1. An Oscillating Chemical Reaction What the heck?

2. What do we know about RXNs right now? If a chemical system is undisturbed, reactants should disappear and products should appear in a continuous manner until equilibrium is reached.

3. How do we produce an oscillating reaction? We must start with a concentration of reactants that is VERY different from the equilibrium values. There must be at least two competing pathways for the overall reaction. If Pathway 1 creates a product that is used as a reactant in Pathway 2, then that one reagent will act as a “trigger” for both reactions.

4. Pathway 1 2BrO 3 - + 12H + 10Mn 2+  Br - + 10Mn 3+ + 6H 2 O

5. Pathway 2 BrO 3 - + 5Br - + 6H +  3Br 2 + 3H 2 O

6. How do we Manipulate RXNS? LeChateliers Principle: – When a stress is added to a reaction, the reaction will shift to correct the imbalance created by the stress. – What is a stress? Change in concentration Change in temperature Change in pressure (REMEMBER: ONLY AFFECTS GASES)

7. Concentration An increase in concentration of any reactant or product will shift the reaction AWAY from the increase. A decrease in concentration of any reactant or product will shift the reaction TOWARDS the decrease. Heat + NH 4 Cl (s) ↔ NH 3(g) + HCl (g)

8. Temperature Reactions are either endothermic or exothermic Temperature is represented by energy on the reactant or product side Principle is same as concentration Heat + NH 4 Cl (s) ↔ NH 3(g) + HCl (g)

9. Pressure Only affects gases An increase in pressure shifts the reaction towards the side with the FEWER number of particles. 2H 2(g) + O 2(g) ↔ 2H 2 O (g)