ThermodynamicConcepts&Equations Flashcards
the equation for Celcius to Kelvin
Celcius plus 273.15
What is 0 degrees celsius in Kelvin
273.15K
What is 32 degrees Fahrenheit in Kelvin
273.15K
What is 32 degrees Fahrenheit in Celcius
0 C
equation from Fahrenheit to Celsius
C= 5/9(F-32)
Equation from Celsius to Fahrenheit
F=9/5C + 32
Is thermal energy kinetic or potential
Kinetic. Molecules are moving around which changes the amount of energy in a system
is gravitational energy potential or kinetic
Potential
Is mechanical energy potential or kinetic
BOTH
How is temperature measured?
in Celcius, Fahrenheit, and usually Kelvin
What is temperature?
A measure of the AVERAGE kinetic energy within a medium/system.
an arbitrary measure of the amount of energy within a solid, liquid, or gas
What is thermal energy?
A measure of the TOTAL amount of energy that exists in a system. A measure of TOTAL kinetic energy of the particles in a moving system.
How is thermal energy measured?
Joules (J) = kg x m^2/s^2
How is heat measured
joules
What is the symbol for heat, a form of thermal energy
q
What is heat
the flow of thermal energy. Thermal energy being transferred from a hot object to a colder one.
What is Internal Energy (U)
the amount of CHEMICAL energy that is stored in a substance.
The SUM of:
stored chemical energy in atoms (both PE and KE), stored chemical energy in molecules(chemical bonds), and stored chemical energy between molecules (intermolecular)
Internal Energy is also known as
“heat content”
Main concept of The Zeroth Law of Thermodynamics
Equiliburum
Main concept of The First Law of Thermodynamics
Conservation
Main concept of The Second Law of Thermodynamics
Entropy (disorder)
Main concept of The Third Law of Thermodynamics
residual entropy, derived from second law
The Zero Law states what about heat flow
At thermal equilibrium, there is NO net heat flow.
Would hot or cold air have more kinetic energy? why?
Hot. Particles moving around faster
Would hot or cold air have more entropy? Why?
Hot. More movement of particles means more chaos.
Would hot or cold air have less entropy? Why?
Cold. slower moving particles, more organized means less entropy.
What gas equation can be derived from the understanding the zeroth law of thermodynamics?
p1v1/n1 = p2v2/n2
Because when T is constant, PV=nRT can become PV/n = RT
Describe the first law of thermodynamics
Total energy in an isolated system is CONSTANT even when the system is changed from one phase to another.
100J in a system will always be 100J. But the ratio can change. you have 60J heat and 40J work, or 50/50. It will always be 100 for that system.
Also, if average kinetic energy goes up (temperature), then total KE will also go up (thermal energy)
What is the relationship between
C (specific heat) and DeltaT (change in Tf-Ti) in the equation q=mC(deltaT)
Specific heat and delta T are inversely related. A substance with a Higher Specific Heat will have a smaller change in temperature.
A substance with a lower specific heat will have a larger temperature change.
What is the equation for: change in internal energy of a system
DeltaU = Q +/- W
Q is greater than 0 when?
Energy flows into the system. Endothermic process.
An endothermic process has energy that flows?
Into the system (+)
Q is less than 0 when?
Energy flows out of the system and into the surrounds. Exothermic Process
An exothermic process has energy that?
Flows out of the system (-)
W is greater than zero (+) when? Give an example.
Work is done by the system to the surroundings. Such as gas expansion.
W is less than zero (-) when? Give an example
Work is done on the system by the surroundings, such as compression of a gas with the piston. (diaphgram contraction?)
When heat is being added to the system, Q is positive or negative?
Positive - endothermic
When heat is leaving the system and escaping to the surroundings, Q is positive or negative?
Negative - exothermic
Bing
Bong
If deltaU is negative, what does that mean regarding the system’s temperature?
Temperature is decreasing
