O.5 Flashcards
Entropy changes
What is the definition of entropy?
Entropy is the measure of disorder in a system. It measures how many ways particles and their associated energy can be distributed.
What can entropy tell us about a chemical reaction?
Whether a change is feasible or not, or whether it can happen spontaneously.
What are three processes that tend to happen spontaneously?
- Liquid evaporating
- Solids dissolving
- Gases mixing
What is a factor that drives chemical processes?
A tendency towards randomizing or disordering.
Reactions that involve which energy change tend to be spontaneous most times?
Exothermic.
When can a endothermic reaction happen simultaneously?
When it involves randomizing or disordering of reactants.
What symbol represents entropy?
S
Rank the four physical states (s) (l) (aq) (g) in order of highest entropy to lowest entropy.
(g), (aq), (l), (s).
What is commonly associated with high entropy?
Gas, high temperature, complex molecules.
What is commonly associated with low entropy?
Solid, giant covalent molecules, ionic lattice.
What value does the entropy of a substance always have?
Positive.
Why is high temperature associated with high entropy?
Because entropy is a measure of the distribution of energy in a system. The greater the energy within a system, the higher the entropy, because particles will collide and exchange energy.
What is the symbol representation of entropy change in a reaction?
∆S
When is ∆S positive?
When products are more disordered than reactants.
When is ∆S negative?
When products are less disordered than reactants.
