Energetics Questions and Answers

3 100 mL of 0 05 M CuSO4 aq solution was electrolyzed using inert electrodes by passing current till the pH of the resulting solution was 2 The solution after electrolysis was neutralized and then treated with excess KI and formed 1 titrated with 0 04 M Na S O3 Calculate the required volume in mL of Na S O3 1 112 5 mL 2 100 mL 3 125 ml 4 None of these

2 O For the reaction at 25 C X 04 1 2XO g AH 2 1 Kcal and AS 20 cal K The reaction would be 1 Spontaneous 2 Non spontaneous 3 At equilibrium 4 Unpredictable For the reaction 298 K 2A B C 70 4 n 3 1 1 m 1 s 25 C X 04 1 2XO g 31 3 AH 2 1 Kcal AS 20 cal K 1 Fad 2 3 3 4 71 298 KT 2A B C

24 Bond energies in kcal mol of different types of bonds have been given as C C bond 40 H H 104 and C H 87 c c C C H H cc HH Heat of hydrogenation of the above reaction is a 57 kcal mol b 57 kcal mol c 30 kcal mol d 30 kcal mol

a afe 1 AH is ve AS is ve AH 2 AH is ve AS is ve 3 AH is ve AS is ve 4 AH is ve AS is ve 3 AH is ve AS is ve 4 AHTS ve AS is ve 17 The enthalpy change of which reaction corresponds to 47 for fun after AH for Na Co s at 298 K AH fe but AH TAS 3 1 2Na s C s O g Na CO s 2 Na O s CO g Na CO s 3 2Na aq CO aq Na CO s 4 2Na aq 2OH aq CO aq Na CO s H O Which of the following is 3 112Na s C s O g 2 Na O s CO g Na Cr 3 2Na aq CO aq 0 300

4 90 For given following equations and AH values determine 90 the enthalpy of reaction at 298 K for the reaction C H g 6F g 2CF4 g 4HF g H g F g 2HF g AH 537 kJ C s 2F g CF4 9 AH2 680 kJ 2C s 2H g C H 9 AH 52 kJ 1 1165 2 2486 3 1165 4 2486 hld HR 9 12 fuff 298 K C H g 6F g 2CF g 4HF g H g F g 2HF g AH 537 kJ C s 2F g CF 9 AH 680 kJ 2C s 2H g CH g AH 52 kJ 1 1165 2 2486 3 1165 4 2486

Part III Calculating the Heat Associated with Phase Changes Physical Constants for Acetone Melting Point 94 7 C Boiling Point 56 1 C AHvap 31 3 kJ mol AH 5 7 kJ mol Molar Heat Capacity of liquid acetone is 125 J mol K Molar Heat Capacity of solid acetone is 96 J mol K 1 Calculate the energy required to heat 30 g of solid acetone C H O from 100 0 C to 42 0 C 2 Is heat released or absorbed in this process How can you tell 3 How would the amount of heat associated with this process change if only 15 grams was

ideal gas subjected to expansion against 1 mole of monoatomic irreversible adiabatic constant external pressure of 1 atm starting from initial pressure of 5 atm and initial temperature of 300 K till the final pressure is 2 atm What is the magnitude of work done in cal in the process take R 2 cal mol K

Which of the following relation is correct regarding reversible adiabatic process T V T V P V PfVf T V 1 T V 1 P V P V hr

Spartan Batch PCB 1 68 The heat of neutralisation for strong acid strong base 68 2 3 ETA ARIFIER forming 2 moles of water is 1 2 57 1 kJ 2 57 1 kJ 57 1 3 kJ 2 4 Strong acid and strong base will not undergo neutralisation 34 1 2 57 1 kJ 2 57 1 kJ 57 1 2 1 3 4 GRAFICZY I MI kJ

Consider a mixture of air and gasoline vapour in a cylinder with a piston The original volume is 40 cm If combustion of this mixture releases 950J of energy to what volume will the gas in L expands against a constant pressure of 5 bar if all the energy of combustion is converted into work to push back piston monostomic

88 Heat of formation of ethane is energies of H H C H and C C bonds are 104 18 99 and 80 kcal Than calculate heat of atomisation of graphite 1 171 kcal Ang 19 4 2 273 kcal 3 71 kcal 4 90 kcal 19 46 kcal and bond 88 19 46 kcal a H H C He The arbital J HINDI04 18 19 41 104 18 2 5 at 1 171 kcal 2 273 kcal 3 71 kcal 4 90 kcal 104 18 99 80 kcal a

For which of the following reaction AH AU CaCO3 s CaO s CO g N g 3 H g 2 NH3 g CH4 g 2 O g CO g 2 H O 1 H g 1 g 2 HI g hr

For given following equations and AH values determine the enthalpy of reaction at 298 K for the reaction C H4 g 6F2 g 2CF4 g 4HF g H g F2 g 2HF g AH 537 kJ C s 2F2 g CF4 g AH 680 kJ 2C s 2H g C H4 g AH 52 kJ A 1165

An imaginary place in three steps X A AH 91 B A AH 92 B Y AH 93 If Hess law is applicable then the heat of the reaction X Y is reaction X Y takes A 91 92 93 C 92 93 91 91 92 93 Correct Answer

The value of AH in kJ for the reaction will be CS2 1 4NOCI g CCl4 1 2SO g 2N g if AH CS x AH NOCI y AH f CCl4 z AH SO r A B C x 4y z 2r r z 4y x 2r z 4y x

A gas is allowed to expand in a well insulated container against a constant external pressure of 2 5 atm from an initial volume of 2 50 L to a final volume of 4 50 L The change in internal energy AU of the gas in joules will be 1 500 J 3 505 J 2 505 J 4 1136 25 J

What is the wavelength of light emitted when the electron in a hydrogen atom undergoes a transition from energy level n 4 to n 2 486 nm 91 1 nm 678 nm 289 nm

3 3 An ideal gas expands isothermally from 10 3 m to 10 2 m at 300 K against a constant pressure of 105 N m 2 The work done on the gas is a 270 kJ 900 kJ I for b 900 J d 900 kJ Odisha NEET 2019

A schematic representation of enthalpy changes for the C graphite O g CO g reaction is given below The missing value is A B Cgraphite O g T 393 5 KJ CO g 10 5 kJ 11 5 kJ CO g 1 2O g 283 0kJ

The q value and work done in isothermal reversible expansion of one mole of an ideal gas from initial pressure of 1 bar to final pressure of 0 1 bar at constant temperature 273 K are 5 22 kJ 5 22 kJ 5 22 kJ 5 22 kj

The bond enthalpies of H X and HX are in the ratio of 2 1 2 If enthalpy of formation of HX is 50 kJ mol the bond enthalpy of X is A B C 100 kJ mol 1 200 kJ mol 1 300 kJ mol 1 Correct Answer

neet prep CH CH NH 129 H IV 1 2 and 4 2 2 and 3 3 2 3 and 4 4 Only 2 High Yielding Test Series Full Test 2 converted to Given HCOOH 1 22 g cc 1 0 0185 2 0 0073 3 0 074 4 0 037 CH CH NH NH The value of K for self ionization of formic acid is 10 4 at room temperature What percentage of formic acid is formate ion Contact Number 9667591930 8527521718 130 The azeotropic mixture of water and ethanol boils at 78 15 C When this mixture is distilled it is possible to obtain 1 pure H O 2 pure C H OH 3 pure H O as well as pure C HOH 4 neither H O nor C H5OH in their pure state 131 The net work done for an ideal gas is given as 1 3PV 2 3PV 3 PV 4 Zero 132 p v 133 Y 4p 3v Aluminium reacts with concentrated HCI and concentrated NaOH to liberate the Z p 3v gases respectively 1 H and H 2 0 and O 3 0 and H 4 H and O 2 1 3 2 4 0 Using MO theory predict which of the following species has the shortest bond length 1 0 2 0 3 02 4 0 2 134 The oxidation state of sodium in sodium amalgam is 1 1 135 Lactic acid on oxidation by alkaline potassium permanganate gives

3 Enthalpy of sublimation of iodine is 24 cal g at 200 C If specific heat of I s and 1 I vap are 0 055 and 0 031 cal g K respectively then enthalpy of sublimation of iodine at 250 C in cal gis JEE Main 2019 12 April Shift 1 a 2 85 c 22 8 b 5 7 d 11 4

4 0 50 A 69 Consider the following conversions i O g e O g AH ii F g e F g AH iii Cl g e Cl g AH3 iv O g e O g AH4 Then according to given information the incorrect statements is 1 AH is more negative than AH and AH 2 AH is less negative than AH 3 AH AH and AH are negative whereas AH is positive 4 AH and AH are negative whereas AH and AH are positive

AH for CaCO3 s CaO s CO2 g is 176 kJ mol 1 at 1240 K The AU for the change is equal to A 160 kJ B 165 6 kJ C 186 3 kJ D 180 0 kJ For a chemical reaction 2A g 5B g at 27 C the difference Then the ratio X R A Zero C 5 100 2A B g 5 between AH and A E is X B Unity D 1 5 x 103

If burning 15 g of C H6 in excess of air gives x kJ heat energy then enthalpy of combustion of ethane is 15 x kJ mol 1 30 x kJ mol 1 2 x kJ mol 1

Triad I N O Na Triad II N C 0 1 O Choose the species of lowest IP from triad I and highest IP from triad II respectively N 0 B Na C C N N D O C The correct values of ionization energies inkl mot of Ra Na Ha INE

K Which ionisation potential IP in the following equations involves the greatest ammount of energy A K K e P Lit Ca e Li 2 e C Fe Fet e D Cat The t LOS QU

61 180 Standard molar enthalpy of formation at 298 K is zero for Br 1 Smonoclinic H O 1 Mark for Review 03 g

200 0 g of metal specific heat 0 440 at 150 C was placed in 1 00 L of water at 25 0 C What is the final temperature of the nickel water mixture density of water 1g mL specific heat of water 4 184 J g C I 51 3 C II 26 3 C III 27 6 C IV 35 8 C V 62 5 C 22 49

JIUS 1 4 2 6 3 8 4 unpredictable If the radius of K and F are 133 pm and 136 pm respectively the distance between K and Fin 1 269 pm 2 134 5 pm 3 136 pm 4 3 pm In zinc blende structure the coordination number of Zn ion is 216 4 8

For which of the following pair heat of neutralisation is less than 13 7 kcal HCI KOH CH3COOH NaOH HCI NaOH H SO4 NaOH

The heat of neutralization will be highest for which of the following neutralization reactions 1 NH OH and HCI 2 NH OH and CH COOH 4 NaOH and CH COOH 3 NaOH and HCI What is true about rate of reaction 1 Decreases with increase in temperature

4 dic quis ant faut T equation is T d 38 For an exothermic reaction following two steps are 38 fait fuffo fa fafed involved Step 1 A B I Step 2 I AB Which of the following graphs correctly represent this reaction 1 A B Reaction coordinate AB im imium im A B Reaction coordinate AB 4 A B A B In Arrhenious AB slow fast Reaction coordinate Reaction coordinate Step 1 Step 2 AB A B I I AB A B Potential energy JA A B AB Reaction coordinate AB Reaction coordinate EFTAT 1 as weit wegd all Reaction coordinate k A B AB Reaction coordinate

SINGLE CORRECT QUESTIONS 1 Temperature of one mole of helium gas is increased by 1 C hence increases in internal energ A 7 cal B 5 cal C 3 5 cal D 3 cal Which has maximum internal onoray 2

Calculate AG rxn 6H 0 1 6 CO g 2C H 1 80 g given that AG CO g 394 6 kJ mol AG H O I 237 2 kJ mol and AG f C3H O I 154 5 kJ mol Select one 3481 8 KJ 1740 9 kJ 3481 8 kJ 1740 9 kJ

Q2A 10 mark A container filled with 35 kg of liquid water at 90 C is placed in a 90 m3 room that is initially at 14 C Thermal equilibrium is established after a while as a result of heat transfer between the water and the air in the room Using constant specific heats determine the entropy generation Assume the room is well sealed and heavily insulated

A carnot engine has a cycle as given in figure If W and W represent work done by one mole of monoatomic and diatomic gas respectively in the complete cyclic process then W calculate NARAYANA GROUP 4T Ans 3 V To 2 64V

The correct order of temperature of a real gas is 1 Boyle s temperature II Critical temperature III Inversion temperature 1 III I II 2 I II III 3 II 1 III 4 I III II

An ideal gas absorbs 2000 cals of heat from a heat reservoir and does mechanical work equivalent 4200 J The change in internal energy of the gas is 1 3000 cals 2 2000 cals 3 1500 cals 4 1000 cals

3 1 mole of NO and 2 moles of CO are enclosed in a one litre vessel to attain the following equilibrium NO CO NO CO It was estimated that at the equilibrium 25 of initial amount of CO is consumed The equilibrium constant K is 1 1 3 114 2 1 2 4 1 3

The heat of combustion of carbon to CO is 393 5 KJ mol The heat released upon the formation of 35 2 g of CO from carbon and oxygen gas is ne ch 1 315 KJ of 2 315 KJ 3 630 KJ an 4 630 KJ

The enthalpy of neutralization of HCN by NaOH is 12 13 kJ mol The enthalpy of ionisation of HCN will be 1 45 07 kJ 2 4 310 kJ 3 451 9 kJ 4 33 77 kJ

The activation energies of the forward and backward reactions in the case of a chemical reaction are 30 5 and 45 4 kJ mol respectively The reaction is 1 Exothermic 2 Endothermic 3 Neither exothermic nor endothermic 4 Independent of temperature

3 The blue colour changes to brown on standing 4 In concentrated solution blue colour changes to bronze and becomes diamagnetic One mole of ethanol is produced reacting graphite H and O together The standard enthalpy formation is 277 7kJmol Calculate the standard enthalpy of the reaction when 4 moles of graph is involved 1 277 7kJ mol 2 555 4kJ mol 3 138 85kJ mol 4 69 42kJ mol

Use Hess s Law to calculate the enthalpy change for the reaction WO3 s 3H2 g W s 3H O g from the following data 2W s 302 g 2WO3 s AH 1785 4 kJ 2H2 g O2 g 2H O g AH 457 84 kJ A 252 9 kJ B 205 9 kJ O C 125 9 kJ D 364 9 kJ

The activation energies for forward and backward reaction in a chemical reaction are 20 5 and 55 5 kJ mol respectively The reaction is O Exothermic O Endothermic O Neither exothermic nor endothermic O Independent of temperature

of the following expressions is true 1 H CO g 1 AH CO2 g 2 1 2 AH CO g AH C graphite 2 1 3 AH CO g AH CO g AH 0 9 2 AH O2 g comb 4 AH CO g AH C graphite A Homb CO g

The half life for the first order reaction is 69 s What time it will require to complete 80 of the reaction log 5 0 6990 Question Type Single Correct Type 1 2 3 160 S 69 s 124 S

3 It loses water when exposed to air 4 It has a high melting point An element P has atomic number 56 What will be the formula of its halide 1 PX 2 PX PX 3 4 P X3