Few examples of pure substances include steel, iron, gold, diamond, water, copper, and many more. Air is also often considered as a pure substance.
The mixture is a material composed of two or more different substances which are combined physically. A mixture can be usually separated back to its original components. Impure substances are also referred to as mixtures.
Mixtures are unlike chemical compounds because:
The substances of a mixture can be separated using some physical methods like filtration, distillation.
Mixtures always have variable compositions, whereas compounds have a fixed and definite composition.
When mixture forms, there is only a little or no energy change.
Some examples of mixtures include:
Crude oil - Mixture of some organic compounds, mainly hydrocarbons
Air - Mixture of different gases like nitrogen, oxygen, carbon dioxide, neon, and so on
Gunpowder - Mixture of potassium nitrate, sulfur, and carbon
Ink - Mixture of colored dyes which can be separated using chromatography
Blood - Mixture of numerous abundant substances including red and white blood cells; plasma, containing glucose, water, albumin, and so on
Mineral Oils - Mixture of branched, straight chained, and cyclic heavy alkanes
Soda - Mixture of sugar, water, and added flavors.
Fewer characteristics of Mixtures include:
The mixture is an impure substance
It has no formula
Mixtures can be fixed in any ratio
Mixtures can be of either homogeneous or heterogeneous
Their constituents can be separated easily using physical methods
Mixtures are further classified into Homogeneous and Heterogeneous.
Homogeneous Mixtures are the ones that possess the same combination and properties throughout their mass. Every unit of the homogeneous mixture is likely to be every other unit.
One of the most common examples of homogeneous mixtures is sugar mixed with water. Because, if we liquefy sugar with water and blend it well, the resultant concoction is essentially the same no matter where we test it. Homogeneous mixture is composed of two or more chemical substances.
Heterogeneous Mixtures possess different compositions and properties in various parts. It means the properties won’t be uniform throughout the mixture.
For example, if we keep a little amount of sugar in a vessel, add some sand on the same, and shake the vessel twice, the concoction does not have the same configuration all throughout the jar. As the sand is heavy, there is a possibility that sand will be covered by the bottom part of the jar and whereas sugar will be occupied with the upper part. These mixtures can be visually identified and separated easily by physical means.
Some basic differences between homogeneous and heterogeneous mixtures are listed below.
Few of the points that differentiate mixtures and pure substances include:
Which are Good Examples of Homogeneous Mixtures?
Cement is one of the solid homogeneous mixtures of calcium compounds. If we mix it with sand, gravel, and water, it becomes concrete, thereby, and is one of the world's most popular construction materials.
Water itself is a liquid homogeneous mixture. All except the purest water contains dissolved minerals and gas. These are absorbed in the bath, and the liquid remains in the same phase and homogeneous.
Gas homogeneous mixtures, such as heliox and trimix, are used in SCUBA diving.
Which are Good Examples of Heterogeneous Mixtures?
A salad with cheese, lettuce, seeds, tomatoes, broccoli, and a few other vegetables is an example of a solid heterogeneous mixture.
Mud puddles are heterogeneous liquid mixtures. Dirt, leaves, and all manner of other precipitation mixes with rainwater and pools into a mixture where the elements can be easily identified.
Perfume and cologne are the well-known gaseous heterogeneous mixtures, with small droplets of fragrant substances drifting like a fog in which gas droplets are trapped in a liquid dispersion medium.
Why is Coffee a Mixture, but not a Pure Substance?
We already know that coffee is prepared with more than one substance. It contains water, caffeine, and many different chemicals from the coffee bean that produce the flavor or taste. Even though it is not a pure substance, it is a homogeneous type of mixture because it has the same composition throughout the mixture.