Thermodynamics : an introduction

FMIPA UGM – September 2020

Niko Prasetyo

Outline Termodinamika Kimia

Lecture and reading materials :

At this classroom

Ugm.id/1ND

Elok (still in preparation)

Mid exam

Open Book (not open google), no multiple choice!

Do it by yourself!

Main reference :

Peter Atkins, Physical Chemistry 9th Edition

ThermodynamicsThermodynamics parameters :

U G H S A q W

thermodynamics Heat, work and energy

In thermodynamics, the universe is divided into two parts

System : the world which has special interest (engine, electrochemical cell and so on)

Surroundings : region outside the system and are where we make our measurements

There is a boundary between system and its surroundings

Typically, there are 3 types of the boundary

thermodynamics Heat, work and energy

thermodynamics Heat, work and energy

basic definition

Work (w): ability to achieve motion against an opposing force

Example : expansion of gases that pushes out a piston ; raising a weight against the pull of gravity

Energy (E): capacity to do work. When system does work, the energy of the system is reduced

Heat (q) : when the energy of a system changes as a result of temperature difference between system and surroundings, the energy is transferred as heat

Exothermic process : system -> surroundings

Endothermic process : surroundings -> system

thermodynamics Heat, work and energy

basic definition

thermodynamics Heat, work and energy

● The sign of q in an exothermic process is negative because system is losing heat

(A) In an endothermic reaction, heat flows from the surroundings into the system, decreasing the temperature of the

surroundings. (B) In an exothermic reaction, heat flows from the system into the surroundings, increasing the

temperature of the surroundings.

thermodynamics Heat, work and energy

basic definition

thermodynamics Heat, work and energy

Application

● Bomb calorimeter

● Constant volume

● qcal=ChardwareΔT+ mwaterCs,waterΔT

● The measured heat is equivalent

with the change of internal energy (U)

● Conversion to entalphy, required work (w)

thermodynamics Heat, work and energy

Energy ( Joule ; cal ; (kg . m2 /s2) ) )

r

thermodynamics Heat, work and energy

Energy ( Joule ; cal ; (kg . m2 /s2) ) )

● There a lot of manifestations of energy

● potential energy is the most important

● The potential energy V of a system determines which structures are likely/unlikely to be observed

Terima kasih!

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