In your science class, friend may have heard of chemical and physical changes. Yet do girlfriend know exactly how to call the difference between the two? The price lies in even if it is or not a change to a substance outcomes in that is molecules being rearranged.

In this article, we will define chemical and also physical and changes. Climate we"ll take it a watch at details chemical readjust examples and physical readjust examples to better understand their differences and also similarities.

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So let"s obtain started!


When ice cream melts (and goes indigenous a solid to a liquid), it undergoes a physics change.

Physical adjust Definition

First, let"s talk around physical changes in chemistry. A physical readjust occurs when a substance or object changes its appearance, phase, or is offered in a mixture. More importantly, a physical adjust does not change the molecular structure of a substance. And also you can reverse a physical change to recover every one of the initial matter, even if that doesn"t look precisely the same. In other words, in physics changes, the molecules from before and also after the readjust stay the same!

What is an example of a physical change? Things choose cutting a item of record in half, freezing water into ice or bending few of your mom"s favorite silverware (don"t perform that!) space all physical changes. That"s since physical alters only impact a substance"s physics properties, not the composition of their molecules.

Still no sure about what constitutes a physics change? Don"t worry: we"ll dig into an ext physical change examples in just a minute.


When logs burn, they undergo a chemistry change.

Chemical readjust Definition

In contrast, a chemical adjust takes ar when the initial substance"s of molecules are taken apart and put ago together into brand-new combinations that are different from the initial combinations. Furthermore, the original issue cannot be recovered. And unlike physical changes, these transforms usually usage a lot more energy, such as heat and also light, because the molecular bonds should be broken in order come rearrange them.

What is an instance of a chemistry change, then? some chemical adjust examples include a piece of paper burning, a nail rusting, or baking a cake. Like physical changes, it"s pretty clear that the way these things start and also end are fairly different: a shining nail turns orange v rust, and also wet dough i do not care a delicious dessert. The factors these are chemical transforms is that the readjust happens ~ above a molecule level. Put an additional way, the object you start with and also the object you end with are completely different substances.

So, let"s look at some an ext examples of physical and also chemical alters to much better understand the differences and also similarities in between the two.


When this mallet access time the egg, the egg will undergo a (very messy) physics change. (P.S: Don"t shot this in ~ home!)

Physical adjust Examples

Earlier us talked about some examples of physical and chemical changes. But sometimes informing a physical change from a chemical change can it is in hard. This is especially true once physical transforms require or expend energy. The crucial thing come remember is that in a physics change, the molecules remain the same.

Let"s look in ~ three various physical adjust examples to far better understand this idea.

Example 1: phase Changes

Phase alters involve changes in size, volume, and density. For instance, once you rotate water into ice or vapor, this is called a phase change. This is since water has 3 phases: solid (ice), liquid (water), and gas (vapor or steam).

It might seem like some of the water molecules are lost during each step change: the ice cream cube it s okay smaller, and steam seems to disappear right into the air. However, in each of these 3 stages, the water molecules stay the same. And if you were to cool down the vapor, it would certainly reform into water. Cool it under enough, and also it would turn earlier into ice. There would be the same amount the hydrogen and oxygen atom in the ice cube together there to be in the steam, and these atom will continue to be in the same molecular shape in every stages.

Let"s take it a closer look at what"s continue on a molecule level. Vapor is consisted of of H20 similar to the ice cube. The only difference in between vapor and ice is that the individual molecules have spread personally in vapor as result of the applications of heat. Meanwhile, in ice, the molecules team closer together due to the fact that of the absence of heat. Though this phase transforms require power to be expelled (exothermic reactions) or applied (endothermic reactions), the variety of atoms and also the shape of the molecules in the substance remains the same. That"s what renders it a physics change!

Example 2: transforms in Size and Shape


Like we stated earlier, physical changes are all about whether molecules remain the very same or not. When an object undergoes a physics change, it can come to be a different size and also shape as lengthy as the composition continues to be the same.

Here"s what we mean: if you have ever before dropped a piece of glass on the floor, you know that it will break apart, exploding right into a million pieces. If friend really want to, as soon as you brushed up all the glass up into your dustpan, you could probably fit it all back together (even despite it would take a most time and patience). This is also a physical reaction since the glass continues to be glass. When it shatters, the glass alters size and also shape, but its molecule don"t change.

This is a physical change that only entails a change in size and also shape. While energy helped break the glass into pieces, no energy was provided to rearrange the molecules.

Example 3: mixture & Solutions

Imagine you are on a day out at the beach. The sun is shining, the sand is warm, and also the seagulls space trying come steal people"s lunches. After playing in the waves because that a bit, you decision to do a sandcastle. Girlfriend fill your bucket up v sand and plop it upside down. The sand come out yet it doesn"t pole together. Girlfriend forgot to add water! You try again, this time with water and voila, you"ve created your first tower choose a understand sandcastle architect.

But why didn"t the sand stick together the an initial time? It has to do through a physical property referred to as surface tension. Surface tension describes how solid the link is in between a substance"s molecules. Water has a strong surface tension, so adding it to the sand create a strong enough bond because that the sand come cling together rather of fallout’s apart.

What renders this various from a chemistry reaction is the the sand and also the water, though mixed together, execute not change their molecular structure. The water remains water and the sand stays sand. And if you to be to measure the water the will eventually evaporate once the sandcastle dries, friend will discover that the amount of evaporated water is equal to the amount of liquid water you added to the sand originally.

This is referred to as a mixture due to the fact that both substances (the sand and also the water) retain their own physical properties.

The exact same is true if you add salt or sugar to water. The seems like the salt and also sugar dissolve and type new molecules. Yet if you were to wait because that the water to evaporate, you would discover that the salt or street molecules obtain left behind in the glass. This is dubbed a solution.

Solutions differ from mixtures in the they are homogenous. A single drop of saltwater would have actually the same number of salt molecules (NaCl) every water molecules (H2O) as an additional drop taken native the same solution. In a mixture, you might have more sand than water in two different handfuls, also if they were taken from the same bucket.

These physical adjust examples should help you acknowledge the difference between a physical and chemical change. Especially when you compare them to the chemical adjust examples below.


Dough turning into bread is a tasty instance of a chemical change.

Chemical change Examples

Both physical and also chemical changes result in one thing transforming into another. even if it is it"s a glass breaking or burn a item of paper, the initial item becomes something different.

So how can you phone call the difference in between a physical and a chemistry change? It every comes under to--you guessed it!--the molecules. In a physics change, the molecule stay specifically the very same throughout the transformation. In a chemistry change, however, it"s the molecules themselves the transform!

Here space three examples of chemical changes to help you point out the difference!

Example 1: Combustion

Combustion is a chemical reaction between substances, usually consisting of oxygen, that creates heat and also light. The power released by the reaction (in the form of heat and also light) is led to by the breaking of molecule bonds. As a result, the original substances transform into entirely different substances since of the rearrangement of molecules, which is an instance of a chemical change!

For instance, if friend mix oxygen (O2) v a form of hydrocarbon referred to as methane (CH4), the molecule bonds that both substances room broken, which creates the heat and also light. The bonds climate reform to produce two various molecules: carbon dioxide (CO2) and also water (H2O).

Combustion reactions can take place at various rates, too. An example of a slow-moving reaction is a complement burning. A quick reaction would be gunpowder exploding. The amount of energy released in any combustion reaction relies on exactly how much power is necessary to break the molecular bonds. The harder the is to break the bonds, the more energy is released overall. But regardless of even if it is the reaction is quick or slow, combustion is a chemical change.

Example 2: Decomposition

Decomposition is fairly straightforward. A decomposition reaction is a reaction in i beg your pardon a compound division down right into two or more simpler substances.

For instance, when an electric existing is passed through water (H2O), it deserve to be broken down right into hydrogen and also oxygen or H2 + O2. In this example, water is damaged down right into its 2 elements. The result is a chemical change because the beginning and finishing molecules room different.

You"ll notification that this chemical reaction needed electricity to happen. Decomposition reaction usually call for the applications of warm from an outside source, making that an endothermic reaction.

Keep in mental that no all decomposition reactions have actually to malfunction into your elemental forms. More facility substances with longer molecular chains may malfunction into smaller sized compounds instead of elements. An instance of this is when 2Fe(OH)3 (also recognized as ferric oxide) is exposed to heat. Rather of breaking into its individual molecules, it turns right into two compounds: Fe2O3 + 3H2O.

Example 3: Combination

Combination reactions, likewise called synthetic reactions, room the the opposite of decomposition reactions. These reactions happen when two substances (called reactants) are included together to produce one brand-new substance. And also because this is a chemical reaction, the an outcome is a molecular change!

One instance of this would certainly be a nail rusting. When this might seem prefer a decomposition reaction because it seems prefer the pond is decomposing and falling apart. However actually, it"s a chemical change! stole (Fe) and also oxygen (O) integrate to create the compound iron oxide (Fe2O3), i m sorry is rust. And as you can see, it likewise results in a fully new molecule.


What"s Next?

Understanding chemical and physical reaction in only one component of what you need to understand in stimulate to succeed on the AP Chemistry Exam. We"ve gathered with each other the most important AP Chem topics right into this can be fried guide.

Taking IB Chemistry instead? Here"s the complete IB Chemistry syllabus, a an extensive study guide, and also some examples of past papers from the IB Chemistry exam.

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