KA6- Reaction Feasibility Flashcards
What is the standard enthalpy of formation
definition
enthalpy change when one mole of a substance is formed from its elements in their standard states
What is the standard state of a substance?
Most stable state at a pressure of 1 atmosphere and at a specified temperature usually as 298K (25c)
What is entropy?
S
the entropy of a system is a measure of the degree of disorder of the system
If reaction has higher entropy the degree of disorder is?
Higher
In terms of entropy, how do s, l, g compare in order of lowest to highest entropy?
Solids-> liquids-> gases
If temperature increases entropy?
Increases
What happens to entropy at the melting point and boiling point of a substance?
a rapid increase at mp and even more at bp
What is the 2nd law of thermodynamics?
The total entropy of a reaction system and its surroundings always increases for a spontaneous process
What happens if heat energy released by the reation system into the surroundings?
Increases entropy
What happens if heat energy absorbed by the reaction system from the surroundings?
Decreases entropy
What is the 3rd law of thermodynamics?
The entropy of a perfect crystal at 0 K is 0.
What is the standard entropy of a substance?
entropy value for the substance in its standard state
How can the change in standard entropy for a reaction system be calculated?
from standard entropies fo reactions and products
What is the symbol for Gibb’s free energy?
🔺G
What is the deciding factor for working out if a reaction is feasible?
If free energy delta G is negative the reaction is feasible
