40 likes | 153 Views
Quantifying Heat. The Math!. Equation. c hange in temperature, measured in °C ΔT = T final – T initial. heat energy – measured in joules (J). h eat capacity – how much heat a substance can hold, measured in joules/ gram degrees Celsius. mass - measured in grams (g). q = mCΔT.
E N D
Quantifying Heat The Math!
Equation change in temperature, measured in °C ΔT = Tfinal – Tinitial heat energy – measured in joules (J) heat capacity – how much heat a substance can hold, measured in joules/gramdegrees Celsius mass - measured in grams (g) q = mCΔT
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.
How can you tell if a process is endothermic or exothermic? Endothermic Exothermic q is a negative number Why? The final temperature is lower than the initial temperature- heat was given off from the system. ΔT = Tfinal – Tinitial • q is a positive number • Why? • The final temperature is higher than the initial temperature- we added heat to the system. • ΔT = Tfinal – Tinitial Let’s solve some problems!