Calculate the equilibrium constant (Kc) or reaction quotient (Q) based on molar concentrations.
Reactants
M
M
Products
M
M
Calculation Results
Enter concentrations and coefficients to see results
Overview
Chemical equilibrium is a state of balance where reactions don't stop, but the forward and reverse rates become equal. It's like a busy store where customers enter and leave at the exact same rate—the number of people inside stays constant, even though the individuals change.
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Pro Tips
Pure solids (s) and liquids (l) are IGNORED in equilibrium expressions! Only use gases (g) and aqueous (aq) species.
If Kc > 1, the reaction favors products (goes to the right). If Kc < 1, it favors reactants (stays left).
Catalysts do NOT change the value of Kc; they just help the system reach equilibrium faster.
Temperature is the ONLY thing that changes the value of Kc. Pressure and concentration changes just shift the position to restore the same Kc.
Coefficients in the balanced chemical equation become exponents in the Kc formula. A coefficient of 2 means [Concentration]².
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Fun Facts
"Diamonds aren't forever! Graphite is actually the more stable form of carbon at equilibrium. Diamonds are just kinetically 'stuck' and transform into graphite... very, very slowly."
"Smog's brown color comes from Nitrogen Dioxide (NO₂), which exists in equilibrium with colorless Dinitrogen Tetroxide (N₂O₄). On hot days, the equilibrium shifts to form more brown NO₂."
"Your body relies on 'Homeostasis', a complex network of dynamic equilibria, to keep your blood pH, temperature, and sugar levels stable."
"Ocean acidification is equilibrium in action: CO₂ dissolves in water to form carbonic acid, shifting the balance and threatening marine life using calcium carbonate shells."
"Hemoglobin binds O₂ in your lungs (high O₂) and releases it in tissues (low O₂), perfectly following Le Châtelier's principle."
"The Haber Process uses high pressure to shift the equilibrium of Nitrogen + Hydrogen toward Ammonia, a discovery that feeds half the world's population through fertilizers."
"In a sealed soda bottle, CO₂ gas is in equilibrium with dissolved CO₂. Opening it breaks the equilibrium, and bubbles rush out to restore balance!"
