Energy

• The Ability to do work
  
• Bonds store chemical energy (break bond=release, make bond=use energy)
• Kinetic Energy: energy in motion
• Potential Energy: stored energy

Heat

• The amount of the thermal energy
  
• Extensive
  

Temperature

• Measurement of average kinetic energy of a substance
  
  
• Intensive
  
  

Law of conservation of energy: energy can be neither created or destroyed, only transferred into different forms
1st law of thermodynamics: the energy of the universe is constant
Heat (total thermal energy/depends on amount) vs. Temperature (measure of average kinetic energy)

Exothermic-heat is transfered from a system to the surroundings. (Positive q)
Endothermic-heat is transfered from the surroundings to a system. (Negative q)

(when graph above has a slope)
q = mC(ΔT)
q is the heat transferred (J)
C is the specific heat capacity (J/g*K)
m is the mass of substance (g)
delta "t" is the change in temperature (K)

(when graph above slope is 0 )
q= mL
m is the mass of the substance (g).
L is either the latent heat of fusion or vaporization, depending on if the substance is melting or freezing. Can also be notated as ΔH (J/g)


· Sum of the heat content changes within a given system is zero

Energy Units

1 Joule = 1 kgm^2/s^2
1 calorie = 1 cal = 4.184 J
1 Calorie = 1000 cal = 1 kcal = 4184 J = 4.184 kJ (food calorie)

HH
Specific Heat Capacity (c): the amount of energy required to raise the temperature of one gram of the substance 1 K (Units: J/gK)

Energy is transferred between system and surroundings only as heat or work

system expands --> does work and is negative
system contracts --> work is done upon it and is positive

*Standard State-Most stable form of a substance in the physical state that exists at a pressure of 1 bar and at a specified temperature (usually 25 degrees celcius or 298 K).

Enthalpy Change - state function (Not dependent on path taken, only final/starting conditions)

1) When you reverse an equation, the magnitude of enthalpy change is the same but the sign is opposite.

2) Depends on number of moles (Ex. # of moles x 2 = enthalpy x 2)

3) State of matter specific


Hess's Law - If you add all of the delta H's up you get the delta H of the given equation.