# 110112 - First Law of Thermodynamics(Chapter 3 p 39-49 1st...

This preview shows pages 1–7. Sign up to view the full content.

1 CHM3400 - Lecture 4 Jan 12 First Law of Thermodynamics (Chapter 3 p. 39-49) 1 st Law of Thermodynamics State functions vs. path functions Enthalpy

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

View Full Document
2 Energy Forms of energy : 2 mc E = Mass (defect) energy: 2 2 1 mv E kin = Kinetic energy: Gravitational energy: mgh E = T k E B thermal 2 3 = Thermal energy: Photon energy: ν h E = Units?
3 First Law of Thermodynamics “Energy cannot be created or destroyed, it can only be converted from one form to another.” Law of conservation of energy : “The total energy of a closed system is conserved.” “The total energy of the Universe is conserved.” ( ) More difficult to prove

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

View Full Document
4 Energy transfer: w and q Transfer of energy can appear in two forms: Either through work ( w ) or heat ( q ) By convention, if : w,q = 0 : no energy transfer w,q > 0 : heat absorbed by the system ( endothermic reaction), work done on the system by the surroundings w,q < 0 : heat emitted by the system ( exothermic reaction), work done by the system Heat transfer = temperature change Work = ………………. . e.g. mechanical work here: (gas) expansion
5 Isothermal expansion A gas at initial state ( P 1 , V 1 , T ) is allowed to expand to a final state ( P 2 , V 2 , T ) while lifting a weight (mass = m ) over a distance Δ h . Δ h What is the work performed by the system? Actually very confusing example! Air???

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

View Full Document
6 Work performed for weighted piston The system is the gas that performs the work The environment is the weight on which the work is performed h mg h F env Δ = Δ = ϖ h mg env sys Δ = = w sys < 0: what does that mean?
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 27

110112 - First Law of Thermodynamics(Chapter 3 p 39-49 1st...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online