Phase Petrology 1

Question 1

Gibbs Free Energy

Answer 1

A thermodynamic potential, which calculates the maximum of reversible work that a thermodynamic system may perform at a constant temperature and pressure.

Question 2

What types of phase diagrams are there?

Answer 2

Unary system: 1 Component
Binary system: 2 Components, P constant
Ternary system:3 Components P constant
Pseudo-ternary system: >3 Components, P constant

Question 3

Uses of phase diagrams

Answer 3

Modelling crystallization (Predicting sequences of cooling magma)
Modelling melting (Predict melt compositions)

Question 4

Energy

Answer 4

Energy provides the capacity to do work
(Force * Distance [ J ])

Question 5

System

Answer 5

A portion of the universe you want to study

Isolated: No exchange of heat or mass with surroundings

Closed: No exchange of mass with surroundings

Open: Exchange of heat and mass freely

Question 6

Phase

Answer 6

Any part of a system that is physically distinct and mechanically separable (Minerals, melts, vapour)

NOT the state of matter ie. liquid, solid

Question 7

Components

Answer 7

Minimum number of independent chemical compounds to describe the composition of all phases in the system

Question 8

How can a system with the composition CaMgSi2O6 be broken down in components?

Answer 8

Unary:CaMgSi2O6
Binary:CaSiO3, MgSiO3
Ternary:SiO2,MgO,CaO
Quaternary:Ca,Si,Mg,O

Question 9

Equilibrium

Answer 9

The minimum energy state of a system under imposed conditions. T, P and phase compositions are constant throughout the system.