Recent questions tagged thermodynamics

For a natural process in any isolated system

asked Mar 15, 2014 by thanvigandhi_1

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What is correct about the expression -$ P \Delta V$?

asked Mar 15, 2014 by thanvigandhi_1

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“The entropy of a perfect crystal at absolute zero is zero”. The statement corresponds to which law of thermodynamics

asked Mar 15, 2014 by thanvigandhi_1

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A process is spontaneous at all temperatures, if

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For which of the following process, $ \Delta S_{total} \: is\: < 0$,

asked Mar 15, 2014 by thanvigandhi_1

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For a reversible process at equilibrium, the entropy change $ \Delta S$ is given by

asked Mar 15, 2014 by thanvigandhi_1

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Which of the following is zero during adiabatic expansion of gas?

asked Mar 15, 2014 by thanvigandhi_1

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The absolute entropy of a free element

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A minus sign of the free energy change denotes that

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Which of the following relations is not correct?

asked Mar 15, 2014 by thanvigandhi_1

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Which of the following is not spontaneous?

asked Mar 15, 2014 by thanvigandhi_1

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When a solid melts, there is

asked Mar 15, 2014 by thanvigandhi_1

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For an exothermic reaction, which of the following is always $ < 0$

asked Mar 15, 2014 by thanvigandhi_1

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A circuit is made as shown --- The circuit contains a component made of bimetallic strip . If the temperature is increased , will the bulb glow ? ( Assume the emf of battery is enough to light the bulb )

asked Mar 15, 2014 by yamini.v

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If two rods of length L and 2L having coefficients of linear expansion $\;\alpha\;$ & $\;2 \alpha\;$ respectively are connected such that length becomes 3L ,The average coefficient of linear expansion of the composite rod equals ---

asked Mar 15, 2014 by yamini.v

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Rods of equal length & equal cross - section are arranged as shown - The thermal conductivity of the rods are written correspondingly . The equivalent thermal conductivity of the system is -

asked Mar 15, 2014 by yamini.v

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Figure shows the arrangement , gas is thermally insulated . Having pressure $\;p_{g}\;$ ( greater than atmospheric pressure $\;p_{a}\;$ ) . Spring of force constant k is initially unstretched . Position of mass m & area S is friction less and in equilibrium position , it rises up a distance $\;x_{0}\;$ , then -

asked Mar 15, 2014 by yamini.v

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$30\; gm$ ice at $\;-20^{0}C\;$ is mixed with $20\; gm$ water at $\;90^{0}C\;$. Find the final composition and temperature of mixture . (Latent Heat of fusion $80\; cal /gm$ )

asked Mar 15, 2014 by yamini.v

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Calculate the entropy change for the reaction \[\] $CO(g) + \large\frac{1}{2}$ $O_2(g) \rightarrow CO_2(g);\: \: \: \: \: \Delta S^o_{CO2} = 213.6\: J/Kmol, \Delta S^o_{CO }= 197.6\: J/Kmol, \Delta S^o_{O2} = 205.03 \: J/Kmol$

asked Mar 13, 2014 by thanvigandhi_1

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The equilibrium constant for a reaction\[\] $CO_2(g) + H_2(g) \rightleftharpoons CO(g) + H_2O(g) \: is \: 73$.\[\] Calculate the value of standard free energy change.

asked Mar 13, 2014 by thanvigandhi_1

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Calculate the standard free energy change, $ \Delta G^o$ for the reaction \[\] $H_2(g) + I_2(g) \rightarrow 2HI(g)$ \[\] Given that the standard enthalpy change and the standard entropy change for the reaction are $52 \: kJ\: and\: 165.2 \: J/K$ respectively.

asked Mar 13, 2014 by thanvigandhi_1

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Heat is supplied to a gas at constant pressure , the ratio $\; \bigtriangleup Q : \bigtriangleup u : \bigtriangleup W\;$ depends on

asked Mar 13, 2014 by yamini.v

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Ethanol boils at $78.4^{\circ}C$, the enthalpy of vaporization of ethanol is $42.4\: kJ/mol$. Calculate entropy of vaporization of ethanol.

asked Mar 13, 2014 by thanvigandhi_1

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What is the bond dissociation energy of $ HCl?( \Delta H_f^o\: of\: HCl(g), H(g), Cl(g) \: are\: -92.2, 217.7\: and\: 121\: kJ/mol$ respectively)

asked Mar 13, 2014 by thanvigandhi_1

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Calculate the standard enthalpy change for a reaction: \[\] $CO_2\: (g) + H_2\: (g) \rightarrow CO\: (g) + H_2O\: (g)$ given that $ \Delta H_f^o\: for\: CO_2\: (g), CO\: (g)\: and \: H_2O\: (g)\: as\: -393.5, -110.5\: and\: -241.8 \: kJ/mol$ respectively.

asked Mar 13, 2014 by thanvigandhi_1

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For a gaseous reaction $2A_2(g) + 5B_2(g) \rightarrow 2A_2B_5(g)$ at $ 27^{\circ}C$ the heat change at constant pressure is found to be $-50160\: J$. Calculate the value of internal energy change $(\Delta U). (R = 8.314 \: J/K\: mol)$

asked Mar 13, 2014 by thanvigandhi_1

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An ideal gas is taken through a process . The ratio of heat absorbed during AB to the work done on the gas during BC is ---

asked Mar 13, 2014 by yamini.v

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The heat of combustion of naphthalene $(C_{10}H_8(s))$ at constant volume was measured to be $-5133\: kJ/ mol$ at $298\: K$. Calculate the value of enthalpy change $(R = 8.314 \: J/Kmol)$

asked Mar 13, 2014 by thanvigandhi_1

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When helium gas is heated at constant pressure fraction of heat that goes into increasing the internal energy is ---

asked Mar 13, 2014 by yamini.v

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Assuming ideal behavior, calculate the work done when $1.6$ mole of water evaporates at $373 \: K$ against the atmospheric pressure of $1\: atm.$

asked Mar 13, 2014 by thanvigandhi_1

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A cyclic process is graphed as shown - Heat supplied in one cycle -

asked Mar 13, 2014 by yamini.v

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The freezing point & boiling point of water are marked as $\;-20^{0}C\;$ & $\;180^{0}\;$ respectively . The thermometer will read human body temperature $\;(37^{0}C)\;$ as -

asked Mar 13, 2014 by yamini.v

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Heat is supplied to a mono atomic gas at constant pressure . The ratio of $\;\bigtriangleup u : \bigtriangleup W : \bigtriangleup Q\;$ is -

asked Mar 13, 2014 by yamini.v

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The relationship between $\;T_{3} \; , T_{2} \; , T_{1} \;$ is -

asked Mar 13, 2014 by yamini.v

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Light from a source has its maximum intensity near the wavelength 500 nm . Assuming the body to be a black body calculate the temperature at its surface ?

asked Mar 13, 2014 by yamini.v

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A rod of radius ' r ' & length ' l ' is beaten such that its length doubles . If it took $\;t_{0}\;$ seconds to transfer heat Q , how much time will it take now ?

asked Mar 13, 2014 by yamini.v

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Two rods of equal cross - section have their ratio of lengths 1 : 2 . If the ratio of their coefficient of thermal conductivity are in the ratio 3 : 4 , the ratio of time taken for heat transfer for same temperature differance is -

asked Mar 13, 2014 by yamini.v

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A $5\; kg$ object is heated by a $50\; W$ power source . If the specific heat capacity of the object is $\;50 Jkg^{-1}K^{-1}\;$ , after what time will the temperature rise by $\;50^{0}C\;.$

asked Mar 13, 2014 by yamini.v

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An arbitrary shaped object is rotated about any axis of rotation $\;'w_{0} '$ . If the temperature is increased , then the new value of angular speed $\;w^{'}\;$ depends upon -

asked Mar 13, 2014 by yamini.v

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A square lamina is rotating about any axis perpendicular to its plane . The temperature is increased by $\;\bigtriangleup t\;$ , its moment of inertia $\;(I_{0})\;$ will increase by - (side of square lamina =a )

asked Mar 13, 2014 by yamini.v

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A rod (length = l) is rotating about it s center with a speed 'w' at temperature to . If the temperature is increased to $\;t_{0}+\bigtriangleup t\;$ , the new speed of rotation is -

asked Mar 13, 2014 by yamini.v

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Earth receives solar power at a rate of $\;8.2 Jcm^{-2}min^{-1}\;$ . Assuming that sun behaves like blackbody & the angle it substends on earth is $\;0.50^{0}\;$ , calculate its surface temperature - $\;(T=6 \times 10^{-8} W m^{-2}K^{-4})$

asked Mar 13, 2014 by yamini.v

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A blackbody of surface area $\;100 cm^{2}\;$ is placed inside an enclosure . The enclosure has a constant temperature at $\;127^{0}C\;$ & the blackbody is maintained at $\;227^{0}C\;$ by heating it electrically . If $\;\sigma=6 \times 10^{-8} Wm^{-2}K^{-4}\;$ , electric power needed to maintain the temperature

asked Mar 13, 2014 by yamini.v

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The rods AB,BC & CA made of same material & have equal cross - section . So , the temperature at C = ?

asked Mar 13, 2014 by yamini.v

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During a process , p & V to be related by the equation - $\;p=\large\frac{p_{0}}{1+(\large\frac{V_{0}}{V})^2}\;$ , $\;p_{0}\;$ & $\;V_{0}\;$ are constants . Change in temperature of the gas . When volume is changed from $\;V=V_{0}\;$ to $\;V=5V_{0}$

asked Mar 13, 2014 by yamini.v

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60 gm of ice at $\;-5^{0}C\;$ is mixed with 100 gm of water at $\;50^{0}C\;$. Latent heat of fusion = 80 cal/g , Specific heat of water = $\;1 cal/g^{0}C\;$ ,Specific heat of ice = $\;0.5 cal/g^{0}C$ . Then the mass of ice left in the mixture = ?

asked Mar 12, 2014 by yamini.v

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100 g of ice at $\;0^{0}C\;$ is mixed with 100 g of water at $\;20^{0}C\;$ . Latent heat of fusion of fusion is 80 cal/g & specific heat of water is $\;1 cal /g^{0}C\;$ . The final temperature of mixture =

asked Mar 12, 2014 by yamini.v

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Three conducting rods of same material & area of cross - section are figured as shown . Then , $\;\large\frac{l_{1}}{l_{2}}=?$

asked Mar 12, 2014 by yamini.v

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The figure expansion of an ideal gas through two processes A & B . Let $\;\bigtriangleup Q_{A}\;$ & $\;\bigtriangleup Q_{B}\;$ be the heat given to the system in processes A & B respectively . Then

asked Mar 12, 2014 by yamini.v

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The first law of thermodynamics following from

asked Mar 12, 2014 by yamini.v

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