Unit 5 - Energy Flashcards
What is energy?
CAPACITY to do WORK or supply HEAT
What are the two fundamental forms of energy?
Potential and Kinetic
Example forms of energy
Mechanical, Thermal, Chemical, Electrical, and Nuclear
What type of energy is thermal?
Kinetic
What type of energy is chemical?
Potential
What is the internal energy of a system?
The sum of all kinetic and potential energies in every molecule or ion in the system.
How can a system exchange energy?
By transferring heat or by doing work
What is thermodynamic standard state?
Most stable form of a substance at 1 atm and specified temperature (typical 25 C); 1 M concentration for all substance in solution
What is standard enthalpy of reaction?
When enthalpy change is measured under standard conditions
Hess’s Law
The overall enthalpy change for a reaction is equal to the sum of the enthalpy changes for the individual steps in the reaction.
Standard Heat of Formation
The enthalpy change for the formation of 1 mol of a substance in its standard state from is consituent elements in their standard states.
What value is th standard heat of formation of an element?
Zero (including diatomic molecules eg H2)
spontaneous process
Once started, proceeds on its own without external influence.
Favored by a decrease in H and an increase in S
Entropy (S)
Amount of molecular randomness in a system. (Gasses > Solids)
Nonspontaneous process
Favoured by an increase in H and a decrease in S
