wunder beta

⚗️ Writing Equilibrium Constant Expressions

Turn balanced reversible equations into equilibrium expressions, choose concentrations or partial pressures, omit pure phases, and use Q to predict the direction of change.

lessons

~10 min

to learn

🔬 Science

subject

Adults

level

Start the course →

What you’ll learn

Build the expressionTranslate a balanced reversible equation into a concentration-based equilibrium expression.Place products over reactants and use balanced coefficients as exponents.
Handle special casesDistinguish formula subscripts from equation coefficients and omit pure phases correctly.Keep species and coefficients separate, then leave pure solids and liquids out of the expression.
Compare forms and directionsChoose Kc or Kp and use Q compared with K to reason about net change.Match the expression to the data and interpret whether the system shifts forward or backward.
Audit and interpretCheck an equilibrium expression and explain what its value says about composition.Use a repeatable audit, then separate equilibrium position from reaction speed.

Questions this course answers

For 2NO2(g) reversible to N2O4(g), what is Kc?

Products go in the numerator, and the coefficient 2 on NO2 becomes its exponent.

Which species is omitted from an equilibrium expression?

Pure solids have constant activity and are not written in the ordinary expression.

What becomes an exponent?

Coefficients in the balanced equation become powers in K or Q.

What is true at equilibrium?

At a fixed temperature, the reaction quotient reaches the equilibrium constant.

Grounded in trusted sources

[object Object]
[object Object]
[object Object]
[object Object]

Every Wunder lesson is built from real, reputable sources — never invented.

Related Science courses

⚗️How Chemical Equilibria Shift 🧪Balancing Acid-Base Equations 🧪How the Henderson-Hasselbalch Equation Works Ã¢Å¡Â¡How to Calculate Standard Cell Potential 🧪How to Calculate Percent Error 📈Reading Calibration Curves 🔬How to Pipette Accurately Ã°Å¸Â§ÂªHow to Use a Spectrophotometer

Wunder is a personalized learn-anything platform — tell it any topic and it builds a beautiful, fact-checked course in minutes, with narration, a knowledge check, and a college-style University track.

Browse more Science courses · All topics · Home