What Does a Negative Change in Entropy Indicate?

The overall entropy of the entire universe always increases.
••• Ablestock.com/AbleStock.com/Getty Images

The various forms of energy in the natural world have a tendency to spread out. A common example of this is heat: a warm loaf of fresh bread on a dinner table gradually releases its aromatic heat into the surroundings. This heat energy was localized and orderly inside the loaf of bread, then it became less localized and less orderly as it dispersed into the room. Scientists have a name for the disorderly dispersal of energy: entropy.

Restoring Order

Entropy is primarily related to the way that energy spreads out, but matter is indirectly involved in entropy changes because energy dispersal can cause matter to enter a more disordered state. For example, compressed gas molecules will naturally spread out into greater disorder as a result of random molecular motion induced by thermal energy. It is difficult to quantify degrees of energy and matter dispersal, so introductory discussions of entropy focus on how entropy changes when a particular event or reaction takes place. A negative change in entropy indicates that the disorder of an isolated system has decreased. For example, the reaction by which liquid water freezes into ice represents an isolated decrease in entropy because liquid particles are more disordered than solid particles.

Related Articles

5 Space Science Kits That Are Out of This World
How to Calculate the Amount of Heat Transferred
The Difference Between Hot & Cold Molecules
Science Project: The Effects of Temperature on Liquids
What is an Endergonic Reaction?
How to Prepare Supersaturated Salt Water Solutions
Why Does Heating Interfere With the Activity of an...
What Is Thermodynamics?
What Is Gibbs Free Energy?
Why Does Ice Have a Lower Heat Capacity Than Liquid...
How to Convert Nanometers to Joules
How to Calculate Heat of Sublimation
What Happens When Ice Is Added to Hot Water and How...
Examples of Applied Science
Two Examples of Endothermic Processes That Are Spontaneous
Why Does Sugar Affect the Freezing Point of Water?
Thermal Dynamics Experiments for Kids
Does the Mass of the Reactants Affect the Rate of Chemical...
Explaining Why Condensation Is Exothermic
What Are Causes of Chemical Reactions?