Thermo Concepts Ref: Indiabix, ARC Flashcards
Which law is the basis for the manufacture of thermometers?
Zeroth Law of Thermodynamics
How many degrees of freedom has each of the following systems?
14. Liquid water in equilibrium with its vapor
one
Liquid water in equilibrium with a mixture of water vapor and nitrogen.
two
A liquid solution of alcohol in water in equilibrium with its vapor.
two
Energy is added to the water as work but is extracted from the water
as heat was performed by
joule
These properties depend on the current state of the system and not
on how the system reaches that state.
state functions
Which of the following statement is correct?
a. The standard heat of formation of an element is negative.
b. Since △H = △U + △PV and can never be equal to △U.
c. Q and W are state functions.
d. Q + W is a state function.
Q + W is a state function.
The amount of heat absorbed when CO2 gas reacts with a solid CaO
to form solid CaCO3 is measured in a bomb calorimeter at constant
volume. The data obtained give a direct measure of
△U
For a constant pressure reversible process, the enthalpy (∆H)
change of the system is
. ∫CpdT
Cv is given by
(∂U/ ∂T)v
Equation which relates pressure, volume, and temperature of a
gas is called
Equation of state
The equation, PV = nRT is best obeyed by gases at
low pressure and high temperature
Compressibility factor of a gas is
unity, if it follows PV = nRT
Cp – Cv = R is valid for
ideal gases
For monoatomic gases, Cp / Cv equals
1.67
Isobaric process means a constant
pressure process
For an isothermal process the internal energy of a gas
remains unchanged
In an adiabatic process
heat transfer is zero
From PVn = C, when n = 0, the process is
isobaric
From PVn = C, the process is isochoric if n equals
∞
A solid is transformed into vapor without going through the liquid
phase at
a. below triple point c. triple point
Determine whether water is compressed liquid, superheated
vapor, saturated liquid, saturated vapor, or a mixture of saturated
liquid and saturated vapor, in each case. If the state is determined
to be a mixture, determine the quality.
(i) At 10 MPa and an entropy of 3.3 kJ/kg-K
(ii) At 320 0C and 5.6 MPa
(iii) With specific volume of 0.10 m3
/kg at 1 MPa
a. subcooled, superheated, mixture (0.50)
b. mixture (0.40), superheated, subcooled
c. superheated, mixture (0.60), subcooled
d. subcooled, mixture (0.30), superheated
subcooled, superheated, mixture (0.50)
Work output of turbine is __ the work input to the pump
greater than
The efficiency of Carnot cycle is ___ the efficiency of Rankine
greater than
The losses in condenser are
small
Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.
ISOTHERMAL
Internal energy change of a system over one complete cycle in a cyclic process is
Zero
Heating of water under atmospheric pressure is an __________ process.
Isobaric
Van Laar equation deals with the activity co-efficients in
binary solutions
High __________ is an undesirable property for a good refrigerant.
Viscosity
Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favoured by the
low pressure and low temperature
Entropy is a measure of the __________ of a system.
Disorder
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
Negative
Fundamental principle of refrigeration is based on the __________ law of thermodynamics.
Second
A refrigeration cycle is a reversed heat engine. Which of the following has the maximum value of the co-efficient of performance (COP) for a given refrigeration effect ?
Carnot refrigeration cycle
A refrigerator may be termed as a
Heat pump
Entropy of an ideal gas depends upon its
Pressure and temperature
Isobaric process means a constant process.
Pressure
No work is done by the system, when a reaction occurs at constant
Volume
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
Clayperon-Claussius equation
Equilibrium constant decreases as the temperature
increases, for an exothermic reaction.
Compressibility factor for almost all the gases are approximately same at the same
reduced pressure and reduced temperature.
Free energy change at equilibrium is
Zero
The temperature at which both liquid and gas phases are identical, is called the __________ point
Critical
Any substance above its critical temperature exists as
Gas
Isentropic process means a constant __________ process.
Entropy
In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when
n=1
A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.
Subcooled
At absolute zero temperature, all substances have the same
heat capacity
Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
1160 - using PVN/rt
N=58
V= 448 L ~ 0.448 m3
r= 8.314
K= 273.15
P= 101325
