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Heat produced in calories by the combustion of one gram of carbon is called:
It is the definition of calorific value.
The temperature of the system decreases in an:
For the isothermal expansion of an ideal gas:
In an isochoric process, the increased internal energy is:
In an isochoric process, ΔV=0.
Hence, work done PΔV = W = 0.
So, ΔE = q+0.
Hence, the increase in internal energy will be equal to heat absorbed by the system.
Internal energy is an example of:
Internal energy, enthalpy, and entropy are state quantities because they describe quantitatively an equilibrium state of a thermodynamic system, irrespective of how the system arrived in that state.
The process in which no heat enters or leaves the system is termed as:
An adiabatic process occurs without transfer of heat or mass of substances between a thermodynamic system and its surroundings. In an adiabatic process, energy is transferred to the surroundings only as work.
If in a container neither mass and nor heat exchange occurs then it constitutes a ______.
An isolated system neither shows exchange of heat nor matter with surroundings.
Which of the following is true for an adiabatic process:
A process that does not involve the transfer of heat or matter into or out of a system, so that ΔQ = 0, is called an adiabatic process and such a system is said to be adiabatically isolated.
Among the following, intensive property is:
An intensive property is a property of matter that does not change as the amount of matter changes. It is a bulk property, which means it is a physical property that is not dependent on the size or mass of a sample. In contrast, an extensive property is one that does depend on sample size.
For the reaction of one mole of zinc dust with one mole of sulphuric acid in a bomb calorimeter, ΔU and W correspond to:
Bomb calorimeter is commonly used to find the heat of combustion of organic substances which consists of a sealed combustion chamber, called a bomb. If a process is run in a sealed container then no expansion or compression is allowed, so w = 0 and ∆U = q.
∆U < 0, w = 0
Which of the following expressions represent the first law of thermodynamics:
At 270C one mole of an ideal gas is compressed isothermally and reversibly from a pressure of 2 atm to 10 atm. The value of ΔE and q are (R = 2):
Isothermally (at constant temperature) and reversible work.
w = -2.303nrt log(P1/P2)
at constant temperature , ΔE = 0
ΔE = Q + W,
Q = −W = −965.84 cal
The heat required to raise the temperature of a body by 1K is called:
The heat required to raise the temperature of a body by 1 K is called thermal capacity. In other words, when q is the heat supplied to the body and the temperature rises by 1 K, then the thermal capacity of body is q.
Which of the following is true for the reaction H2O(l) ⇋ H2O(g) at 1000C at one atmosphere:
H2O(l) ⇋ H2O(g)
As we know that, at equilibrium, ΔG=0
Identify the correct statement regarding entropy:
According to the third law of thermodynamics (regarding the properties of systems in equilibrium at absolute zero temperature):
The entropy of a perfect crystal at absolute zero is exactly equal to zero. At absolute zero (zero kelvin), the system must be in a state with the minimum possible energy, and the above statement of the third law holds true provided that the perfect crystal has only one minimum energy state.
Maximum entropy will be in which of the following:
Entropy of gases is highest.
If enthalpies of formation C2H4 (g), CO2 (g) and H2O (l) at 250C and 1 atm. pressure be 52, –394 and –286 KJ mol–1 respectively. The enthalpy of combustion of C2H4 (g) will be:
The iombustion of C2H4 can be derived as follows :
Heat of neutralization of strong acid and weak base is:
The heat evolved in the combustion of methane is given by the following equations:
CH4 (g) + 2O2 (g) → CO2 (g) + H2O (l) ΔH = -890.3 KJ
How many grams of methane would be required to produce 444.15 KJ of heat of combustion:
CH4 required = (445.15 x 16) / 890.3 = 8gm
One gram sample of NH4NO3 is decomposed in a bomb calorimeter. The temperature of the calorimeter increases by 6.12 K. The heat capacity of the system is 1.23 kJ/g/deg. What is the molar heat of decomposition for NH4NO3?
Heat of decomposition, ΔE = m.s.ΔT
= 1 x 1.23 x 6.12 = 7.5276 kJ
Molar heat of decomposition for NH4NO3 = 7.5276 x 80 = 602.2 kJ/mol