Unformatted text preview: um constant (Keq) is a value representing the unchanging concentrations of the reactants and the products in a chemical reaction at equilibrium.
· For the general react ion ˆˆ
a A + b B ‡ˆ† c C + d D at a given temperature, K eq = d
[C]c [D] [A]a [B]b Examples: Write equilibrium constant expressio n (Keq) for each react ion shown below: 1. ˆˆ
3 H2 (g) + N2 (g) ‡ˆ† 2 NH3 (g) Keq = 2. ˆ ˆˆ
4 NH3 (g) + 3 O2 (g) ‡ˆ† 2 N2 (g) + 6 H2O (g) Keq = 9 Chemistry 52 Chapter 16 EQUILIBRIUM CONSTANTS
· The magnitude of an equilibrium constant indicates the extent to which the forward and reverse react ions take place.
· When Keq is large, it indicates more product than reactant is present at equilibrium. H2 (g) + I2 (g) ¾ ¾ 2 HI (g) ¬®
¾ Keq = 54.8 at 425 °C
More product than reactant is present at equilibrium · When Keq is small, it indicates more reactant than product is present at equilibrium. ¾
COCl2 (g) ¬¾ CO (g) + Cl2 (g) ¾ –
Keq = 7.6x10 4 at 400 °C More react...
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