AP Chemistry - Entropy, Enthalpy, and Free Energy

Open System

Energy and matter can be transferred

Closed System

Only energy can be transferred

Isolated System

Neither energy nor mass can be transferred

Isothermal

System kept at constant temperature by adding or subtracting heat from the surroundings

Calorie

Amount of heat required to raise the temperature of 1g of water by 1°C

4.18 Joules

1 calorie equals...

4.18

Specific Heat of Water in J/°C*g

1.00

Specific Heat of Air in J/°C*g

Heat Energy (Q)

(specific heat)(mass)(change in temperature) = ...

Energy

The capacity to do work and/or transfer heat.

Enthalpy (delta H)

Amount of heat released or absorbed by a chemical reacton at constant pressure

Endothermic

+Delta H

Exothermic

-Delta H

Standard Enthalpy of Formation

Amount of heat absorbed or released in which one mole of a substance is formed from its elements in their standard states, A.K.A. Heat of Formation

Hess's Law

Overall heat of reaction is equal to the sum of the heat of formation of the products minus the sum of the heat of formation of the reactants.

Internal Energy

Delta E; All the energy contained within a material

Internal Energy

Heat + Work = ...

+q

Heat added to the system (adds energy)

-q

Heat removed (removes energy)

+w

Work done on system (adds energy)

-w

Work done by system (removes energy)

Enthalpy

(delta E) + (delta n)RT = ...

Entropy

Dispersal of energy and matter

Higher entropy

Greater disorder (adding heat)

Increase

(Increase/Decrease in Entropy)
Solid to Liquid, or Gas to Solid

Increase

(Increase/Decrease in Entropy)
Solid or Liquid dissolves in a solvent

Increase

(Increase/Decrease in Entropy)
Number of particles in a system increase

Decrease

(Increase/Decrease in Entropy)
Decrease in temperature

Decrease

(Increase/Decrease in Entropy)
Mass of a molecule decreases

Higher

(Higher/Lower Entropy)
Weakly bonded compounds

Lower

(Higher/Lower Entropy)
Covalently bonded compounds

Higher

(Higher/Lower Entropy)
More complex molecules

Spontaneous

Process that takes place without net input of energy from an external source

Gibbs Free Energy (delta G°)

(delta H°) - T(delta S°) = ...

Free Energy

Amount of energy available to do work once you have paid your price to entropy

Spontaneous

(Spontaneous/Non-Spontaneous)
Negative delta G; Exoergic (Energy Releasing)

Non-Spontaneous

(Spontaneous/Non-Spontaneous)
Positive delta G; Endoergic (Energy Absorbing)