Thermo chemistry Flashcards
(27 cards)
Kinetic energy
energy of motion of an object
Thermal Energy
Kinetic energy of molecules
Potential Energy
Stored energy due to position of composition
Units of energy
Joules (work or energy)
Calories (1cal is 4.184 kj)
Nutritional Calorie
1 calorie =
1000cal = 1 Kcal
Open system
can exchange matter and energy with the surroundings
Closed system
Can only exchange energy with the surroundings
Isolated system
Neither energy or matter are exchanged with the surroundings
Heat (q) is
Energy transferred from hot to cold until equilibrium is reached
Work (w)
Move an object or squash gas by applying force
Work is defined as
w=force X distance
First law of thermodynamics
energy is neither created or destroyed
And energy lost by a system is gained by the surroundings
Internal energy is
Sum of the kinetic/potential energy of all the parts of the system USE (U)
Determining the change in internal energy by
DELTA (U) = U final- U initial
What is a exothermic rxn
Heat is released during the reaction
What is a endothermic RXN
Heat is absorbed during the reaction.
Define state function
value depends only on the present state of the system and the conditions and does not depend on how that stat was achieved
Hess’s law
The enthalpy change of an overall process is the sum of the enthalpy changes of it individual steps
Heat capacity
Amount of heat required to raise the temperature of a object by 1 Kelvin
Specific heat
defined for 1 gram of a substance to be raised by 1 kelvin .
Difference between system and surroundings
System is part of the universe that we are studying
The surroundings is everything outside of our system
What is part of a state function
Temperature, internal energy, entropy
what is the 2nd law of thermodynamics
Entropy increases in a spontaneous process
What is the 3rd law of thermodynamics
Entropy is zero is a perfect crystal at 0 K
