Thermodynamics - Class 11 Engineering Chemistry - Extra Questions

Total internal energy of a system can never be evaluated but the change in internal energy can be determined by 1st law of thermodynamics.
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Write mathematical equations of first law of thermodynamics for the following processes :
(a) Adiabatic process                 (b) Isochoric process



What is Gibb's Energy?



The thermal capacity of calorimeter system is $$17.7\ kJ$$ $${K}^{-1}$$. ($$R=8.313\ {mol}^{-1}{K}^{-1}$$) (only magnitude in nearest integer in kJ/mol)



For a given reaction, energy of activation for forward reaction $$(E_{af}) \: is \: 80kJ.mol^{-1} .\Delta H =-40kJ.mol^{-1}$$  for the reaction. A catalyst lowers $$E_{af} \: to \: 20 \: kJ.mol^{-1}$$ . Find out the ratio of energy of activation for reverse reaction before and after addition of catalyst.



First law of thermodynamics is not adequate in predicting the spontaneity of process.
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What is the relationship between $$\Delta G, \ \Delta H \ \& \Delta S$$?



Calculate $$\Delta { G }^{ o }$$ for the following reaction:
$$CO(g)+\cfrac { 1 }{ 2 } { O }_{ 2 }(g)\longrightarrow { CO }_{ 2 }(g);\Delta { H }^{ o }=-282.84kJ\quad $$
Given, $${ S }_{ { CO }_{ 2 } }^{ o }=213.8J{ K }^{ -1 }{ mol }^{ -1 },{ S }_{ CO(g) }^{ o }=197.9J{ K }^{ -1 }{ mol }^{ -1 },{ S }_{ { O }_{ 2 } }^{ o }=205.0J{ K }^{ -1 }{ mol }^{ -1 }$$



The standard enthalpy and entropy changes for the reaction in equilibrium for the forward direction are given below:
$$CO(g)+{ H }_{ 2 }O(g)\rightleftharpoons C{ O }_{ 2 }(g)+{ H }_{ 2 }(g)$$
$$\Delta { H }_{ 300K }^{ o }=-41.16kJ{ mol }^{ -1 }$$
$$\Delta { S }_{ 300K }^{ o }=-4.24\times { 10 }^{ -2 }kJ{ mol }^{ -1 }$$
$$\Delta { H }_{ 1200K }^{ o }=-32.93kJ{ mol }^{ -1 }$$
$$\Delta { S }_{ 1200K }^{ o }=-2.96\times { 10 }^{ -2 }kJ{ mol }^{ -1 }\quad $$
Calculate $${K}_{P}$$ at each temperature and predict the direction of reaction at $$300K$$ and $$1200K$$, when $${ P }_{ CO }={ P }_{ { CO }_{ 2 } }={ P }_{ { H }_{ 2 } }={ P }_{ { H }_{ 2 }O }=1$$ atm at initial state.



$${ C }_{ 2 }{ H }_{ 4 }+{ Cl }_{ 2 }\longrightarrow { C }_{ 2 }{ H }_{ 4 }{ Cl }_{ 2 }$$
$$\Delta H=-270.6kJ\quad { mol }^{ -1 };\Delta S=-139J{ K }^{ -1 }$$
(i) Is the reaction favoured by entropy, enthalpy both or none?
(ii) Find $$\Delta G$$ if $$T=300K$$



In a process 701 J of heat is absorbed by a system and 394 J of work is done by system. What is the change in internal energy for the process?



How much energy is required to change $$2\ Kg$$ of ice at $${0}^{0}C$$ into water at $${20}^{0}C$$? (specific latent of heat of fusion of water = $$3,34,000J/Kg$$, specific heat capacity of water = $${4200}\ {J}{Kg}^{-1}{K}^{-1}$$).



State and explain the first law of thermochemistry.



Law of conservation of energy is also known as ........



List I and List II contains four entries each. Entries of Column I are to be matched some entries of List II. One or more than one entries of List I may match with the same entry of List II.
List I lists the partial derivatives and List II lists the thermodynamic variable.



A slice of banana weighing 2.502 g was burnt in a bomb calorimeter producing a temperature rise of $$3.05^{\circ}C$$. The combustion of 0.316 g of benzoic acid in the same calorimeter produced a temperature rise of $$3.24^{\circ}C$$. The heat of combustion of benzoic acid at constant volume is $$-3227 \: kJ \: mol^{-1}$$. If the average banana mass is 125 g, the kilojoules  of energy can be obtained from 1 average banana is: (nearest integer value)



Calculate the enthalpy change for the reaction (only magnitude in nearest integer in kj/mol):
$$2C(s)+2{H}_{2}(g)+{O}_{2}(g)\longrightarrow {CH}_{3}{CO}_{2}H(l)$$



What are the characteristics of free energy $$(G)$$?



The enthalpy of combustion of glucose is $$-2808kJ\quad { mol }^{ -1 }$$ at $${ 25 }^{ o }C$$. How many grams do you need to consume. (Assume $$wt=62.5kg$$)
(a) to climb a flight of stairs rising through $$3M$$
(b) to climb a mountain of altitude $$3000M$$?
Assume $$25$$% of enthalpy can be converted to useful work.



A sample of $$0.16\ g\ CH_{4}$$ was subjected to the combustion at $$27^{o}C$$ in a bomb calorimeter. The temperature of the calorimeter. The temperature of the calorimeter system (including water) was found to rise by $$0.5^{o}C$$. Calculate the heat of combustion of methane at
(i) constant volume and
(ii) constant pressure. the thermal capacity of calorimeter system is $$17.0\ kJ\ K^{-1}$$ and $$R=8.314\ J\ K^{-1}\ mol^{-1}$$



The specific heats of iodine vapour and solid are $$0.031$$ and $$0.05$$ cals/g respectively. If heat of sublimation of iodine is $$24$$ cals/g at $${ 200 }^{  o }C$$.
Calculate its value at  $${ 250 }^{ o }C$$.



If 1.0 k cal of heat is added to 1.2 L of $$O_2$$ in a cylinder of constant pressure of 1 atm, the volume increases to 1.5 L. Calculate $$\Delta H$$ and $$\Delta U$$ of the process.



Give reasons : 
Thermodynamically an exothermic reaction is sometimes not spontaneous.



For the synthesis of ammonia at 300 K:$$N_2(g) +3H_2(g) \rightarrow 2NH_3(g)$$ 
Calculate the value of the $$\Delta G^0$$ in Kcal and give your answer in magnitude by using the following data:
                                                       $$N_2$$            $$H_2$$      $$NH_3$$ 
$$\Delta H^0_{f} (kcal/mole)$$                       0                0                   -10
$$S^0(Cal/K-mole)$$                      40                   30                 45



The heat of solution of $$NH_{4}NO_{3}$$ in water was determined by measuring the amount of electrical work needed to compensate for the cooling which would otherwise occur when the salt dissolves. After the $$NH_{4}NO_{3}$$ was added to the water, electrical energy was provided by the passage of current through a resistance coil until the temperature of the solution reached the value it had prior to the addition of salt. In a typical experiment, $$4.4\ g$$ of $$NH_{4}NO_{3}$$ was added to $$200\ g$$ water. A current of $$0.75$$ ampere was provided through the heater coil, and the voltage across the terminals was $$6.0\ V$$. The current was applied for $$5.2$$ minute. Calculate $$\Delta H$$ for the solution of $$1.0$$ mole $$NH_{4}NO_{3}$$ in enough water to give the same concentration as was attained in the above experiment.



Given below are some standard heats of reaction;
(a) Heat of formation of water $$=-68.3\ kcal$$
(b) Heat of combustion of acetylene $$=-310.6\ kcal$$
(c) Heat of combustion of ethylene $$=-337.2\ kcal$$
Calculate the heat of reaction for the hydrogenation of acetylene at constant volume at $$25^oC.$$



Calculate pH at which the following conversion (reaction) will be at equilibrium in basic medium $$I_2(s) \rightarrow I^-(aq)+IO_3^-(aq)$$ when the equilibrium concentrations at 300K are $$ [I^-]=0.10 M$$ and $$ [IO_3^-]=0.10 M$$ 
[Given that $$\Delta G ^0_f(I^-,aq)=-50 kJ/mole, \Delta G^0_f(IO_3^-,aq)=-123.5 kJ/mole, \Delta G^0_f(H_2O,l)=-233kJ/mole$$
$$\Delta G^0_f(OH^-,aq)=-150kJ/mole$$ ideal gas constant=$$R=\dfrac{25}{3}Jmole^{-1}K^{-1}, log_e10=2.3$$]



$$\alpha- D$$ glucose undergoes muta rotation to $$β-D$$ glucose in aqueous solution. If at $$298 K$$ there is $$60\%$$ conversion. Calculate $$\Delta G^o$$ for the reaction.



What is specific heat capacity?



Class 11 Engineering Chemistry Extra Questions