In the reaction, C + O2 → CO2; ΔH = - 94 kcal. What is the heat content (enthalpy) of O2?
-94 kcal
> -94 kcal
< - 94 kcal
Zero
Correct Answer :
D. Zero
Related Questions
The gas law (PV = RT) is true for an __________ change.
Isothermal
Adiabatic
Both (A) & (B)
Neither (A) nor (B)
The main feature of Carnot refrigeration cycle is that, it
Does not need the addition of external work for its functioning
Transfers heat from high temperature to low temperature
Accomplishes the reverse effect of the heat engine
None of these
Pick out the wrong statement.
The conversion for a gas phase reaction increases with decrease in pressure, if there is an increase in volume accompanying the reaction
With increase in temperature, the equilibrium constant increases for an exothermic reaction
The equilibrium constant of a reaction depends upon temperature only
The conversion for a gas phase reaction increases with increase in pressure, if there is a decrease in volume accompanying the reaction
Pick out the wrong statement.
The values of (∂P/∂V)T and (∂2P/∂V2)T are zero for a real gas at its critical point
Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process
Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures
During a reversible adiabatic process, the entropy of a substance remains constant
Air-refrigeration cycle
Is the most efficient of all refrigeration cycles
Has very low efficiency
Requires relatively large quantities of air to achieve a significant amount of refrigeration
Both (B) and (C)
Absolute zero temperature signifies the
Minimum temperature attainable
Temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in
Temperature of the heat reservoir to which a Carnot engine rejects no heat
None of these
When a gas is subjected to adiabatic expansion, it gets cooled due to
Decrease in velocity
Decrease in temperature
Decrease in kinetic energy
Energy spent in doing work
Free energy changes for two reaction mechanism 'X' and 'Y are respectively - 15 and - 5 units. It implies that X is
Slower than Y
Faster than Y
Three times slower than Y
Three times faster than Y
In an irreversible process
Tds = dE - dW = 0
dE - dW - Tds = 0
Tds - dE + dW < 0
Tds - dT + dW < 0
__________ law of thermodynamics ascertains the direction of a particular spontaneous process.
Zeroth
First
Second
Third
Refrigerants commonly used for domestic refrigerators are
Ethyl chloride or methyl chloride
Freon-12
Propane
NH3 or CO2
With increase in temperature, the atomic heat capacities of all solid elements
Increases
Decreases
Remains unchanged
Decreases linearly
Joule-Thomson co-efficient which is defined as, η = (∂T/∂P)H = 1/Cp (∂H/∂T)P, changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is
0
∞
+ve
-ve
An ideal liquid refrigerant should
Not have a sub-atmospheric vapour pressure at the temperature in the refrigerator coils
Not have unduly high vapour pressure at the condenser temperature
Both (A) and (B)
Have low specific heat
Third law of thermodynamics is helpful in
Prediction of the extent of a chemical reaction
Calculating absolute entropies of substances at different temperature
Evaluating entropy changes of chemical reaction
Both (B) and (C)
A cyclic engine exchanges heat with two reservoirs maintained at 100 and 300°C respectively. The maximum work (in J) that can be obtained from 1000 J of heat extracted from the hot reservoir is
349
651
667
1000
Trouton's ratio is given by (where λb, = molal heat of vaporisation of a substance at its normal boiling point, kcal/kmol Tb = normal boiling point, °K)
λb/Tb
Tb/λb
√(λb/Tb)
√(Tb/λb)
Refrigeration cycle
Violates second law of thermodynamics
Involves transfer of heat from low temperature to high temperature
Both (A) and (B)
Neither (A) nor (B)
Those solutions in which there is no volume change upon mixing the components in the liquid state and which, when diluted do not undergo any heat change (i.e. heat of dilution is zero), are called __________ solutions.
Ideal
Real
Isotonic
None of these
If atmospheric temperature and dew point are nearly equal, then the relative humidity is
Zero
50%
Almost 100%
unpredictable
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
Zero
Positive
Negative
None of these
If we increase the pressure on a substance (which is at its triple point), then the triple point
Increases
Decreases
Remains unchanged
May increase or decrease; depends on the substance
Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will
Increase
Decrease
Remain unchanged
First fall and then rise
The internal energy of an ideal gas is a function of its __________ only.
Molecular size
Volume
Pressure
Temperature
The equation relating E, P, V and T which is true for all substances under all conditions is given by (∂E/∂V)T = T(∂P/∂T)H - P. This equation is called the
Maxwell's equation
Thermodynamic equation of state
Equation of state
Redlich-Kwong equation of state
PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process.
Isothermal
Isentropic
Isobaric
Adiabatic
The unit of fugacity is the same as that of the
Pressure
Temperature
Volume
Molar concentration
The ratio of equilibrium constants (Kp2/Kp1) at two different temperatures is given by
(R/ΔH) (1/T1 - 1/T2)
(ΔH/R) (1/T1 - 1/T2)
(ΔH/R) (1/T2 - 1/T1)
(1/R) (1/T1 - 1/T2)
At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is
Zero
One
Infinity
Negative
The unit of equilibrium constant of a chemical reaction is the same as that of
Molar concentration
Temperature
Internal energy
None of these