AP Chem- Thermodynamics terms

Calorimetry

Measurement of heat that’s exchanged or transferred in a chemical system

Critical Temperature

Highest Temperature at which a liquid phase can form

Dynamic Equilibrium

when evaporation and condensation occur at the same rate

Endothermic Reaction

Energy of the system increases so the energy must be taken up by absorption from the surroundings

Energy

The ability to do work (Metric Unit: Joule or J). There are many forms of energy, and it can be transferred from one form to another

Exothermic Reaction

The energy of the system decreases, and energy is released into the surroundings

Heat

Transfer of energy between two objects with different temperatures (in Joules)

State function

A property that describes an object’s current condition (doesn’t depend on how it got there). Total energy is a state function but work is not a state function because it depends on the pathway, as well as heat

Heating Curve

Temperature of system vs. amount of heat added. Temperature stops at the points where substance changes state

Spontaneous Reactions

Reaction will occur within a certain set of conditions. If a reaction can increase in entropy, it will likely be spontaneous

Work

Force exerted over a distance (Joules)

standard thermodynamic temperature

25˚C or 298.15 K.

Calculations on Enthalpy Changes for a chemical reaction

Delta H of reaction= Delta Hf products - delta Hf reactants

Specific Heat

* Amount of energy needed to raise the temperature of 1 gram of an object by 1 degree celsius
* A high specific heat means that the object requires a lot of energy to change temperature
* Water has a high specific heat, metals have low specific heat

Temperature Changes

q=m\*c\*deltaT

○ Used to figure out how much energy is required ○ Q = Energy

○ m = Mass

○ c = Specific Heat Capacity

○ Delta t= Change in Temperature

First Law of Thermodynamics

Energy can neither be created nor destroyed. It can only change forms. In any process, the total energy of the universe remains the same.

○ DeltaU = q+w

■ Delta U is the total change in internal energy of a system

■ q is the heat exchanged between the system and its surroundings

■ w is the work done by or on the system

* Any work or system that goes into or out of a system changes the internal energy
* ■ Energy is never created nor destroyed, the change in internal energy always is 0

If energy was absorbed into a system, than the energy was released into the surroundings

* Delta Usystem = - Delta Usurroundings

● Delta Usystem is the total internal energy

● Delta Usurroundings is the total energy of the surroundings

Second Law of Thermodynamics

○ Heat energy can’t be transferred from a body at a lower temperature to a body with higher temperature without the addition of energy

○ Delta Suniverse = Delta Ssystem+ Delta Ssurroundings > 0

Gibbs’ Free Energy

■ Delta H is the heat change for a reaction

■ Delta G is the measure of change of a system’s free energy in which a reaction takes place at constant temperature and pressure