Thermodynamics

  • exothermic reaction = a reaction which releases energy, usually as heat, from a system to its surroundings

  • endothermic reaction = a reaction which absorbs energy from its surroundings, usually in the form of heat

  • spontaneous processes = processes that can actually happen

    • Tend to be exothermic

  • non-spontaneous processes = processes that can never happen regardless of circumstance

  • exergonic reaction = a spontaneous chemical reaction in which there is a net release of free energy

    • Catabolic

  • endergonic reaction = a non-spontaneous chemical reaction in which free energy is absorbed from the surroundings

    • Anabolic

  • Generally, a forward reaction is spontaneous, but its reverse is non-spontaneous

Laws

The Zeroth Law

If two bodies are each in thermal equilibrium with a 3rd body, they must also be in equilibrium with each other. This law allows scientists to introduce a thermometer into a system and allow that to be the 3rd body, then defining a temperature scale for each of the 2 other bodies.

  • thermal equilibrium = the state where two or more objects in thermal contact reach the same temperature, resulting in no net transfer of thermal energy between them

The First Law

Energy can be transferred and transformed but not created or destroyed.

  • Also called the law of conservation of energy

  • Follows the exact same principle as the law of conservation of mass

The Second Law

Every energy transfer that takes place will increase the entropy of the universe and reduce the amount of usable energy available to do work.

  • Sometimes, in rare cases, the overall entropy of the universe will be unchanged rather than increased

  • All closed systems are attempting to reach equilibrium at which they can no longer increase the universe’s entropy

    • Entropy is at a maximum in equilibrium

    • No useful work can be done in equilibrium

The Third Law

When the entropy of each and every element (in their perfectly crystalline states) is taken as 0 at absolute 0 temperature, the entropy of every substance must have a positive, finite value.

  • It is impossible to achieve absolute 0

    • An infinite number of steps would have to be performed in order to reach absolute 0

  • This law is based off of perfect crystals, which have an entropy of 0 at absolute 0

Enthalpy

  • enthalpy = a measurement of a system's internal energy

Entropy

  • entropy = a measurement of disorder

Gibbs Free Energy

A way to determine whether a reaction will occur on its own.

  • Also referred to as available energy

ΔG=ΔH−TΔS\Delta G=\Delta H-T\Delta S

change in available energy = change in enthalpy − system temperature * change in entropy

  • If, \Delta G<0 ’s a spontaneous reaction

    • These can be called exergonic reactions

    • This reaction can occur on its own without any interference

  • If, \Delta G>0 ’s a non-spontaneous reaction

    • These can be called endergonic reactions

    • This reaction will need interference in order to start and continue

  • If, ΔG=0\Delta G=0 it’s an equilibrium reaction

    • No work can be done in living organisms

  • System temperature is measured in Kelvin

  • ΔH\Delta H will sometimes be referred to as a system’s total energy

Colors

#b6c289

#e79796

  • #FFB284

    • #f7cb98

#88ae53 for other stuff