1. CHEMICAL PROPERTIES How reactive is a substance?
Chlorine gas, Cl2 is very reactive; produces acids with water.
What other substances does it react with?
It reacts with practically every other element.
E.g. Chlorine reacts with lime to neutralize it.
What are the products of this reaction?
Calcium hypochlorite and hydrogen chloride

2. CHEMICAL REACTION (CR1)
Atoms in the initial substances (lime and chlorine = REACTANTS = R) are rearranged to produce a different set of final substances (calcium hypochlorite and hydrogen chloride = PRODUCTS = P)
R → P
This rearrangement requires bonds breaking in R and bonds forming in P

3. CHEMICAL REACTION (2)
Mass is conserved: Total mass of R = total mass of P.
Atomic identity is conserved: All atoms present in R are present in P. No atom is destroyed or created.

4. CHEMICAL EQUATION How do we write a chemical reaction?
A Chemical Equation is a shorthand description of chemical reaction.
We use Chemical Formulas (shorthand notation for substances) for R and P.
Ca(OH)2 + 2Cl2 → Ca(OCl)2 + 2HCl
note conservation of mass and atom identity
we call this a balanced chemical equation

5. CHEMICAL REACTION (3)
When a substance combines with oxygen, O2, we say that oxidation occurs.
oxidation of glucose (sugar) in body to produce CO2(g), H2O(ℓ) and, most importantly,energy
When a flame observed, we say that combustion occurs: solid carbon burns in oxygen gas to produce carbon dioxide gas.
C(s) + O2(g) → CO2(g) Is eqn balanced?

7. BALANCING A CHEM RXN Burning methane
CH4(g) + O2(g) → CO2(g) + H2O(ℓ)
R side:1C, 4H and 2O & P side: 1C, 2H and 3O
Balance H by adding another H2O
R side:1C, 4H and 2O & P side: 1C, 4H and 4O
Balance O by adding another O2
R side:1C, 4H and 4O & P side: 1C, 4H and 4O
CH4(g) + 2O2(g) → CO2(g) + 2H2O(ℓ)

8. BALANCING A CHEM RXN Burning methanol (1)
CH3OH(ℓ) + O2(g) → CO2(g) + H2O(ℓ)
R side:1C, 4H, 3O & P side: 1C, 2H, 3O
Balance H by adding another H2O
R side:1C, 4H, 3O & P side: 1C, 4H, 4O
Balance O by adding another 1/2 O2
R side:1C, 4H, 4O & P side: 1C, 4H, 4O
CH3OH(ℓ)+3/2 O2(g) → CO2(g) +2H2O(ℓ)

9. BALANCING A CHEM RXN Burning methanol (2)
CH3OH(ℓ)+3/2 O2(g) → CO2(g) +2H2O(ℓ)
R side:1C, 4H, 4O & P side: 1C, 4H, 4O
But we want to avoid half-molecules by multiplying by appropriate factor : 2 in this case.
2CH3OH(ℓ)+3O2(g) → 2CO2(g) +4H2O(ℓ)
R side:1C, 8H, 8O & P side: 2C, 8H, 8O

10. OXIDATION OF FOOD Sugar + oxygen → carbon dioxide + water + ENERGY
C6H12O6(s) + O2(g) → CO2(g) +2H2O(ℓ)
ENERGY: to sustain life, move, breathe, think, maintain body temp…

11. OTHER CHEM RXNS (1) Complete oxidation of CO Tarnishing of Silver, Ag
2CO + O2  2CO2 catalytic converter
Platinum, Pt, is the catalyst
Tarnishing of Silver, Ag
2Ag + H2S  Ag2S + H2
Rusting of Iron, Fe (oxidation)
4Fe + 3O2  2Fe2O3

12. OTHER CHEM RXNS (2) Production of Ammonia, NH3 Airbags
N H2  2NH3
Highest volume industrial compound
Fritz Haber
High temp and pressure, with catalyst
Fertilizer, explosives, refrigerant
Airbags
2NaN3(s)  2Na(s) N2(g)
Rusting of Iron, Fe (oxidation)
4Fe + 3O2  2Fe2O3