1. Combustion of Alkanes

2. Combustion of alkanes as typical hydrocarbons
Burning Produces CO2 and H2O and heat energy
if there is insufficient O2 then CO and even C [soot] can be formed at the same time
Dangers of CO
Incomplete combustion of organic compounds produces CO

3. CO is a cumulative poison
Combines with haemoglobin [Hb] where oxygen should go
Gets stuck there so Hb is no longer of any use for carrying O2
It take about 30 days before the red blood cell [Hb] is broken down and replaced with fresh Hb.
Colourless, odourless and tasteless
H2S is much more poisonous but much less dangerous because it smells

4. Combustion of Methane CH4(g) + 2 O2(g) = CO2(g) + 2 H2O(g)
ΔH = -880 kJ mol-1
CH4(g) O2(g) = CO2(g) + 2 H2O(l)
ΔH = -921 kJ mol-1
Difference is because the heat released when water turns from gas to liquid is added to the value. [This is a negative value.]

5. Heat of Reaction
Heat change when the number of moles in the balanced equation react compleatly.
[i] H2(g) + 1/2 O2(g) = H2O(g) H = -242 kJ
[ii] 2 H2(g) O2(g) = 2 H2O(g) H = -484 kJ
[iii] H2(g) + 1/2 O2(g) = H2O(l) H = -282 kJ
Value greater in equation [iii] because heat produced as water turns from steam to liquid water.

6. Combustion of Alkenes and Alkynes
C2H2(g) + 21/2 O2(g) = 2CO2(g) + H2O(g) ethyne
C2H4(g) O2(g) = 2CO2(g) + 2H2O(g)
ethene