Compound and mixture have relatively simple dictionary meanings in English, but when studied as terms in chemistry, they become more complicated.
Key Takeaways
- Compounds are substances made up of two or more elements that are chemically combined, while mixtures are made up of two or more physically connected substances.
- Compounds have a fixed ratio of elements and cannot be separated physically, while mixtures can be separated by physical methods such as filtration or distillation.
- Compounds have properties that differ from their constituent elements’ properties, while mixtures retain the properties of their components.
Compound vs Mixture
Compound is a substance that is made up of two or more different types of atoms chemically bonded together in fixed ratios and have a specific chemical formula. Mixture is a combination of two or more substances that are physically combined but not chemically bonded and can be either homogeneous.
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Since the elements are chemically bound in a compound, they cannot be physically removed. Unlike compounds, the different substances in a mixture can be separated using physical methods.
Comparison Table
| Parameter of Comparison | Compound | Mixture |
|---|---|---|
| Definition | Two or more elements are chemically bound to form a compound, | Two or more substances are combined physically to form a mixture |
| Types | Homogenous | Homogenous and Heterogeneous |
| Separation | Chemical means | Physical means |
| Proportion | Definite and fixed | Varies |
| Result | The new substance is created | No new substance is created |
What is a Compound?
Chemically binding two or more chemical elements together create a compound. The atoms that make up these elements are bound together using their electrons, and by binding them together, a new substance, a compound, is formed.
The proportion in which the elements are bound together is definite and fixed. The formula for each compound is written according to the elements that form it and their proportion.
The formula for water is H2O. This shows that water is a compound comprising two hydrogen atoms and one oxygen atom.
Atoms bond together in different ways, and the bonds that create compounds are categorized accordingly.
In cases where one atom gives an electron and the other gains one, an ionic bond is formed. The electric charge of the atoms changes upon losing and gaining electrons, and they become ions.
When we look at the example of sodium and chlorine, an electron from sodium is transferred to chlorine. Sodium becomes a cation because it becomes positive, and chlorine becomes an anion because it becomes harmful.
This is an ionic bond, and the formula for the compound this creates is NaCL which, in layman’s terms, is salt. Covalent bonds are the most commonly occurring of all bonds.
Rather than transferring an electron from one atom to another, electrons are shared between the two atoms in covalent bonds.
These two electrons create another orbit surrounding both atoms, binding them together into a molecule. Unlike ionic bonds created due to the attraction between opposing charges, covalent bonds are formed between atoms with similar electronegativity.
An example of a covalent bond is carbon monoxide, formed by bonding one carbon atom with one oxygen atom. Covalent bonds are formed with negatively charged atoms, but metallic bonds are formed between positively charged atoms.
This type of bond is formed between metal atoms.
Here the free electrons in both atoms are shared in lattice form without either one losing or gaining electrons. Platinum is an example of a metallic bond.
What is a Mixture?
In a mixture, two substances are combined physically. However, the chemical composition of each substance remains the same.
Therefore they can be separated using physical means. Unlike a compound, the proportion of the substances in the mixture can vary and need not be definite.
It is important to note that while the chemical composition does not change, the substance’s physical properties in the mixture will change when they are brought together.
No new substance is formed. Mixtures can be classified into two types – homogenous and heterogeneous. When a mixture has a uniform composition, it is a homogenous mixture.
Separating its components isn’t easy as usually one is a solute and the other is a solvent.
Even in cases where there are multiple components, like the air around us, which contains many gases, there are solutes like oxygen and carbon dioxide balanced with a solvent like nitrogen, making it a homogenous mixture.
A normal example would be a saline solution, just a mixture of water and salt. On the other hand, a heterogeneous mixture lacks uniformity.
The substances’ particles can be differentiated, and separating them is easy.
For example, if sand and stones are mixed, separating the stones from the sand would not be difficult. Besides this simple classification, mixtures can also be categorized based on the size of the particles they contain. In this manner, mixtures can be divided into solutions, suspensions, and colloids.
Solutions are homogenous mixtures. The size of the particles is minuscule, and once mixed, they cannot be viewed separately.
Moreover, the solute will completely dissolve in the solvent. The mixture of salt and water would fall into this category.
When a homogenous mixture has particles that are of medium size, the mixture is a colloid.
Here the particles can be viewed separately even after mixing, but they can be separated by filtering. Fog and jelly are examples of a colloidal mixture.
Lastly, we have suspension mixtures that are heterogeneous. The particles in these mixtures are large and not evenly distributed.
Suspension mixtures are further divided into three.
In a solid-solid mix, solids are mixed and can be easily separated by sifting. A classic example of a solid-solid mix is soil.
Next come solid-fluid mixtures, which contain solids mixed with liquids or gases. Even after being mixed, the ingredients will separate.
The solid particles will gradually sink to the bottom if the solids are heavier than the liquid or gas. They will rise and float on top of the mixture if they are lighter.
Therefore when dust mixes with the air, it is a solid-fluid mixture as dust is heavier than air. These mixtures can usually be separated through filtration.
The final category of suspension mixtures is fluid-fluid mixtures. Here even though liquids or gases are mixed with other liquids or gases, one will be heavier than the other, and so it can be viewed separately.
If oil and water are mixed, globules of oil will remain suspended in the water without dissolving.
Main Differences Between Compound and Mixture
- A compound is formed when two or more elements are chemically bound together.
- Mixtures are formed when two substances are combined physically.
- Compounds have elements that are combined in definite proportions.
- The proportion of the substances in a mixture can vary.
- The elements of a compound are chemically bound and cannot be separated by physical means.
- Since the substances in a mixture do not face any alteration in their chemical composition, they can be separated using physical means like filtration and sifting.
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
