Thermodynamic Cycle Flashcards
What is the first law of thermodynamics?
Energy cannot be created or destroyed, only transformed.
True or False: The second law of thermodynamics states that entropy in a closed system can decrease over time.
False
Fill in the blank: The measure of the disorder or randomness in a system is known as ____.
entropy
What is the equation for the first law of thermodynamics?
ΔU = Q - W
In the context of thermodynamics, what does ‘Q’ represent?
Heat added to the system
What does ‘W’ represent in the first law of thermodynamics?
Work done by the system
True or False: An isothermal process occurs at constant temperature.
True
What is an adiabatic process?
A process in which no heat is exchanged with the surroundings.
What is the significance of absolute zero in thermodynamics?
It is the point where molecular motion stops, and entropy reaches its minimum value.
What is a Carnot cycle?
A theoretical cycle that provides the maximum possible efficiency for a heat engine.
Fill in the blank: The efficiency of a Carnot engine depends only on the temperatures of the ____ and ____ reservoirs.
hot, cold
What is the formula for the efficiency of a Carnot engine?
η = 1 - (T_c / T_h)
Define ‘enthalpy’.
The total heat content of a system, often represented as H = U + PV.
What is Gibbs free energy?
A thermodynamic potential that measures the maximum reversible work obtainable from a closed system at constant temperature and pressure.
True or False: A process is spontaneous if it decreases the Gibbs free energy.
True
What does the symbol ΔH represent?
Change in enthalpy
What is a state function?
A property of a system that depends only on its current state, not on how it reached that state.
Fill in the blank: The three laws of thermodynamics are the first law, the second law, and the ____ law.
zeroth
What does the zeroth law of thermodynamics state?
If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
What is the difference between an open and closed system?
An open system can exchange both energy and matter with its surroundings, while a closed system can exchange only energy.
What is the unit of heat in the SI system?
Joule (J)
Define ‘specific heat capacity’.
The amount of heat required to change the temperature of one unit mass of a substance by one degree Celsius.
What is the formula for calculating heat transfer?
Q = mcΔT
True or False: The heat capacity of a substance is dependent on the amount of substance present.
True
What is thermal conductivity?
The ability of a material to conduct heat.
Fill in the blank: In a phase transition, the temperature remains constant while the ____ is added or removed.
heat
What is the latent heat of fusion?
The amount of heat required to convert a unit mass of a solid into a liquid at constant temperature.
What does the term ‘heat engine’ refer to?
A device that converts thermal energy into mechanical work.
What is the purpose of a heat pump?
To transfer heat from a colder area to a warmer area.
Define ‘reversible process’ in thermodynamics.
A process that can be reversed without leaving any change in the system or surroundings.
What is the significance of the Clausius statement of the second law of thermodynamics?
It states that heat cannot spontaneously flow from a colder body to a hotter body.
Fill in the blank: The Carnot efficiency is a theoretical limit and cannot be achieved in ____ engines.
real
What is the role of a thermodynamic cycle?
To convert energy from one form to another in a systematic way.
What is the relationship between pressure, volume, and temperature in an ideal gas?
PV = nRT, where n is the number of moles and R is the ideal gas constant.
True or False: An ideal gas is one that perfectly follows the ideal gas law under all conditions.
False
What is Boyle’s Law?
At constant temperature, the pressure of a gas is inversely proportional to its volume.
What is Charles’s Law?
At constant pressure, the volume of a gas is directly proportional to its absolute temperature.
What is the significance of the Helmholtz free energy?
It measures the useful work obtainable from a system at constant volume and temperature.
Fill in the blank: The thermal efficiency of a heat engine is defined as the ratio of ____ to the heat input.
work output
What is the relationship between entropy and the direction of spontaneous processes?
Spontaneous processes increase the total entropy of a system and its surroundings.
