CO2 Carbon Dioxide is the chemical most involved in global warming. It requires a large amount of energy to break the bonds. The sun’s rays vibrate the molecule warming the air around it. This creates a convection effect warming the planet.

Chemical Equation CH4 + 2 O2 → CO2 + 2 H2O This is a combustion reaction Carbon Compound (CH4) + O2  CO2 + 2 H2O

Molar Mass CO2 Carbon has an atomic mass of 12 a.m.u. O has an atomic mass of 16 a.m.u. There are 2 Oxygen atoms in CO2 2 X 16 = 32 12 + 32 = 44

Dot Diagram Each dot represents a valence electron C O O Each bond requires 2 electrons. Each bar represents a bond. O C O

O C O Bond Types There is only one type of bond in this chemical Oxygen / Carbon double bond Both of these atoms are non-metals When non-metals bond they form covalent bonds.

Electronegativity Ionic 1.7 - 4.0 Polar Covalent 0.5 - 1.69 Non-Polar Covalent 0.0 – 0.49 (Oen - Cen) 3.55 – 2.55 = 1 Polar covalent bond Oxygen holds electrons tighter than Carbon

Bond Energy Calculating Enthalpy Reactants Products Bonds breaking are negative and bonds forming are positive CH4 + 2 O2 → CO2 + 2 H2O C-H O=O C=O H-O Reactants -424 x4 = -1696 (C-H) -495 x2 = -960 (O=O) - 2686 (kJ/mol) Products 1072 x2 = 2144 (C=O) 463 x2 = 926 (O-H) 3070 (kJ/mol) Exothermic: energy is released enthalpy of reaction is negative Endothermic: energy is absorbed enthalpy of reaction is positive

Endothermic vs Exothermic Exothermic: energy is released enthalpy of reaction is negative Endothermic: energy is absorbed enthalpy of reaction is positive Reactants -424 x4 = -1696 (C-H) -495 x2 = -960 (O=O) - 2686 (kJ/mol) Products 1072 x2 = 2144 (C=O) 463 x2 = 926 (O-H) 3070 (kJ/mol) SUM (BEreactants) - SUM (BEproducts) = Hreaction 3070 - 2686 = 384 (kJ/mole) 384 is a positive (+) number This is an exothermic reaction