9. Entropia Energia livre e equilíbrio Flashcards
Processos Espontâneos?
Ocorrem naturalmente. A car rusts. Natural ocurrance.
An ice cube in a warm room becomes liquid water, naturally, no external force.
Non-Spontaneous Reactions?
Requires external force. Jack in the box, we need to crank it to produce a result. Combustion of some gases. Compression of springs is not spontaneous.
Requires an external force.
Exothermic reactions?
We release heat. Heat flows from hotter to colder. Everything tends to converge into a low energy stable state.
Releasing heat is releasing energy.
Likely spontaneous
Endothermic reactions?
Absorbing heat.
Likely to be non-spontaneous.
But and ice cube is spontaneous but absorbs heat
Entropy?
The universe tends to go from an ordered state into an unordered state.
There are more ways of being chaotic.
A way of measuring how energy is distributed within a system.
If entropy decreases?
Its likely to be non spontaneous.
unlikely for something to become more ordered.
The more ordered it is the less entropy it has
If entropy increases?
Its likely to be more spontaneous, because the universe tends to chaos, more than it tends to order, without any external forces.
First law of thermo?
Energy cannot be created or destroyed.
Second law of thermo?
Entropy is disorder.
The entropy of the universe is always increasing
Within a system there is a tendency to increase entropy.
Entropy is also how energy is dispersed
A liquid is less ordered than a solid is, so the liquid has higher entropy
There is less energy needed to order and unordered substance, for example there is more information needed, or energy to describe a solid and the interactions between its molecules, than there is to describe a liquid, in which the interactions are random.
3rd Law of Thermo?
A crystalline solid at absolute zero has an entropy of zero.
It is the most ordered state a substance can be in.
Gibbs free energy
Tells us whether a process is going to be spontaneous or not.
If deltaG is negative then the process is spontaneous.
