What Are The Chemical And Physical Changes?

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Chemical and physical changes are an essential part of our day-to-day lives. Every time we cook, clean, drive a car, or turn on the lights, we experience some form of chemical or physical change.

A chemical change is a process during which new substances with different characteristics than the original ones are produced. During a chemical change, atoms rearrange themselves to create new compounds that can be completely different from what was there before.

On the other hand, physical changes do not involve the creation of new substances; instead, they only alter the appearance or phase of matter. They include processes such as melting, freezing, cutting objects into smaller pieces, and dissolving solids in liquids.

“Chemical and physical changes are fundamental concepts in science that help us understand how the world works.”

Understanding the differences between chemical and physical changes has practical applications in fields ranging from cooking and cleaning to medicine and engineering. Knowing what kind of change is happening in a particular situation can help us predict outcomes, prevent accidents, and develop better products to meet our needs.

In this blog post, we will explore the basics of chemical and physical changes, their properties, examples, and applications. You will learn about the fundamental principles behind chemical reactions and physical transformations, and how they influence our daily lives. So let’s delve deeper into the fascinating world of chemical and physical changes!

The Definition of Chemical Changes


Chemical changes refer to the process that occurs when one or more substances are transformed into new substances with different chemical properties. This means that there is a rearrangement of atoms, resulting in the formation of new bonds between them and forming entirely new molecules.

One vital characteristic of a chemical change is that it involves a modification that cannot be simply undone by physical means: heat, light, pressure, and electricity together with other modifying factors can’t alter the original substances’ chemical makeup.


During chemical reactions, reactants interact to form products with unique characteristics. Here are some examples of chemical changes:

  • Burning paper: When burning paper, the cellulose fibers present inside reacts with oxygen from the air, releasing smoke (carbon dioxide and water vapor) wherein ash contains only carbon and minerals remaining
  • Rusting iron: Rusting occurs when iron metal comes into contact with moisture and corrosion starts taking place on its surface leading to the production of reddish-brown iron oxide (rust).
  • Digestion: Digestion refers to an essential chemical reaction that turns our food into materials the body needs for energy. In this scenario, your digestive system breaks down food using acid and enzymes so you can extract nutrients and energy from what you eat.
“In everyday life, several processes that we encounter involve chemical changes ranging from cooking food to driving a car.” – Cara Batema, Live Science Contributor

Chemical changes reveal essential phenomena that occur in our day-to-day lives, despite being invisible to us. These techniques have allowed us to learn about how materials transform over time and enhance our understanding of the natural world around us.

The Definition of Physical Changes

When talking about the changes that can occur to matter, they can be divided into two categories: chemical and physical changes. While both types involve a transformation in the composition of material substances, there are a few key differences between them.

A physical change refers to any alteration to a substance where its fundamental nature does not change. That means you end up with the same type of element or compound as you started with, but it may have altered in appearance or undergone some structural modifications. In other words, this process is primarily concerned with physical properties rather than the chemical ones. So, what are some examples of these types of alterations?


Physical changes refer to any transformation of matter that affects one or more physical properties without altering the basic nature of the underlying substance. They’re reversible processes that don’t cause new molecules to form. Their defining property is their ability to change appearances while retaining molecular identity and structure.

The changes that happen during these transformations could include several different things such as the shape, size, temperature, mass, volume or state of an object. Physical changes are often easy to identify because they tend to produce visible effects on an object’s physical characteristics


One example of a physical change is melting ice. When solid water warms up sufficiently, it will transition from its solid state (ice) to its liquid state (water). This is due to the absorption of heat energy which makes the water molecules move around faster and therefore break apart their crystalline structure. Conversely, if we were to take that same liquid water and cool it down enough, eventually it would return back to being a solid iceberg. That same water molecule has gone back and forth between states, only altering its physical structure each time.

Another example of a physical change is friction between two objects that results in the superficial change of one or both. This could involve chipping paint, scratching surfaces, or cracking foundations. While this doesn’t necessarily alter the fundamental composition of either object, it does affect their visual appearance and structural integrity.

Changes in State

The most common type of physical change is an alteration to matter’s state -for instance, turning a solid into a liquid, or gas into a plasma- here are some examples:

  • Melting ice
  • Boiling water into steam
  • Evaporating alcohol
  • Condensing water vapor from the air onto a cold surface
  • Sublimating dry ice (solid carbon dioxide) to become gaseous CO2 without going through a liquid phase first
  • Freezing liquids like water or oils and transforming them back again as they thaw
“A physical change involves altering the appearance or properties of a substance while retaining its underlying structure.” -Explorable.com

Physical changes represent alterations to certain physical qualities of matter without changing the way molecules bond together chemically. These processes happen all around us every day: baking bread, boiling eggs, cutting wires, crushing cans, smashing windows, melting plastic toys with magnifying glasses, and inflating balloons or beach balls.

The Differences Between Chemical and Physical Changes

Many things in the world around us undergo changes. Some of these changes are a result of chemical processes, while others are due to physical causes. It is important to understand the differences between these two types of changes, as they can lead to very different outcomes.

Chemical Changes

A chemical change occurs when one substance reacts with another substance and transforms into something new. In other words, chemical reactions rearrange the atoms to form new molecules. During chemical changes, there are often noticeable changes such as heat or light being produced, color changes, gas production, or an odor emanating from the substance.

An example of a chemical reaction is the rusting of iron. When exposed to oxygen and moisture, iron will begin to corrode, forming reddish-brown rust. The formation of rust is a chemical process that cannot be reversed simply by wiping away the discoloration.

Physical Changes

A physical change involves altering the form, texture, or state of matter but not creating something entirely new. For instance, when water freezes, it becomes solid ice. While this may look quite different from liquid water, it is still comprised of the same combination of hydrogen and oxygen atoms.

Other examples of physical changes include melting, boiling, evaporating, and crushing. These changes affect the physical properties of the substance but do not alter its chemical makeup.

Distinguishing Between the Two

One way to differentiate between a chemical and physical change is by the ability to reverse the transformation. Physical changes have the potential to be undone, whereas chemical changes typically cannot be easily reversible. For example, if you melt an ice cube, you can freeze the water again back to its original state, whereas if you burn a piece of paper, it is not possible to convert it back to its original form.

Another way to differentiate between chemical and physical changes is the type of testing results that can be used. Physical changes do not cause any alterations in the molecular structure of a substance, whereas chemical changes lead to new molecule formation and conversion of chemical energy to heat or light.

Energy Changes

During a chemical reaction, there is always an exchange of energy. This may be in the form of heat energy, light energy or even sound energy depending on the nature of the reaction. In some cases, a chemical reaction requires a gain of energy from another source before being able to proceed.

An example of this is photosynthesis where plants require sunlight as their source of energy in order to transform carbon dioxide and water into glucose (sugar) and oxygen gas.

“Chemical reactions are essentially exchanges of energy.”

The concept of energy change during chemical and physical processes is important in many areas, including medicine, manufacturing, and environmental science. Understanding these differences can provide valuable insight into making informed decisions about how we interact with our world.

Knowing the difference between chemical and physical changes enables us to appreciate the reality that substances undergo transformations through different mechanisms. Physical changes happen when elements alter states without changing what they chemically are. Conversely, chemical changes result in newly formed molecules leading to modified properties such as differences in odor and color, among others. Differentiating between the two allows scientists and individuals to make wise choices when working with matter.

Examples of Chemical Changes


Combustion is a type of chemical change that involves the production of energy by burning substances with oxygen. This process results in a release of heat and light, as well as the formation of new compounds.

An example of combustion is burning wood in a campfire. The heat and light produced by the burning wood are the result of the chemical reaction between the wood and oxygen in the air. Another example is the combustion of gasoline in a car engine, which powers the vehicle through a series of explosions in the cylinders.

“Combustion is an important concept in chemistry because it involves the transformation of one substance into another, often with the production of energy.” -Ralph Pearson


Rusting is a slow form of oxidation, a chemical change that occurs when iron or other metals react with oxygen in the presence of moisture. Rusting is essentially the decomposition of metal due to a chemical reaction with its environment.

For example, when exposed to air and water, a piece of steel will begin to rust over time. This is a chemical change as the iron in the steel reacts with the oxygen and water, ultimately resulting in the formation of iron oxide or rust.

“The process of rusting illustrates how even seemingly stable materials can undergo significant chemical changes over time.” -James Watson


Decomposition happens when a compound breaks down into simpler substances due to a chemical reaction. This kind of chemical change also leads to the formation of new products.

A good example of this is the breakdown of food in our digestive system into smaller molecules for absorption by the body. Chemical changes occur as enzymes in the digestive system hydrolyze complex molecules like carbohydrates, proteins, and fats into simpler compounds such as glucose, amino acids, and fatty acids.

“Decomposition is a crucial process in nature that allows organic matter to be recycled within ecosystems.” -Albert Einstein

Chemical changes are those that involve the breaking of chemical bonds between atoms or the formation of new ones. These processes may result in the production of energy, light, heat, or new substances altogether, with combustion, rusting, and decomposition being some common examples. Understanding these phenomena can help us appreciate how chemistry impacts our daily lives and the natural world around us.

Examples of Physical Changes

Physical changes are those that do not affect the composition of matter. They simply alter the state or appearance of a substance. There is no new substance formed during a physical change, and the original properties remain intact.

Melting Ice

When ice melts, it undergoes a physical change because there is no alteration in its chemical structure. The heat from the surroundings causes the solid molecules to gain energy, vibrate faster, and overcome their intermolecular bonds. This transition results in a loss of shape, as ice transforms into liquid water. During this process, the volume remains the same. Solid water has a set shape, whereas liquid takes on the form of its container. Once the temperature decreases below 0°C/32°F, water will freeze and become a solid again.

Boiling Water

The boiling point of water is about 100°C/212°F at sea-level pressure. When water is heated to that degree, it begins to evaporate. The heat source facilitates the transition from liquid to gas phase as more energy increases the motion of the water particles which helps them escape the surface. Boiled water is still water, but it’s now in gaseous form. It can’t be seen by the naked eye until you see steam, which forms due to condensation when the vapor meets cooler air. As soon as the steam disappears, the water cycle continues, producing tiny droplets high in the atmosphere, where they eventually combine to produce clouds and precipitation.

Bending a Piece of Metal

If you take a piece of metal, say aluminum foil, and crumple it up, or bend it, it looks different than before. However, it doesn’t necessarily change chemically, so it’s considered a physical change. That’s because the material remains aluminum, and no new substances are produced during this transformation. Bending or crumpling applies pressure to metal which creates an uneven distribution of molecules, causing it to stick in an altered shape.

Physical changes can take place when energy is either absorbed or released from matter. In fact, most of our daily routine and experiences involve numerous physical transformations that we might not even be aware of, but understanding these basic examples will lead us through further understanding how the world around us operates.

Real Life Applications of Chemical and Physical Changes

Chemical Changes in Cooking

Cooking is one of the classic examples of chemical changes in everyday life. In cooking, we use heat to create a reaction that causes chemical changes in the ingredients used. The most basic example can be found when we cook eggs: from clear liquid raw eggs, to opaque white and yellow solid. This change happens because of the high temperature.

The browning effect in baked goods or meat known as “Maillard Reaction,” that occurs between amino acids and reducing sugars during heating at high temperatures has become prevalent in our daily lives too. Have you ever noticed the beautiful brown color of crusty bread? Or biscuits smelling divine while baking? These are all due to Maillard reactions, where sugars react with proteins produce caramelization.

Besides this, fermentation has been another way chemical changes take place. Techniques such as leavening of doughs for bread making require yeast converts sugar into carbon dioxide that helps trapped air bubbles which expand and make the bread rise. Alcoholic drinks also undergo fermentation by yeasts on sugar conversion, resulting in their intoxicating properties.

Physical Changes in Materials Science

Materials science is a branch of chemistry that studies the structure, composition, properties, and behavior of matter. In materials science, understanding physical changes is crucial as it results in new and improved products.

An example of a physical change is the glass transition (Tg). It is the reversible transformation of certain amorphous solids from a hard and relatively brittle state into a more viscous or rubbery state. This change allows for further processing but without increasing thermal energy significantly. For example, polymers go through glass transitions when they melt; this gives them stretchable and ductile properties required in various products like plastic bags, toys or sportswear.

Another example of physical changes in materials science is “Shape Memory Polymers.” These are polymers capable of restoring their original shape after being stretched or creased. This change happens because of the alteration in molecular chains caused by high temperature or ultraviolet rays acting in the same manner as heat does to add energy and rearrange the macromolecular structure. This technology has allowed us to make things such as artificial muscle implants – a prosthetic that can replicate real muscles used for movement in our body.

Chemical and Physical Changes in the Environment

Natural phenomena like weathering, erosion, evaporation, biological decay, etc., are examples of chemical and physical transformations happening around us every day.

One of the most important applications of chemistry and physics is related to air pollution and greenhouse gases, causing many environmental problems. Emission from motor vehicles and factories produces carbon dioxide, among other gases that cause global warming – an example of a pure chemical reaction. Moreover, natural processes affecting the environment can also be seen through chemical reactions: rust formation with iron exposed to Oxygen and water makes bridges degrade over time; acid rain formed when industrial pollutants mix up with rainfall corrodes buildings and plants..

“Green Chemistry” gives people knowledge about safe and sustainable methods to lessen the negative impacts brought upon by chemicals used in manufacturing. The use of eco-friendly alternatives that do not harm the environment has become a necessity to reduce the hazards faced today.
  • Examples of Prevention Techniques:
    • Reusing products
    • Closer monitoring of emissions coming out of factories
    • New ways of production that do not involve toxic levels of waste material

Scientific studies help us understand chemical and physical changes happening around us. It is vital to analyze the impacts of these transformations on our planet as well as its inhabitants.

In conclusion, physical and chemical changes occur in many forms and have various applications that benefit human society; they can provide entertainment such as cooking or construction materials for making buildings damage-resistant or even eco-friendly alternatives that reduce environmental pollutants. Understanding these applications helps us strive towards a better quality of life and condition for not only ourselves but also other organisms living on Earth.

Frequently Asked Questions

What is a chemical change?

A chemical change is a process in which the composition of a substance is altered, resulting in the formation of a new substance with different properties. Chemical changes involve the breaking and formation of chemical bonds, and often produce energy in the form of heat or light.

What is a physical change?

A physical change is a process in which the physical properties of a substance are altered, but the composition of the substance remains the same. Physical changes can involve changes in state, such as melting or freezing, or changes in shape or size.

What are some examples of chemical changes?

Examples of chemical changes include combustion, rusting, and cooking. Combustion involves the burning of a substance, which produces heat and light. Rusting is the oxidation of iron, resulting in the formation of a new substance with different properties. Cooking involves the chemical transformation of food, resulting in new flavors and textures.

What are some examples of physical changes?

Examples of physical changes include melting ice, cutting paper, and dissolving sugar in water. Melting ice involves a change in state from solid to liquid, but the composition of water remains the same. Cutting paper involves a change in shape, but the paper is still made of the same material. Dissolving sugar in water involves a change in size and shape, but the sugar molecules remain the same.

How can you differentiate between chemical and physical changes?

You can differentiate between chemical and physical changes by observing whether the composition of the substance has changed. If the substance has formed a new substance with different properties, it is a chemical change. If the substance has only undergone a change in physical properties, such as a change in state or shape, it is a physical change. Other indicators of a chemical change include the production of heat or light, or the release of gas or odor.

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