Concepts Of Thermodynamics Flashcards
What are the two forms of energy?
Potential energy
Kinetic energy
What is potential energy?
Any form of stored energy
What is kinetic energy?
Energy of moving objects
What are examples of potential energy?
Gravitational
Elastic
Chemical
Electrical
What are examples of kinetic energy?
Radiant
Thermal
Sound
Mechanical
What are the three types of systems?
Open
Closed
Isolated
What happens in an open system?
Mass transfer
Heat transfer
What happens in a closed system?
No mass transfer
Heat transfer
What happens in an isolated system?
No mass transfer
No heat transfer
What is the Zeroth Law of Thermodynamics?
If two systems are in thermal equilibrium with a third system, the two original systems are in thermal equilibrium with each other.
What is the first Law of Thermodynamics?
Energy cannot be created or destroyed, it can only be transferred from one form to another.
What is the Law of Conservation of Energy?
The change in internal energy of a closed system will be equal to the heat added or released by the system on its surrounding or work done on the system by its surroundings.
What does each figure mean in this equation?
🔺U=Q+W
🔺U= change in internal energy
Q= heat added to the system
W = work done by the system (mass transfer)
If Q is positive what does this mean?
Heat has been added to the system.
Endothermic process
If Q is negative what does this mean?
Heat released from the system.
Exothermic process
What does isovolumetric mean?
Constant volume
🔺U=Q
No work is done on it by the system
What does isothermal mean?
Constant temperature.
Q=W
No change in internal energy
What does adiabatic mean?
🔺U= W
Internal energy changes only for work done or received by the system
What does one calorie do?
The heat needed to raise the temperature of one gram of water one degree under standard pressure.
What is one calorie in joules?
4.184J
What is heat capacity (C)?
Amount of heat required to raise a substance temperature by 1 kelvin
What is specific heat capacity (Cs) ?
Amount of heat required to raise one gram of a substance by 1 kelvin
What is enthalpy?
Measurement if energy in a thermodynamic system (joules)
What is the equation for enthalpy?
🔺H=🔺U+🔺(PV)
P= pressure
V= volume
Why does 🔺H = Q in biological system?
Biological systems are under constant pressure and volume rarely changes.
🔺H=🔺U
🔺U=Q
Therefore 🔺H=Q
What is 🔺H in an endothermic process?
Positive
What is 🔺H in an exothermic process?
Negative
What is the second law of thermodynamics?
The universe is always moving towards maximum disorder.
What is entropy?
Measure of disorder
What are the symbols in this equation mean?
S= KB Ln W
KB= Boltzmann constant
Ln= natural logarithm
W= microstates
What is the third law of thermodynamics?
At absolute zero (0Kelvin) the entropy of a perfect crystalline substance is zero.
What is the equation for Gibbs free energy?
G=H-TS
What are the symbols in the Gibbs free energy equation?
G=Gibbs free energy
H=enthalpy
S=Entropy
T=temperature
What does the number for 🔺G indicate?
Negative= spontaneous in forward direction only
Zero= reaction at equilibrium
Positive= non-spontaneous
Why is T always positive in Gibbs free energy equation?
Temperature is in Kelvin
What is free energy of formation?
The free energy change which result from 1mol of substance prepared from its elements at standard pressure (1atm) and a given temperature (usually 298K)
What is the free energy formation of chemical elements?
0
What is oxidative metabolism?
A process by which nutrients from our diet are converted to energy.
What is thermochemistry?
The study of heat changes that occur during a chemical reaction.
What is the standard enthalpy change of a reaction?
The heat transferred by a chemical reaction under standard conditions
What is the standard enthalpy change of formation?
The enthalpy change when 1mol of a compound is formed under standard conditions for it’s constituent elements in their standard states
What is the bond dissociation enthalpy?
The enthalpy change, per mol, in the gas phase, when a bond is broken of compound A-B through the reaction: AB—> A+B
What is the standard entropy change of a reaction?
The difference in standard entropy between products and reactants of a system under standard conditions.