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Chemistry

Limiting Reactant Calculator

Identify the limiting reactant from two available mole amounts and balanced reaction coefficients.

Explicit units and model assumptionsLocal calculations with worked examples
Chemistry workspace
Chemistry workspace

Check the units, concentration basis and assumptions before interpreting the result.

See the method

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Your chemistry result

Your result

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Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter reactant a available, a coefficient, reactant b available, b coefficient, product coefficient.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Reaction extent = min(nA/coefficient A, nB/coefficient B). Product amount = extent × product coefficient. Leftover amounts subtract each stoichiometric consumption.

A WORKED EXAMPLE

Using reactant a available = 3 mol, a coefficient = 2, reactant b available = 2 mol, b coefficient = 1, product coefficient = 2, the result is 3 mol product. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

The coefficient tells how many moles are consumed per reaction extent. The smaller available extent runs out first, limiting the product amount.

What to keep in mind

Models two reactants in one complete reaction; side reactions and equilibrium are excluded. Educational calculation only; use validated procedures for laboratory work.

Reference: OpenStax Chemistry 2e — chemical quantities and models

Common questions

Why divide moles by coefficients?

The coefficient tells how many moles are consumed per reaction extent. The smaller available extent runs out first, limiting the product amount.

Are my inputs uploaded?

No. This calculation runs in your browser without an account or an external API.

Methodology maintained by ClarityKit. How these tools are built and checked.