# 6 - Gibbs phase rule Gibbs phase rule,was proposed by Josiah Willard Gibbs in the 1870s F=CP 2 where P alternatively or is the number of phases in

This preview shows pages 1–9. Sign up to view the full content.

Gibbs' phase rule

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Gibbs' phase rule ,was proposed by Josiah Willard Gibbs in the 1870s
F = C − P + 2 where P ( alternatively π or Φ) is the number of phases in thermodynamic equilibrium with each other C is the number of components . F is the number of degrees of freedom , which means the number of intensive properties such as temperature or pressure , which are independent of other intensive variables.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Phase: Pure substances – one species.(1) Mixture of gases – all gases mix freely.(1) Miscible liquids – two complete miscible liquid.(1) Non-miscible liquids – two separate layers. (2) Aqueous solutions – (1) Mixture of solids – consists of different properties. (2) or (3) Components: Water [ice, water, vapor] and Sulfur [rhombic, monoclinic, liquid, vapor – (1) Mixture of gases – Two components (2) Sodium chloride solution – NaCl. H 2 O – (2) Degree of freedom: Least no. of variables factors (temp, pressure and conc.) which must be specified so that the remaining variables are fixed automatically and the system is completely defined. F = 0 – nonvariant or no degree of freedom – pressure and temp - fixed F = 1 – univariant or one degree of freedom – either pressure or temp - fixed F = 2 – bivariant or two degree of freedom – both pressure and temp - variable
In F = C – P + 2 For pure substances C = 1 so that F = 3 – P . In a single phase ( P =1) condition of a pure component system then, F = 3 – 1 = 2 (two variables), such as temperature and pressure. It can be controlled to any selected pair of values. If the pure component undergoes a separation into two phases (C = 1, P = 2), F = 1 – 2 + 2 gives F = 1 When the system enters the two phase region, it becomes no longer possible to independently control temperature and pressure

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Phase diagram Plot showing the conditions of pressure and temp under which two or more physical states can exist together in a state of dynamic equilibrium B C A O Sublimation curve Vaporization curve
Three characteristics features 1. Areas 2. Curves 3. Triple point Areas: - Solid, Liquid and vapor. (COB, COA and AOB) Curves: - Solid/liquid line (OC) – melting curve or fusion curve Liquid/vapor line (OA) – vapor pressure curve or vaporization curve for liquid Solid/vapor line (OB) – Sublimation line Triple point: - the conditions where all the three phases can exists in equilibrium.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
The phase boundary between liquid and gas does not continue indefinitely. Instead, it terminates at a point on the phase diagram called the critical point . At extremely high temperatures and pressures, the
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 06/06/2011 for the course CHEM 3040 taught by Professor Reddy during the Spring '10 term at Taylor's.

### Page1 / 41

6 - Gibbs phase rule Gibbs phase rule,was proposed by Josiah Willard Gibbs in the 1870s F=CP 2 where P alternatively or is the number of phases in

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online