# What is thermodynamics?

#### ThermodynamicsEnergyEnergy 101Energy TransformationsKinetic & Potential Energy

Sounds complicated, right? If you think it's something aerospace scientists, such as NASA astronauts might know about; or something involved in the mechanical engineering of hybrid cars; or something biomedical scientists might use when making tissue, then you're right. In fact all scientists, including physicists, chemists and biologists, use thermodynamics in one way or another.

So what's the basic concept? Thermodynamics is the study of converting energy from heat into usable energy (e.g. work).

Did you know? Zeroth Law of Thermodynamics states that the temperature of an object in thermal equilibrium does not change over time.

The process of energy conversion is made up of several parts: temperature, enthalpy, energy and entropy. These parts are used to explain the concept of something called “Gibb’s free energy” or ΔG =ΔH –T ΔS (see below).

Energy (G) is a measure of work. It can be in the form of kinetic energy (e.g. active energy; the energy an object needs to start moving) or potential energy (e.g. stored energy; the energy of an object at rest).

Temperature (T) measures the average kinetic (active) energy of the molecules in a system.

Did you know? First Law of Thermodynamics: Energy is never created nor destroyed; instead Energy is transformed from one type (i.e. heat) to another type (i.e. work).

Molecules are constantly moving: at high temperature (e.g. hot water) the molecules are moving faster than the molecules at low temperature (e.g. cold water). However, when molecules from these two systems (high temperature and low temperature) come into contact with each other, energy is transferred between them. Molecules from a low temperature system will become warmer until both systems are the same temperature (e.g. thermal equilibrium).

Enthalpy (H) measures the amount of heat transferred between a system and the surrounding environment. If heat energy is given off, the system is "exothermic" (e.g. lighting a match). If heat is used up or is absorbed, the system is "endothermic" (e.g. melting snow).

Did you know? Second Law of Thermodynamics: The overall Entropy — the measure of disorder — will increase over time.

Entropy (S) measures disorder or chaos. If we look at water molecules, molecules at a high temperature (e.g. boiling water) move faster than those at low temperature (e.g. ice-cube). The entropy of boiling water is greater than the entropy of the cold water. As the ice cube melts, its entropy increases over time.

http://en.wikipedia.org/wiki/Thermodynamics

http://www.grc.nasa.gov/WWW/K-12/airplane/thermo.html

http://ocw.mit.edu/courses/chemistry/5-60-thermodynamics-kinetics-spring-2008/

http://en.wikipedia.org/wiki/Gibbs_free_energy

#### Narveen Jandu

Narveen is currently a Lecturer in Cell Biology and a Curriculum Fellow in Cancer Biology at Harvard Medical School. Prior to moving to Boston, she was a post-doctoral research fellow at Stanford University, where she was studying the interactive effects of gut microbes on immune cell homing and trafficking. Narveen received her PhD from the University of Toronto - her thesis was on the pathogenic effects of Escherichia coli O157:H7 on an innate immune signalling cascade of intestinal epithelial cells. Prior to her PhD training, she completed a Master's degree at McMaster University and she completed her undergraduate degree at Wilfrid Laurier University.