igneous petrology course lecturer: matt genge, meteorite researcher, previously worked at the...
TRANSCRIPT
Igneous Petrology Course
Lecturer: Matt Genge, Meteorite Researcher, Previously worked at The Natural History Museum.
Lectures: Part I (4 weeks) Igneous Processes at the Atomic Scale.Part II (4 weeks) Igneous Processes at Large Scales.
Practicals:How to recognise and describe igneous rocks in hand specimen and thin section (see list on handout sheet).
Coursework (20%):Five coursework pieces focused on each major group of igneous rocks.1.5 hour Exam (80%):Straight after christmas! Special revision session last practical.
Hot Under the Collar (part I)
Melting and the Phases of Matter
Pacaya Volcano - Guatemala
Igneous Rocks: formed by cooling of a magma.
The Four Phases of Matter
Liquid
Solid Gas
Plasma
Structural Differences
Configurational entropy (disorder)
Kinetic Differences
Vibrational entropy (disorder)
Entropy
The entropy of a mixture is higher than a pure material
Entropy
Entropy increases with temperature due to the magnitude of atomic vibrations
Entropy
Entropy is “wasted” or unavailable energy
Total Thermodynamic Energy in Matter
+Potential Energy Kinetic Energy
Total Energy (Enthalphy H) = PE + KE
Gibbs Free Energy
G – Gibbs Free Energy (energy available for chemical work)
H – Enthalpy (total energy)
S – Entropy (energy locked up in disorder – wasted energy)
G = H – T.S
First Law of Thermodynamics
Extrinsic and Intrinsic Properties
Extrinsic properties depend on the mass of the system.
Extrinsic and Intrinsic Properties
Intrinsic
Taste
Colour
Specific Gravity
Temperature
Extrinsic
Volume
Amount of Alcohol
Attractiveness
Extrinsic and Intrinsic Properties
Intrinsic
Composition
Temperature
Pressure
Extrinsic
Volume/mass
Enthalpy
Entropy
Gibbs Free Energy
Temperature
2
2
1
3
2mv
kT
• Temperature is the effect of the motions of atoms within a material (the vibrations, translations and rotations of molecules).
• Temperature is proportional to the average kinetic energy of the atoms or molecules within a material.
Pressure
V
NmvP
3
2
Pressure is the force applied by rebounding atoms and is related to the change in momentum.
Transitions between the Phases of Matter
Transitions and Gibbs Free Energy
•The phase with the lowest Gibbs Free Energy at equilibrium is the stable phase.
•Two coexisting phases have the same Gibbs Free Energy
Melting
Sudden increase in disorder on melting. A discontinuous increase in entropy S.
First & Second Order Phase Transitions
G = H – T.S• H is the latent heat of fusion
• Temperature stays constant until all the material has melted.