Properties of Pure Substances

Introduction

Pure substances are referred to objects that are made up of only one kind of particle. Pure substances are fixed structures in nature. The term pure substances are quite understandable and have a simple meaning. The classification of pure substances is as follows: compounds and elements. Only one single type of atom constitutes the body of a pure substance. The sole truth of pure substance is that it cannot be broken down. It also cannot be transformed, even if external means like chemical or physical means are applied. Metalloids, non-metals, or metals constitute the category of elements.  

Compounds are also considered to be pure substances. It is so because; more than one pure substance is combined in a fixed ratio to give birth to a certain compound. These compounds can be broken down and still be considered pure substances as they were made with pure substances in the first place. From a young age, we were taught that matter is divided into gases, liquids, and solids. But growing up, as our knowledge expands; we get to know that matter further gets divided into mixtures and pure substances.

Properties of pure substances

Pure substances have several characteristics and properties. They are as follows:

1. Temperature – Temperature is the first property of pure substances Kelvin and Celsius are the two most commonly used units for temperature. For converting Celsius into Kelvin, we need to add 273.15. For Example – if the temperature of a substance is 50 Celsius, then its temperature in Kelvin will be 50+273.15= 323.15. The lowest temperature ever achieved is 0 Kelvin.
2. Pressure – Force per unit area is called pressure. The formula for pressure is as follows:

                                                     P=FA.  

1. Volume and mass – People often confuse between volume and mass. But in reality, there are not many similarities between these two. It is an intensive property. There is a special term: specific volume (v). The value we get after dividing total volume by total mass is called specific volume, v=Vm. The inverse of specific volume is density.  

Characteristics of pure substances

The characteristics of pure substances are as follows:

1. Pure substances are made of a single type of molecule or atom. It is so because they are mostly homogeneous.
2. Pure substances are uniform and constant.
3. Pure substances always have specific or fixed melting points and boiling points.
4. Predictable subjects are formed when pure substances come under chemical reactions.

Examples of pure substances

Pure substances have several examples. In the case of elements, there is gold, oxygen, chlorine, copper, diamond, etc. A few of the compounds also fall under pure substances. They are water, baking soda, crystals, etc.

Pure Substances and Mixture – Differentiation

There are several differences between pure substances and mixtures. They are as follows:

1. New products cannot be created by separating a pure substance, while mixtures can be separated using different methods.
2. Pure substances have a fixed and specific chemical and physical property, while mixtures have variable properties.
3. Pure substances comprise a single element, while mixtures are made up of two or more elements.

Important terms of a pure substance

Important terms when dealing with pure substances include:

• Vaporization is the point where a liquid changes into a vapor phase
• Condensation, which is the point that a vapor changes into a liquid phase (and is the same point as for vaporization)
• Melting point is the point where a solid turns into a liquid
• Freezing point is the point when a liquid turns into a solid
• Sublimation is the point that a solid turns directly into a vapor
• Desublimation means the point that a vapor turns directly into a solid (unusual, but it happens)
• A critical point occurs where the saturated liquid and saturated vapor curves meet and become the same.
• The triple point is the point where the gas, liquid, and solid phases exist at the same temperature.

Conclusion

The topic of properties of pure substances teaches us several things. Several terms are new to us and might be helpful for us in the future. Pure substances and mixtures make our whole world. It forms an integral part of both chemical and physical science. Most of the details are provided in the topic above. The FAQ section deal with a few of the probable questions and answers. Hope it is helpful to every student out there.