Relative Volatility Calculator
Enter equilibrium distribution ratios Ki = yi/xi and Kj = yj/xj for two components at the same temperature and pressure. This educational ratio does not predict separation performance.
A QUICK WALKTHROUGH
How to use this tool
- Enter your own values in the units shown.
- State the shared temperature and pressure basis with units.
- Calculate the estimate. Editing inputs clears the previous result.
Formula and scope
αij = Ki / Kj. Both K values must be finite and positive and use the same equilibrium temperature, pressure, and phase convention. αij describes component i relative to component j; reversing the order gives its reciprocal. αij = 1 means equal K values under the entered conditions. K values are user supplied; no temperature/pressure adjustment, composition model, column sizing, or separation performance is calculated.
Educational reference
Perry’s Chemical Engineers’ Handbook, seventh edition, section 13, Distillation (CMU-hosted educational reference): https://schneider.cheme.cmu.edu/Files/Perry%27s%20Chemical%20Engineers%27%20Handbook%207th%20Edition/13.%20Distillation.pdf. Educational equation context only; no source implementation is copied.
Browser privacy
Inputs and results stay in this browser tab. Nothing is uploaded or stored by this calculator.
GOOD TO KNOW
Common questions
Where do the input values come from?
You supply every value and are responsible for its units, definition and conditions. No material properties or operating values are selected for you.
Does this provide an engineering design or safety assessment?
Both K values must be finite and positive and use the same equilibrium temperature, pressure, and phase convention. αij describes component i relative to component j; reversing the order gives its reciprocal. αij = 1 means equal K values under the entered conditions. K values are user supplied; no temperature/pressure adjustment, composition model, column sizing, or separation performance is calculated.