Equation and purpose
Compare current state to equilibrium; predict direction.
\[Q = \frac{[C]^c[D]^d}{[A]^a[B]^b}_{non-eq}\]
Compare current state to equilibrium; predict direction.
REARRANGEMENTS
If Q<K→ forward, Q>K→reverse.
Dimensional check: same as K ✓
Variables and units
| Symbol | Quantity | Unit | Notes |
|---|---|---|---|
| Q | Q | — | — |
Conditions and limitations
Same expression as K but with non-equilibrium values.
Worked example
Q=2, K=10 → shift forward.
Reaction Quotient Q
Compare current state to equilibrium; predict direction.
Equation
Inline: $Q = \frac{[C]^c[D]^d}{[A]^a[B]^b}_{non-eq}$$
Variables
| Symbol | Quantity | Unit | Notes |
|---|---|---|---|
| reaction quotient | — | — |
Conditions and limitations
Same expression as K but with non-equilibrium values.
Rearrangements
If Q<K→ forward, Q>K→reverse.
Dimensional check: same as K ✓
Worked example
Q=2, K=10 → shift forward.
Steps: write equation → substitute with units → check dimensional consistency → report with correct significant figures.
Common errors
- Thinking Q=K always
Related resources
- chemical-equilibrium topic
- Calculators — linked only when a real calculator implements this formula.
- Constants — sourced constants with version when values are required.
Sources
- NIST Physical Constants 2022 — CODATA.
Reviewed 2026-08-21 by Editorial Team; due 2027-08-21.
Common errors
- Thinking Q=K always
RELATED FORMULAS
C
Chemistry Fundamentals Editorial TeamAuthor
E
Editorial Review BoardReviewer
Editorial Team — transparent review placeholder
Reviewed August 21, 2026
SOURCES
- [nist-2022]NIST Physical Constants 2022 (2022). NISThttps://physics.nist.gov/constants