How Are Physical And Chemical Changes Similar

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In your scientific discipline class, you may have heard of chemical and physical changes. But do yous know how to tell the departure between the ii? The answer lies in whether or non a alter to a substance results in its molecules being rearranged.

In this article, nosotros will define chemical and physical and changes. Then nosotros'll take a look at specific chemical alter examples and physical change examples to ameliorate understand their differences and similarities.

So let's get started!

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

Physical Alter Definition

First, let's talk about physical changes in chemistry. A physical alter occurs when a substance or object changes its advent, phase, or is used in a mixture. More importantly, a physical alter does not alter the molecular structure of a substance. And yous tin contrary a physical alter to recover all of the original thing, even if it doesn't look exactly the same. In other words, in physical changes, the molecules from before and after the change stay the aforementioned!

What is an example of a concrete change? Things like cutting a piece of paper in half, freezing water into ice or bending some of your mom's favorite silverware (don't practise that!) are all physical changes. That's because physical changes but touch on a substance's concrete backdrop, not the composition of their molecules.

Even so non sure near what constitutes a concrete change? Don't worry: we'll dig into more concrete change examples in just a minute.

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When logs burn, they undergo a chemical modify.

Chemical Change Definition

In contrast, a chemical change takes place when the original substance's of molecules are taken apart and put back together into new combinations that are different from the original combinations. Furthermore, the original matter cannot be recovered. And unlike concrete changes, these changes commonly utilize a lot more energy, such equally heat and light, because the molecular bonds demand to be broken in order to rearrange them.

What is an case of a chemical alter, then? Some chemic change examples include a piece of paper burning, a nail rusting, or blistering a cake. Similar concrete changes, it's pretty articulate that the manner these things start and end are quite different: a shiny nail turns orange with rust, and moisture dough becomes a delicious dessert. The reasons these are chemical changes is that the modify happens on a molecular level. Put another style, the object you begin with and the object you end with are completely dissimilar substances.

So, let's look at some more examples of physical and chemical changes to improve understand the differences and similarities between the ii.

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When this mallet hits the egg, the egg will undergo a (very messy) physical modify. (P.S: Don't try this at home!)

Physical Change Examples

Before we talked about some examples of physical and chemical changes. But sometimes telling a concrete modify from a chemical change can exist hard. This is especially true when concrete changes crave or expend energy. The important thing to remember is that in a physical change, the molecules remain the same.

Allow's look at three different physical change examples to ameliorate sympathise this idea.

Example one: Phase Changes

Stage changes involve changes in size, book, and density. For example, when you plow water into ice or vapor, this is chosen a stage change. This is because h2o has iii phases: solid (ice), liquid (water), and gas (vapor or steam).

It may seem like some of the water molecules are lost during each phase change: the ice cube gets smaller, and steam seems to disappear into the air. Nevertheless, in each of these three stages, the water molecules stay the same. And if yous were to cool downwardly the vapor, it would reform into water. Cool it down enough, and it would plough back into water ice. There would be the same corporeality of hydrogen and oxygen atoms in the ice cube as there were in the steam, and these atoms volition stay in the same molecular shape in all stages.

Permit's take a closer look at what's happening on a molecular level. Vapor is made upwardly of H20 just like the ice cube. The merely difference betwixt vapor and ice is that the individual molecules accept spread apart in vapor due to the application of heat. Meanwhile, in ice, the molecules grouping closer together because of the absence of heat. Though these phase changes require energy to be expelled (exothermic reactions) or practical (endothermic reactions), the number of atoms and the shape of the molecules in the substance remains the aforementioned. That'south what makes it a physical change!

Example 2: Changes in Size and Shape

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Like we mentioned earlier, physical changes are all virtually whether molecules stay the same or non. When an object undergoes a physical change, it can become a unlike size and shape as long as its composition stays the aforementioned.

Here's what we mean: if you take always dropped a piece of glass on the floor, you know that information technology volition pause autonomously, exploding into a million pieces. If y'all actually wanted to, once you swept all that glass up into your dustpan, you lot could probably fit information technology all back together (even though it would take a lot of time and patience). This is as well a physical reaction because the glass stays drinking glass. When it shatters, the drinking glass changes size and shape, simply its molecules don't modify.

This is a concrete change that only involves a change in size and shape. While energy helped shatter the drinking glass into pieces, no free energy was used to rearrange the molecules.

Case 3: Mixtures & Solutions

Imagine you are on a 24-hour interval out at the beach. The sunday is shining, the sand is warm, and the seagulls are trying to steal people's lunches. After playing in the waves for a flake, you decide to make a sandcastle. You fill your saucepan up with sand and plop it upside downwardly. The sand comes out but information technology doesn't stick together. You forgot to add water! Yous effort again, this time with h2o and voila, y'all've created your first tower similar a main sandcastle architect.

But why didn't the sand stick together the beginning time? It has to practice with a physical property chosen surface tension. Surface tension refers to how stiff the bail is betwixt a substance's molecules. Water has a strong surface tension, so adding it to the sand creates a potent plenty bond for the sand to cling together instead of falling apart.

What makes this different from a chemic reaction is that the sand and the water, though mixed together, exercise not change their molecular structure. The water stays h2o and the sand stays sand. And if you were to measure out the h2o that will eventually evaporate once the sandcastle dries, yous volition notice that the amount of evaporated water is equal to the amount of liquid h2o y'all added to the sand originally.

This is chosen a mixture because both substances (the sand and the h2o) retain their own physical backdrop.

The aforementioned is true if you add table salt or sugar to water. Information technology seems like the salt and saccharide deliquesce and form new molecules. But if you were to await for the water to evaporate, you would observe that the salt or carbohydrate molecules become left behind in the glass. This is chosen a solution.

Solutions differ from mixtures in that they are homogenous. A unmarried drib of saltwater would have the aforementioned number of table salt molecules (NaCl) per water molecules (H2o) as another driblet taken from the same solution. In a mixture, y'all might accept more sand than water in 2 different handfuls, even if they were taken from the same saucepan.

These physical change examples should help you recognize the difference between a physical and chemical change. Particularly when you compare them to the chemical change examples below.

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

Chemical Change Examples

Both concrete and chemical changes result in ane thing turning into another. Whether it'south a drinking glass breaking or burning a slice of paper, the original detail becomes something dissimilar.

And so how tin you tell the difference between a physical and a chemical change? Information technology all comes down to--you guessed information technology!--the molecules. In a physical change, the molecules stay exactly the same throughout the transformation. In a chemical change, nevertheless, information technology's the molecules themselves that transform!

Hither are three examples of chemical changes to help you spot the difference!

Instance ane: Combustion

Combustion is a chemical reaction betwixt substances, usually including oxygen, that creates heat and light. The energy released by the reaction (in the form of heat and light) is acquired past the breaking of molecular bonds. As a issue, the original substances transform into entirely different substances because of the rearrangement of molecules, which is an example of a chemic alter!

For case, if you mix oxygen (O2) with a type of hydrocarbon called methane (CH4), the molecular bonds of both substances are broken, which creates the heat and calorie-free. The bonds and so reform to create two different molecules: carbon dioxide (CO2) and water (H2o).

Combustion reactions can occur at different rates, also. An instance of a slow reaction is a match burning. A fast reaction would exist dynamite exploding. The amount of energy released in whatever combustion reaction depends on how much energy is needed to break the molecular bonds. The harder information technology is to pause the bonds, the more free energy is released overall. But regardless of whether the reaction is fast or slow, combustion is a chemical change.

Example 2: Decomposition

Decomposition is rather straightforward. A decomposition reaction is a reaction in which a compound breaks down into 2 or more simpler substances.

For instance, when an electric electric current is passed through water (H2O), it can be broken downward into hydrogen and oxygen or H2 + O2. In this instance, water is cleaved downward into its two elements. The consequence is a chemical change considering the starting and ending molecules are different.

Y'all'll notice that this chemic reaction needed electricity to happen. Decomposition reactions ordinarily crave the application of oestrus from an outside source, making information technology an endothermic reaction.

Go along in listen that not all decomposition reactions have to break downwards into their elemental forms. More complicated substances with longer molecular chains may intermission downwards into smaller compounds instead of elements. An instance of this is when 2Fe(OH)3 (also known every bit ferric oxide) is exposed to heat. Instead of breaking into its individual molecules, it turns into 2 compounds: Fe2O3 + 3H2O.

Instance 3: Combination

Combination reactions, also called synthesis reactions, are the opposite of decomposition reactions. These reactions occur when two substances (called reactants ) are added together to create one new substance. And because this is a chemic reaction, the result is a molecular modify!

Ane example of this would exist a nail rusting. While this may seem similar a decomposition reaction because information technology seems similar the nail is decomposing and falling autonomously. Only actually, it'south a chemical alter! Iron (Iron) and oxygen (O) combine to create the compound fe oxide (Fe2O3), which is rust. And as you tin can run across, it besides results in a completely new molecule.

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What'south Next?

Understanding chemical and physical reactions in only one part of what you need to know in lodge to succeed on the AP Chemistry Exam. We've gathered together the near important AP Chem topics into this ultimate guide.

Taking IB Chemistry instead? Here'southward the complete IB Chemical science syllabus, a comprehensive report guide, and some examples of past papers from the IB Chemistry test.

Need assist agreement other chemistry concepts? Learn how to balance chemic equations stride-by pace, what the 11 solubility rules are, and when you lot need to use the solubility constant (K _sp ).

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About the Author

Ashley Sufflé Robinson has a Ph.D. in 19th Century English Literature. As a content writer for PrepScholar, Ashley is passionate nigh giving college-bound students the in-depth information they need to get into the school of their dreams.