A mixture is a physical blend of two or more compounds. Each compound retains its own characteristics in the mixture. Scientists recognize two types of mixture: homogeneous and heterogeneous mixture. In the overview article, we’re going to explore the former.
In a homogeneous mixture, all components and particles are distributed uniformly. All of its constituents are dissolved in the same amount throughout any given sample. In fact, all solutions can be considered as a homogeneous mixture.
No matter how many different particles a homogenous mixture contains, it is almost impossible to see these particles with the naked eye or separate them using physical methods, such as a filter or centrifuge.
While the initial phase of solute and solvent may differ, the final solution always has one phase (gas, liquid, or solid). Also, the physical properties of the solution, such as its boiling or melting point, may differ from those of the individual components.
All in all, a homogenous mixture has four key characteristics:
- It has only one phase.
- Although constituents of the mixture retain their chemical property, they are not visibly separate. (However, these constituents can be seen individually at a molecular level).
- Constituents of the mixture cannot be separated using any mechanical method.
- Samples extracted from the different parts of the mixture have identical properties and composition.
How homogeneous mixtures are different from pure substances?
People often get confused between a pure substance and a homogenous mixture because they are both uniform and consist of a single phase. The difference lies in their composition.
While pure substances are usually made of one kind of particle and have a constant and fixed structure, homogeneous mixtures are made of two or more compounds of varying ratios. For example, the amount of sweetener in the soft drink can vary from one sample to another.
To better explain this phenomenon, we have gathered some of the best examples of homogeneous mixtures you encounter in your daily life.
Note: Deciding whether a mixture is homogeneous and heterogeneous depends on the way you are observing it. When you put a mixture under a microscope, you can observe its individual components. That’s why on micro- and nanoscale, almost all homogenous mixtures become heterogeneous.
Constituents: Coffee and milk
To feel less tired and increase your energy level, you make yourself a cup of coffee. You pour your favorite coffee into the mug, add milk and sugar, and stir everything together.
What you get is a uniform, brown caffeinated drink. Each sip tastes and looks the same. And once the coffee is ready, you can’t separate its ingredients (coffee, milk, and sugar) via physical methods. It’s a perfect example of a homogeneous mixture that takes the characteristics of the substance you have added the most.
Constituents: Heavy Hydrocarbons
Phase: Viscous fluid
Bitumen is a low-grade crude oil, which is made of complex, heavy hydrocarbons. In an old reservoir, it’s a thick, viscous fluid.
When bitumen is extracted from the ground, it is treated with various other chemicals to upgrade it to a better product. Nano-modified bitumen binders can be fine-tuned to exhibit excellent properties for applications in pavement engineering.
For example, carbon nanotubes (one of the most promising lightweight carbon nanomaterials with a homogeneous three-dimensional network and high porosity) can be mixed with bitumen to improve its rutting resistance, high-temperature stability, stiffness, and recovery behavior.
Constituents: Calcium, silicon, and aluminum compounds
Cement is an inorganic binder mostly used for making concrete. Nearly 4 billion tons of cement are produced every year worldwide, of which half is made in China.
Cement is made of 60-65% Lime (calcium oxide or calcium hydroxide), 17-25% Alumina (aluminum oxide), 3-8% Magnesia (magnesium oxide), 1-6% iron oxide, 1-3% sulfur trioxide, and 0.1-0.5% calcium sulphate. When these components are mixed and crushed together, they form a homogenous powder.
Constituents: Copper and tin
Bronze is an alloy of copper and tin. It can be called a homogeneous mixture because the proportions of copper and tin aren’t exactly the same in all bronze.
While bronze mostly contains copper (87-88%) and tin (12-12.5%), other materials are often added to create a range of alloys with different properties. These materials could be metals (such as aluminum, manganese, or zinc) as well as nonmetals or metalloids (such as phosphorus or arsenic).
Since bronze exhibits high ductility, stiffness, and machinability, it is widely used in bearings, springs, automobile transmission, and similar fittings. Unlike steel, bronze doesn’t generate sparks when struck against a hard surface. Thus, it is also used to make mallets, wrenches, hammers, and other durable tools to be used in explosive environments.
Constituents: Iron and carbon
Steel is a homogenous alloy made of iron and carbon. Other elements are also added in small amounts to configure its property. For example, one-tenth chromium is added to stainless steel to make it corrosion- and oxidation-resistant.
Because of its impressive tensile strength, yield strength, and low cost, steel has become one of the world’s most common alloys, with over 1.6 billion tons produced annually. It is extensively used in machines, tools, buildings, infrastructure, cars, ships, weapons, and electrical appliances.
7. Nitrous Oxide
Nitrous oxide tanks used in dentistry
Constituents: Nitrogen and Oxygen
Nitrous oxide, also known as laughing gas, is a homogeneous mixture of nitrogen and oxygen. It’s an oxide of nitrogen with the chemical formula N2O. At room temperature, the gas is colorless, non-flammable, and water-soluble. At higher temperatures, it acts as a powerful oxidizer.
Because of its anesthetic and pain-reducing effect, it is widely used in dentistry and surgery. It is also used as an oxidizer in rocket propellants and in internal combustion engines to enhance the power output. The gas provides more oxygen during combustion, allowing the engine to burn more fuel and produce more power.
According to the Grand View Research report, the global nitrous oxide market size will reach $1.47 billion by 2025. Asia Pacific market is projected to experience significant growth in the coming years.
Constituents: Water and acetic acid
Most kinds of vinegar you buy in a store are homogeneous. This versatile mixture presents a treasure trove of uses for cooking, gardening, and cleaning. It also has several medical applications.
Standard white vinegar is composed of 93-96% water and 4-7% acetic acid. Some can even contain nearly 20% acetic acid, but they are specially made for cleaning and agricultural purposes, not for human consumption.
5. Saline Solution
Constituents: Salt and water
Saline solution is a mixture of sodium chloride (salt) and water. Conventional saline contains 0.9% salt and 99.1% water, which is similar to sodium concentration in tears and blood.
Lower and higher concentrations solution are also occasionally used. Normal saline has several medical uses. For example, it is used to clear sinuses, clean wounds, treat dehydration, and helps with dry eyes.
4. Laundry Detergent
Constituents: Water softeners, surfactants, bleach, and enzymes
Phase: Liquid and solid (powder)
Laundry detergent (cleaning agent) is produced in powder and liquid form. In terms of volume, powered detergents are sold twice as much compared to liquids. However, in terms of value, they both hold equal shares of the worldwide laundry detergent market.
Most laundry detergents contain 50% water softeners (by weight), 15% surfactants, 7% bleach, 2% enzymes, and other ingredients such as soil anti-deposition agents, optical brighteners, fragrances, and corrosion inhibitors.
Each manufacturer has secret ingredients and synthetic processes to make their specific brands. Many of these ingredients are made from plants, whereas others are petroleum based. The amount of every ingredient and the way they are mixed determines the cleaning ability of the detergent.
Constituents: Crude oil and other petroleum liquids
Gasoline is used as a fuel in most spark-ignited internal combustion engines. It is made of organic compounds obtained via the fractional distillation of petroleum. Various chemicals are added to enhance its performance characteristics and improve chemical stability.
For example, oxygen-containing chemicals, such as ethanol and Methyl tert-butyl ether, are added to gasoline to improve combustion. This gives a colorless, flammable homogeneous mixture. Many petroleum manufacturers also add dyes colors to this liquid to differentiate the different grades of gasoline.
2. Blood Plasma
Constituents: Water and vital proteins
Plasma is the yellowish liquid portion of blood that is uniform in composition throughout. About 55% of the body’s total blood volume is plasma, and the remaining 45% are white blood cells, red blood cells, and platelets.
Plasma is mostly made of water (92%) and vital proteins (7%) such as serum albumins, globulins, and fibrinogen. A small fraction (1%) of plasma contains mineral salts, fats, sugar, vitamins, and hormones. It carries electrolytes (such as potassium and sodium) to muscles and helps maintain the blood pressure and proper pH balance in the body.
Constituents: Water and vital proteins
Air is a homogeneous mixture of gaseous substances. Since each layer of the Earth’s atmosphere has a different density, the amount of different substances present in the air varies.
The air in the troposphere (the lowest layer where all weather conditions take place) contains nearly 78% nitrogen, 21% oxygen, 0.9% argon, 0.04% carbon dioxide, and tiny amounts of other gases.
The troposphere contains 99% of the water vapor in the atmosphere. It regulates air temperature by absorbing solar energy and thermal radiation from the ground.