1. Quantifying Heat The Math!

2. What is HEAT?  It’s the flow of energy due to a difference in temperature.  From a higher temperature (higher kinetic energy) to a lower temperature (less kinetic energy)  THERE IS NO SUCH THING AS COLD!  It’s just the absence of heat!

3. Equation q = mCΔT heat energy – measured in joules (J) mass - measured in grams (g) heat capacity – how much heat a substance can hold, measured in joules/gram  degrees Celsius change in temperature, measured in °C ΔT = T final – T initial

4. Units for heat (q)  Most food tells us the amount of energy in units of Calories....  Calories are kilocalories ( 1 Cal = 1000cal )  The SI unit for energy is Joules (J)  1 cal = 4.184 J  Let’s do some quick conversions.

5. How does heat move? From areas of higher temperature to lower temperature! Endothermic Processes  Occur when heat is added to the system  Examples  Cooking  Evaporation  Instant cold packs Exothermic Processes  Occur when heat is given off by the system  Examples  Instant heat packs  Nuclear fission  Candle burning

6. Exo- or Endo- thermic?

7. How can you tell if a process is endothermic or exothermic? Endothermic  q is a positive number  Why?  The final temperature is higher than the initial temperature- we added heat to the system.  ΔT = T final – T initial Exothermic  q is a negative number  Why?  The final temperature is lower than the initial temperature- heat was given off from the system.  ΔT = T final – T initial Let’s solve some problems!