15.1 Equilibrium and Equilibrium Constants
PRE-HEALTH PREP
Equilibrium
The rate of the forward reaction equals the rate of the reverse reaction.
Concentrations of reactants and products are not changing.
Equilibrium Constants (Law of Mass Action)
-Equals the ratio of the concentrations of products to the concentrations of reactants at equilibrium raised to the power of their coefficients.
-Only aqueous and gaseous species are included.
-Equilibrium constants are CONSTANTS; the value will only change with a change in temperature.
-An equilibrium constant also equals the ratio of the forward and reverse rate constants.
| EQUILIBRIUM CONSTANTS | |
|---|---|
| K >> 1 | Favors Products |
| K << 1 | Favors Reactants |
| 10-3 < K < 103 | Reactants and productsboth present at equilibrium |
2C(s) + O2(g) ⇌ 2CO(g)
Write the equilibrium constant expression (Kc and Kp) for the reaction above.
Kp vs Kc
Kp = Kc (RT)Δn Δn = change in moles gas R = 0.0821 L•atm/mol•K
If for 2C(s) + O2(g) ⇌ 2CO(g) Kc = 1200 at 400K, then what is the value of Kp?
2SO2(g) + O2(g) ⇌ 2SO3(g) Kc = 4.0
Based on the reaction above, what are the equilibrium constants for the following reactions?
2SO3(g) ⇌ 2SO2(g) + O2(g)
SO2(g) + ½O2(g) ⇌ SO3(g)
SO3(g) ⇌ SO2(g) + ½O2(g)