13.3Equilibrium Constants
Section · module m71834
What this needs
Learn these first — this section will not make sense without them.
Deriving Kp = Kc(RT)^Δn requires collapsing (RT)^(c+d) / (RT)^(a+b) into (RT)^Δn — the quotient-of-powers rule with a same base — and Δn can be negative, which is where the exponent sign gets dropped by mistake.
Coupled-equilibria manipulation is pure exponent-rule work on K values: reversing a reaction inverts K (Kc' = 1/Kc), scaling coefficients by x raises K to the x power (Kc' = Kc^x), and summing reactions multiplies the K values — three separate exponent-and-product rules the worked example (NH3/I2/HI) applies in sequence.
Qc and Kc are rational expressions built from bracketed concentrations raised to stoichiometric powers, e.g. Qc = [C]^x[D]^y / [A]^m[B]^n — a student who cannot read or simplify a rational expression cannot write the expression at all, let alone evaluate it.
What this touches
Algebra that turns up here. Not a blocker, but this is where you will see it used.
No algebra turns up here. Most of the descriptive sections need none.