1. 11.3 – NOTES Combustion

2. Exothermic reaction, therefore heat is released
B.6 Combustion
Burning is combustion
CxHy + O2  CO2 + H2O + energy
Exothermic reaction, therefore heat is released

3. Specific heat capacity
Shortened to specific heat
The amount of energy needed to raise 1 gram of something by 1°C
Water’s is 4.18 J/(gC)

4. Calculating energy using specific heat
The equation for these problems is Q = m * C * T
Q = thermal energy/heat
Joules (J), kilojoules (kJ) or calories (cal)
m = mass of the object in grams (g)
C = specific heat (J/g°C or cal/g°C)
ΔT = change in temperature = Tfinal - Tinitial (°C)
Δ = delta = change in _____________

5. Examples
How many joules of energy are given off when heating 12.5 g of water from 10 °C to 25 °C?
~ J

6. What is the specific heat of a substance that releases 250 J of energy when 10 g are heated 35°C?
~c = .714 J/g°C

7. Heat of combustion
Amount of energy given off when something burns
kJ/gram or J/gram
Molar heat of combustion
Amount of heat involved when burning 1 mole of something
Remember, 1 mole = 6.02 x 1023
kJ/mol or J/mol