In your scientific research class, you may have heard that chemical and physical changes. However do friend know just how to phone call the difference between the two? The answer lies in even if it is or no a readjust to a substance results 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 specific chemical adjust examples and physical change examples to better understand their differences and also similarities.

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So let"s obtain started!


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

Physical readjust Definition

First, let"s talk around physical changes in chemistry. A physical readjust occurs once a problem or object alters its appearance, phase, or is used in a mixture. More importantly, a physical adjust does not change the molecular framework of a substance. And you deserve to reverse a physical change to recover all of the original 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 physics change? Things like cutting a item of paper in half, freeze water into ice or bending several of your mom"s favorite silverware (don"t execute that!) are all physical changes. That"s due to the fact that physical alters only affect a substance"s physics properties, not the ingredient of their molecules.

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


When logs burn, they experience a chemistry change.

Chemical readjust Definition

In contrast, a chemical readjust takes location when the initial substance"s that molecules space taken apart and also put back together into brand-new combinations that are different from the original combinations. Furthermore, the original matter cannot be recovered. And unlike physics changes, these alters usually usage a lot much more energy, such together heat and light, because the molecular bonds should be broken in order to rearrange them.

What is an instance of a chemical change, then? part chemical change examples incorporate a piece of record burning, a pond rusting, or baking a cake. Favor physical changes, it"s pretty clear the the means these things start and also end are quite different: a shining nail transforms orange v rust, and also wet dough i do not care a delicious dessert. The factors these space chemical alters is the the change happens top top a molecule level. Put another way, the object you begin with and the thing you end with are fully different substances.

So, let"s look in ~ some an ext examples that physical and chemical alters to much better understand the differences and similarities 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 at home!)

Physical change Examples

Earlier we talked around some instances of physical and chemical changes. However sometimes telling a physical readjust from a chemical change can be hard. This is specifically true when physical alters require or expend energy. The essential thing to remember is the in a physical change, the molecules remain the same.

Let"s look at three various physical readjust examples to much better understand this idea.

Example 1: phase Changes

Phase transforms involve transforms in size, volume, and density. For instance, as soon as you turn water into ice or vapor, this is dubbed a phase change. This is because water has actually 3 phases: solid (ice), fluid (water), and gas (vapor or steam).

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

Let"s take it a closer look at what"s keep going on a molecular level. Vapor is made up of H20 similar to the ice cream cube. The just difference in between vapor and ice is the the individual molecules have actually spread apart in vapor due to the applications of heat. Meanwhile, in ice, the molecules group closer together because of the absence of heat. Though these phase transforms require power to be expelled (exothermic reactions) or used (endothermic reactions), the number of atoms and also the form of the molecule in the substance remains the same. That"s what makes it a physics change!

Example 2: transforms in Size and also Shape


Like we pointed out earlier, physical alters are all around whether molecules remain the exact same or not. When things undergoes a physics change, that can end up being a different size and also shape as long as its composition continues to be the same.

Here"s what us mean: if friend have ever dropped a piece of glass ~ above the floor, you understand that it will certainly break apart, exploding into a million pieces. If girlfriend really wanted to, once you brushed up all the glass up into your dustpan, you could probably fit that all ago together (even though it would take a most time and also patience). This is additionally a physics reaction since the glass stays glass. As soon as it shatters, the glass changes size and shape, but its molecules don"t change.

This is a physical readjust that only involves a change in size and shape. While power helped break the glass into pieces, no power was offered to rearrange the molecules.

Example 3: mixtures & Solutions

Imagine you are on a day out at the beach. The sunlight is shining, the sand is warm, and also the seagulls room trying come steal people"s lunches. After playing in the waves because that a bit, you decision to do a sandcastle. Friend fill her bucket up with sand and also plop the upside down. The sand comes out yet it doesn"t rod together. Girlfriend forgot to add water! You try again, this time through water and voila, you"ve produced your very first tower favor a master sandcastle architect.

But why didn"t the sand stick with each other the first time? It needs to do through a physical property called surface tension. Surface tension refers to how strong the bond is in between a substance"s molecules. Water has actually a strong surface tension, so adding it come the sand create a solid enough bond because that the sand come cling together instead of falling apart.

What makes this different from a chemical reaction is the the sand and the water, though blended together, do not readjust their molecular structure. The water stays water and also the sand continues to be sand. And also if you to be to measure up the water the will at some point evaporate when the sandcastle dries, friend will uncover that the lot of evaporated water is same to the lot of fluid water you included to the sand originally.

This is called a mixture because both building materials (the sand and also the water) retain their own physical properties.

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

Solutions differ from mixtures in that they room homogenous. A single drop of saltwater would have actually the same variety of salt molecule (NaCl) per water molecule (H2O) as one more drop taken native the very same solution. In a mixture, you could have more sand 보다 water in two various handfuls, even if they were taken from the same bucket.

These physical readjust examples should aid you recognize the difference between a physical and also chemical change. Especially when you compare them to the chemical adjust examples below.


Dough transforming into bread is a tasty example of a chemical change.

Chemical adjust Examples

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

So how have the right to you phone call the difference in between a physical and a chemistry change? It all comes down to--you guessed it!--the molecules. In a physical change, the molecule stay precisely the same throughout the transformation. In a chemical change, however, it"s the molecule themselves the transform!

Here room three instances of chemical changes to assist you clues the difference!

Example 1: Combustion

Combustion is a chemical reaction between substances, usually including oxygen, the creates heat and also light. The power released through the reaction (in the form of heat and light) is resulted in by the break of molecule bonds. As a result, the initial substances transform into entirely various substances due to the fact that of the rearrangement that molecules, i beg your pardon is an example of a chemistry change!

For instance, if girlfriend mix oxygen (O2) through a kind of hydrocarbon referred to as methane (CH4), the molecule bonds of both substances space broken, which creates the heat and light. The bonds climate reform to develop two different molecules: carbon dioxide (CO2) and also water (H2O).

Combustion reaction can happen at various rates, too. An example of a sluggish reaction is a enhance burning. A fast reaction would certainly be dynamite exploding. The quantity of energy released in any combustion reaction depends on just how much power is needed to break the molecule bonds. The harder that is to break the bonds, the much more energy is released overall. But regardless of even if it is the reaction is fast or slow, combustion is a chemistry change.

Example 2: Decomposition

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

For instance, once an electric present is passed with water (H2O), it deserve to be broken down into hydrogen and also oxygen or H2 + O2. In this example, water is broken down into its two elements. The result is a chemical adjust because the starting and ending molecules are different.

You"ll an alert that this chemistry reaction needed electricity to happen. Decomposition reaction usually call for the application of heat from an exterior source, making that an endothermic reaction.

Keep in mental that no all decomposition reactions have to malfunction into their elemental forms. More complex substances with longer molecular chain may break down into smaller sized compounds rather of elements. An instance of this is when 2Fe(OH)3 (also well-known as ferric oxide) is exposed to heat. Instead of breaking into its separation, personal, instance molecules, it turns right into two compounds: Fe2O3 + 3H2O.

Example 3: Combination

Combination reactions, also called synthesis reactions, space the the contrary of decomposition reactions. These reactions take place when two substances (called reactants) are added together to create one brand-new substance. And because this is a chemical reaction, the an outcome is a molecular change!

One example of this would certainly be a nail rusting. While this may seem favor a decomposition reaction because it seems like the pond is decomposing and also falling apart. But actually, it"s a chemistry change! stole (Fe) and oxygen (O) integrate to produce the compound iron oxide (Fe2O3), i m sorry is rust. And also as you deserve to see, it also results in a totally new molecule.


What"s Next?

Understanding chemical and also physical reaction in just one component of what you need to recognize in stimulate to success on the AP Chemistry Exam. We"ve gathered with each other the most crucial AP Chem topics into this ultimate guide.

Taking IB Chemistry instead? Here"s the finish IB Chemistry syllabus, a substantial study guide, and also some instances of past records from the IB Chemistry exam.

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Need help understanding various other chemistry concepts? Learn exactly how to balance chemistry equations step-by step, what the 11 solubility rules are, and also when you have to use the solubility continuous (Ksp).