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Indiabix, etc. - ChELE M2024 > Heat Transfer / Thermo > Flashcards

Heat Transfer / Thermo Flashcards

1
Q

another term for momentum diffusivity

A

kinematic viscosity, m^2/s

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2
Q

heat transfer through physical contact

A

conduction

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3
Q

heat transfer due to movement of fluid (gas/ liquid)

A

convection

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4
Q

heat transfer due to electromagnetic waves

A

radiation

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5
Q

Under the same temperature gradient across various metal plates of the same thickness, the heat conducted per unit of surface area will be largest across

A

copper

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6
Q

If a man touches two metals which are kept together at room temperature, why would one metal feel colder than the other?

A

One has a high thermal conductivity

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7
Q

The insulation ability of an insulator with the presence of water would

A

Decrease

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8
Q

is the change in temperature of a gas when it undergoes isenthalpic expansion.

A

Joule Thomson Effect

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9
Q

__________ explains the equilibrium constant for any chemical reaction.

A

Law of mass action

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10
Q

If the vapour pressure at two
temperatures of a solid phase in equilibrium with its liquid phase are known, then the latent heat of fusion can be calculated by the

A

Clayperon-Claussius equation

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11
Q

Temperature scales with ratios that depend on ratios of heat transfer between a reversible heat engine and the reservoirs.

A

Absolute temperature scales

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12
Q

Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure.

A

-fugacity
-partial pressure
-activity co-efficient

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13
Q

“The rate at which a substance reacts is proportional to its active mass and the rate of a chemical reaction is proportional to the product of active masses of the reacting substances”. This is the

A

Law of Mass Action
(none of these and sagot)

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14
Q

The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.

A

Gibbs free energy

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15
Q

A nozzle is a device, which

A

increases kinetic energy and decreases pressure.

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16
Q

For any closed system formed from known amounts of prescribed chemical species, the equilibrium state is completely determined when any two independent variables are fixed.

A

Duhem’s theorem

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17
Q

Lee/Kesler correlation is only applicable for the following compound

A

non-polar and slightly polar

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18
Q

It is a liquid that does not flow at all until a threshold shear stress is attained.

A

Bingham plastic

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19
Q

The work done in a free expansion process is

A

Zero

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20
Q

Reaction conversion increases with an increase in temperature in the

A

Reversible endothermic

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21
Q

Potential flow is the flow of

A

Incompressible fluids with no shear

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22
Q

With increase in molecular weight of the gas, the head developed by a centrifugal compressor will ___

A

decrease

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23
Q

Pressure drop is proportional to the 1st power of the velocity

A

Laminar flow

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24
Q

Closed system that produce the maximum work?

A

Reversible cyclic process

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25
How to calculate non reversible entropy?
Entropy is state function. S,rev = S,irrev
26
Gibbs Free Energy (Proponent, Equation, Definition)
Josiah Willard Gibbs G=H-TS Maximum work by system at P&T=k
27
miles to ft
1 mi = 5280 ft
28
If a heat transfer equipment, dirt or scale may be accounted by introducing resistance called ______
fouling factors
29
thermal conductivity of steel, ka
45W/m-K 26 BTU/hr-ft-F
30
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are A zero B one C two D three
zero
31
What is the value of ln y (where y = activity co-efficient) for ideal gases ? A Zero B Unity C Infinity D Negative
Zero
32
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
one
33
Any substance above its critical temperature exists as A saturated vapour B solid C gas D liquid
gas
34
Which of the following decreases with increase in pressure ? A Melting point of ice B Melting point of wax C Boiling point of liquids D none of these
Melting point of ice
35
(1) is the mathematical expression
co-efficient of thermal expansion.
36
In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when A n = y = 1.4 B n = 0 C n = 1 D n = 1.66
n = 1
37
A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid. A subcooled B saturated C non-solidifiable D none of these
subcooled
38
For a real gas, the chemical potential is given by A RT dlnP B RT dlnf C R dlnf D none of these
RT dlnf
39
At absolute zero temperature, all substances have the same A heat capacity B crystalline structure C entropy D none of these
heat capacity
40
Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in A increased COP. B same COP. C decreased COP. D increased or decreased COP ; depending upon the type of refrigerant.
increased COP.
41
Pick out the correct statement. A If an insoluble gas is passed through a volatile liquid placed in a perfectly insulated container, the temperature of the liquid will increase. B A process is irreversible as long as Δ S for the system is greater than zero. C The mechanical work done by a system is always equal to P.dV. D The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.
The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.
42
Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
A 580 B 640 C 1160 D data insufficient; can't be computed
43
The thermodynamic law, PVy = constant, is not applicable in case of A ideal compression of air. B free expansion of an ideal gas. C adiabatic expansion of steam in a turbine. D adiabatic compression of a perfect gas.
free expansion of an ideal gas.
44
Mollier diagram is a plot of
entropy vs. enthalpy
45
is the mathematical expression for
none of these
46
The activity of an ideal gas is numerically __________ its pressure.
equal to
47
Specific heat of a gas for a reversible adiabatic process is A negative B zero C infinity D none of these
zero
48
When a gas in a vessel expands, its internal energy decreases. The process involved is A reversible B irreversible C isothermal D adiabatic
reversible
49
A system is said to be isopiestic, if there is no __________ change.
pressure
50
In a turbine, the fluid expands almost A isothermally B isobarically C adiabatically D none of these
adiabatically
51
The unity of Planck's constant 'h' in the equation, E = hv is
J*S
52
Refrigeration capacity of a household refrigerator may be round about __________ tons. 0.15 1.5 4.5 6.5
0.15
53
54
An ideal gas is taken around the cycle ABCA as shown in P-V diagram below :The work done by the gas during the cycle is equal to A 12 P1V1 B 6 P1 V1 C 3 P1V1 D P1 V1
3 P1V1
55
In polytropic process (PVn = constant), if n = 1; it means a/an __________ process.
isothermal
56
The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.
increases
57
A solid metallic block weighing 5 kg has an initial temperature of 500°C. 40 kg of water initially at 25°C is contained in a perfectly insulated tank. The metallic block is brought into contact with water. Both of them come to equilibrium. Specific heat of block material is 0.4 kJ.kg^-1. K^-1. Ignoring the effect of expansion and contraction and also the heat capacity to tank, the total entropy change in kJ.kg^-1 , K^-1 is
0
58
dW and dq are not the exact differential, because q and W are A state functions B path functions C intensive properties D extensive properties
path functions
59
Activity co-efficient is a measure of the A departure from ideal solution behaviour. B departure of gas phase from idea] gas law. C vapour pressure of liquid. D none of these.
departure from ideal solution behaviour.
60
61
While dissolving a gas into a liquid at a constant temperature, the ratio of the concentration of the gas in the solution phase and in the gaseous phase is
constant
62
For an isothermal reversible compression of an ideal gas A only ΔE = 0 B only ΔH =0 C ΔE = ΔH = 0 D dQ = dE
ΔE = ΔH = 0
63
Melting of ice exemplifies a/an A adiabatic process. B endothermic reaction. C exothermic reaction. D process involving a chemical reaction.
endothermic reaction.
64
Kopp's rule is used to calculate the heat capacity of
solids
65
__________ explains the equilibrium constant for any chemical reaction.
Law of Mass Action
66
Pick out the wrong statement. A A closed system does not permit exchange of mass with its surroundings but may permit exchange of energy. B An open system permits exchange of both mass and energy with its surroundings. C The term microstate is used to characterise an individual, whereas macro-state is used to designate a group of micro-states with common characteristics. D none of the above.
none of the above.
67
Requisites of a reversible process is that the A system and surroundings pressure be equal. B friction in the system should be absent. C system and surroundings temperature be equal. D none of these.
B friction in the system should be absent.
68
The energy of activation of exothermic reaction is A zero. B negative. C very large compared to that for en-dothermic reaction. D not possible to predict.
D not possible to predict.
69
Pick out the wrong statement. A The chemical potential of a pure substance depends upon the temperature and pressure. B The chemical potential of a component in a system is directly proportional to the escaping tendency of that component. C The chemical potential of ith species (μi) in an ideal gas mixture approaches zero as the pressure or mole fraction (xi) tends to be zero at constant temperature. D The chemical potential of species 'i' in the mixture (μi) is mathematically represented as, (1) , where, n, ni and nj respectively denote the total number of moles, moles of ith species and all mole numbers except ith species. 'G' is Gibbs molar free energy.
C The chemical potential of ith species (μi) in an ideal gas mixture approaches zero as the pressure or mole fraction (xi) tends to be zero at constant temperature.
70
In the reaction; N2 + O2 (1) 2NO, increasing the pressure will result in A shifting the equilibrium towards right, B shifting the equilibrium towards left. C no change in equilibrium condition. D none of these.
no change in equilibrium condition.
71
Joule-Thomson effect i.e., a throttling process is a constant __________ process. A entropy B temperature C internal energy D enthalpy
D enthalpy
72
The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is A 3 B 1 C 2 D 0

Indiabix, etc. - ChELE M2024 (7 decks)

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