 9 L atm 2 1381 1 Cal 4 Zero

Q 3 MODERATE 67 6 kcal 36 5 kcal O 36 5 kcal 4 1 The heat of formations of CO g and CO g are 26 4 kcal and 94 0 kcal respectively The heat of combustion of carbon monoxide will be 465 kcal 00 27 O

a to state b shown in both PV and TS diagram below What is the change in internal energy from a to b In10 2 3 10 P bar V L 8300 J O 3700 J O 3700 J 10 300 K T 30 S J K 50

Sodium reacts violently with water according to the equation 2 Na s 2 H O l 2 NaOH aq H g The resulting solution has a higher temperature than the water prior to the addition of sodium What are the signs of AH and AS for this reaction A AH is negative and AS is negative B AHO is negative and AS is positive C AH is positive and AS is negative D AH is positive and AS is positive OA OB OC O D K

3 points Calculate the enthalpy change for the reaction given below using the thermodynamic table below 4C H5NO 90 8CO 10H O 2N Compound C H5NO CO H O AH kJ mol 528 393 5 241 8