Kinetics Reaction Rates

1
Kinetics/ Reaction Rates

• Chapter 17

2
Reaction Rates

• Expressing Reaction Rate
• Collision Theory
• 1)
• 2)
• 3)

3
Reaction Rates

• activated complex
• activation energy
• Spontaneity implies nothing about reaction
  rate.

4
Factors Affecting Reaction Rate

• Nature of Reactants
• Concentration
• Surface Area

5
Factors Affecting Reaction Rate

• Temperature

6
Factors Affecting Reaction Rate

• Catalysts

7
Chapter 18 Chemical Equilibrium

• Law of Chemical Equilibrium - _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.
• aA bB ? cC dD

8
Chapter 18 Chemical Equilibrium

• Law of Chemical Equilibrium - _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.
• aA bB ? cC dD
• K
• Fwd Rxn Rate Rvs Rxn Rate
• At start
• As rxn
• proceeds

9
Chapter 18 Chemical Equilibrium

• Interpreting the value of K
• K (very large)
• K
• K (very small)

10
Chapter 18 Chemical Equilibrium
11
Chapter 18 Chemical Equilibrium
12
Determining the Value of the Equilibrium Constant

• H2 (g) I2 (g) ? 2 HI(g)
• K
• If at equilibrium H2 0.5225 M
• I2 0.5225 M
• HI 3.8950 M
• K ?

13
Determining the Value of the Equilibrium Constant

• A reaction chamber contains 1.00 M of H2, I2, HI.
  It is found that when the reaction reaches
  equilibrium, the concentration of HI is 1.7515 M.
  What is the value of the equilibrium constant?
• H2 (g) I2 (g) ? 2 HI(g)
• 1.00 1.00 1.00 (all units M)
• 1.8682 M

14
Determining the Value of the Equilibrium Constant

• A reaction chamber contains 1.00 M of H2, 2.00 M
  I2. It is found that when the reaction reaches
  equilibrium, the concentration of HI is 1.8682 M.
  What is the value of the equilibrium constant?
• H2 (g) I2 (g) ? 2 HI(g)
• 1.00 2.00 0.00 (all units M)
• 1.8682 M

15
Determining the Value of the Equilibrium Constant

• If the equilibrium concentrations of H2 and HI
  are 0.300 M and 4.20 M respectively, what must be
  the concentration of I2?
• H2 (g) I2 (g) ? 2 HI(g)
• 0.300 ? 4.20 M

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Factors Affecting Equilibrium

• LeChateliers Principle

17
Factors Affecting Equilibrium

• DEMO SUMMARY
• Concentration Change
• Volume (Pressure) Change
• Temperature Change

18
Solubility Equilibrium

• BaSO4 (s) ? Ba2(aq) SO42-(aq)
• K large (gt10)
• K 1
• K small (lt0.10)
• Solubility

19
Determining Solubility (Given Ksp)

• STEPS
• Write the dissolving equation for the compound
• Let s the concentration of the compound that
  can dissolve
• Write the equilibrium law expression
• Plug the value of K and the ion concentrations
  (in terms of s) into the expression and solve for
  s.

20
Determining Solubility (Given Ksp)

• Whats the solubility of AgI?
• (Ksp 8.5 x 10-17)

21
Determining Solubility (Given Ksp)

• Whats the solubility of Mg(OH)2?
• (Ksp 5.6 x 10-12)

22
Determining Solubility (Given Ksp)

• Whats the solubility of Ag2CO3?
• (Ksp 8.5 x 10-12)

23
Determining Ksp (Given Solubility)

• STEPS
• Write the dissolving equation for the compound
• Determine the concentration each ion given the
  solubility
• Write the equilibrium law expression
• Plug the ion concentrations into the expression
  and solve for Ksp.

24
Determining Ksp (Given Solubility)

• Whats the Ksp for AgCl?
• (Solubility )

25
Determining Ksp (Given Solubility)

• Whats the Ksp for PbCl2?
• (Solubility )