3.  There are several factors affect reaction rates ◦ Concentration ◦ Surface area (Particle size) ◦ Temperature ◦ Catalysts ◦ Inhibitors

6.  A catalyst is a substance that increases the rate of a chemical reaction without itself being used up in the reaction.  A catalysts provide an alternative energy pathway for the reaction.  The different pathway lowers the activation energy allowing more molecules to overcome the activation energy and produce products at a faster rate

7. HH A lower activation energy allows more molecules to overcome the activation energy, speeding up the reaction Potential Energy

9.  An inhibitor is a substance that slows down, or inhibits reaction rates.  Uses ◦ A preservative ◦ A weed killer

11.  When a reaction results in complete conversion of reactants to products chemists say it goes to completion  Not all reactions go to completion. They appear to stop because they are reversible  Reversible reactions can occur in both the forward and reverse directions

12.  Forward N 2 + 3H 2  2NH 3 ◦ The reactants are N 2 and H 2  Reverse N 2 + 3H 2  2NH 3 ◦ The reactant is NH 3 N 2 + 3H 2 ⇆ 2NH 3 The forward and reverse reactions are happening at the same time.

13.  Chemical equilibrium is a state in which the forward and reverse reactions balance each other because they take place at equal rates. ◦ Rate forward reaction = Rate reverse reaction  This does not mean the concentrations of the products and reactants are the same  Equilibrium is a state of action, not inaction. This process is dynamic; dynamic equilibrium.

14.  http://www.youtube.com/watch?v=JsoawKg uU6A http://www.youtube.com/watch?v=JsoawKg uU6A

15.  Law of chemical equilibrium states that at a given temperature, a chemical system may reach a state in which a particular ratio of reactant and product concentrations has a constant value known as Keq or equilibrium constant.

16.  Keq is the ratio of product concentrations to reactant concentrations.  A large Keq, Keq > 1 means the products are favored over the reactants  A small Keq, Keq < 1 means the reactants are favored over the products

17.  Homogenous equilibrium means all reactants and products are in the same physical state  Ex: H 2 (g) + O 2 (g)  H 2 0(g)  Heterogeneous equilibrium is when the reactants and products are in more than one physical state.  Ex: H 2 O(g) + C(s)  H 2 (g) + CO(g)

18. aA + bB  cC +dD products [C] c [D] d reactants [A] a [B] b == K eq **only use K eq for gases and aqueous compounds

19. 1. Given N 2 (g) + 3H 2 (g)  2NH 3 (g) write the equilibrium constant expression for the reaction.

20. 2. Given SO 2 (g) + O 2 (g)  2SO 3 (g) write the equilibrium constant expression for the reaction.

21. 1. Given 2NaHCO 3 (s)  Na 2 CO 3 (s) + CO 2 (g) + 3H 2 O (g) write the equilibrium constant expression for the reaction.

22. At equilibrium and 100°C a flask contains: [PCl 5 ]=0.0325M[H 2 O]=0.025M [HCl]=0.375M[POCl 3 ]=0.250M Calculate the K eq for the reaction PCl 5 (g) + H 2 0 (g)  2HCl (g) + POCl 3 (g)