WARM UP “All growth depends upon activity. There is no development physically or intellectually without effort, and effort means work.” – Calvin Coolidge 1. Do you agree with this? 2. How can you apply this to your life?

Energy Chemistry II

Energy Ability to do work Can be radiant, thermal, chemical, etc. – Heat = transfer of thermal energy Measured in joules (J) – Thermochemistry = study of energy in reactions

Energy Changes First Law of Thermodynamics (Law of Conservation of Energy) – Total amount of energy in the universe is constant – Energy can change form, but not be created or destroyed ΔE sys α Δ E surr

Energy Changes A system interacts with surroundings – Open system Heat and mass transfers – Closed system Heat transfer only – Isolated system No transfer

Calculating Energy Can analyze energy change (ΔE)in reactions ΔE = E final – E initial or Δ E = E products – E reactants Related to reaction equation – Based on moles (kJ/mol) – Altered with changing reactant/product amounts

Exothermic Reactions - Δ E – Products are lower energy than reactants Usually spontaneous – Heat is lost to surroundings (creates warmth) - Δ E system = + Δ E surroundings

Endothermic Reactions + Δ E – Products are higher energy than reactants Usually not spontaneous – Heat is absorbed by system (creates cold) + Δ E system = - Δ E surroundings

Calculating Energy Δ E = q + w – Change in energy = heat + work All units are joules – q is negative if heat is lost – w is negative if work is done

WRAP UP State the first law of thermodynamics in one good sentence.