The thermodynamics system simply refers to a specific quantity of matter or definite region in space. There are certain features in every thermodynamic system that describes its conditions. Such features are known as properties. These properties are microscopic in nature (you can’t usually see them with naked eye). Properties are also known for being the point functions like property has a specific value in each state. Many of these properties also depend on the concerned system’s mass, some of them are independent of mass. Thermodynamics properties can be defined in two groups.
- Intensive properties: These are the ones that are physical properties and do not depend on the amount of matter or substance. These are independent of the amount of matter.
- Extensive properties: These are the ones that depend on the amount of matter or substance. Totally dependent on the quantity or amount of matter.
We must recall these words from our chemistry class but not everyone can still differentiate these properties. For those of you who can differentiate the properties still, well done. However, for those of us who don’t quite remember, here’s a little explanation of each property.
What are Intensive Properties
These properties are limited to the physical ones and they don’t on the size or amount of matter. These properties wouldn’t change if we increase or decrease the size of the matter. You may understand this concept better if we use some examples.
Melting point & boiling point
This property is strictly intensive property. Irrespective of the size or amount of the matter, the value obtained for melting or boiling point of respective substance will stay the same. Nice example would be the boiling point of water, so if water boils at 100 Degree Centigrade, it will boil at the same temperature even if we increase the temperature of 100 ml of water.
Another one of the intensive properties. The density is mass per unit volume of the substance. So irrespective of the amount we have, we only measure the mass per unit volume. This applies to the homogenous systems only.
The color is also regarded as intensive property because it remains the same irrespective of the amount.
Temperature is well regarded as intensive property because the temperature at one point of substance will be same as the other point.
These properties do not depend on the size or amount of substance so they can be really useful in identification of substances.
What are Extensive Properties
These are mainly only the physical properties of the matter that totally depend on the amount. This literally means that these properties can be changed with the size or amount of the matter being altered. Still, these properties can be observed easily without disturbing any chemical composition of the matter.
Here is the example:
The volume of substance varies for different amounts which make up the mass, energy and particle number.
Physical and Chemical Changes to the Matter
Changes to the matter are mainly of two types; physical change and chemical change.
You can think of it as simply as that physical changes can’t cause any substance to change completely into a different substance while a chemical change can cause any substance to change in to a new substance chemically. For example, if you have to involve physical change, then the fruit of each shape will mix with other different pieces of fruit. However, no chemical of the fruits would change while blending the fruits (the vitamins and water content of the fruits remain same even after the physical shape of the fruit would change in the smoothie), so we would know that there are no chemical changes in this process, only physical.
When you tear, grind, shatter, cut or mix you are just making further physical changes in the subject and they change the form right in front of you but the material composition remains very same. Like mixing salt and pepper would create a completely new substance while the chemical make up of either substance wouldn’t change. There are other changes like phase changes which occur when different substances go through different phases like being frozen, boiled, melted, deposited, sublimated or condensed. These phase changes are also physical changes as they in no way change the nature of the substance.
These changes are also known as chemical reactions. The reaction is triggered by ingredients known as the reactants, but the end results are known as products. The change from reactants to products is mainly signified with an arrow:
Reactants → Products
Gas bubbles are formed as a result of a chemical change (excluding the boiling, that is a physical change). Chemical change may also be indicated by the formation of a precipitate like formation of cloudy material when the dissolved substances are added.
Burning, rotting, cooking and rusting are all kind of chemical changes as they form new substances that form completely new chemical compounds. For instance, when wood is burned it becomes ash and releases carbon dioxide and water. Iron also forms a mixture of many hydrated iron oxides and hydroxides when it is exposed to water. Yeast also forms alcohol and sugar through the process of fermentation.
The color changes and odor releases also are a sign of chemical change, like, the color of chromium element is indicated by its oxidation state, as a single chromium compound will only change color if there is any process of reduction or oxidation reaction. The proteins in the egg white are changed with the heat while cooking them and the shape also changes, changing the molecular state of the proteins in egg while and converting from translucent to opaque.
You can figure out a chemical or physical change by performing chemical analyses like mass spectroscopy on the substance to figure out its composition after and before the reaction.
The conclusion is pretty simple as the intensive properties are independent of the amount of matter and extensive properties are dependent on amount of matter.