+

Chemical Energy

+Hmmm…

Can you list 5 energy sources that do not directly produce carbon dioxide?

+ Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O

What type of reaction does this look like?

Where would energy go in this reaction?

+

Fossil Fuels Why can fossil fuels be considered as a stored solar energy source?

+Types of Energy

Kinetic Energy = energy of motion

Thermal Energy = heat = movement of particles

Potential Energy = stored

+ Heat

Heat = thermal = kinetic energy

(using the definitions from the previous slide, explain to your partner how this could be)

+q = mcΔt (heat formula) q = heat, kinetic energy (J or kJ)

m = mass

c = specific heat capacity – amount of energy involved in changing the temperature of 1g of a substance by 1oC

Δt = change in temperature

+Think About THIS!

If you are heating water and metal at the same temperature, which one will heat up faster? Why?

How do we relate that to Heat Capacity?!

+EXOTHERMIC CHANGE

System loses energy

+ENDOTHERMIC CHANGE

System gains energy

+Example:

Calculate the energy released when 250mL of water cools down from 98.0C to 25.0C.

(c for water = 4.19J/g/C)

+Example 2:

Calculate the heat capacity of a pot that water is heated in when the energy required to heat the 300gram pot from 12C to 112C is 11.7kJ.

+Remember:

Endothermic reactions energy is ABSORBED (surroundings get cooler)

Exothermic reaction energy is RELEASED (surroundings get warmer)

+

Enthalpy Enthalpy involves only changes in POTENTIAL ENERGY

changes in bond energy

+ 3 types of enthalpy changes (Ep) phase change – intermolecular bonds (forces)

chemical change – intramolecular bonds (ionic / covalent)

nuclear change – protons and neutrons are altered

+For tomorrow…

How can we relate HEAT or Thermal energy to ENTHALPY????