If you’re curious about physical changes, look no further. We’ve got the answer you’re looking for!
“Everything is in a state of flux, including the status quo.” – Robert Byrne
Physical changes are often simpler to understand than chemical changes because they don’t involve any alteration in what makes up the substance itself. So, how do we tell when something’s changed physically? And more importantly, why does it matter?
In this blog post, we’ll be exploring some different scenarios and discovering which ones qualify as examples of physical change. Understanding the difference between physical and chemical changes may not seem crucial in your day-to-day life, but it can help develop a deeper appreciation for the science behind many everyday phenomena.
So whether you’re a curious student or just looking to expand your knowledge base, read on to find out the answer to the question at hand: What are some scenarios that exemplify a physical change?
Definition of Physical Change
A physical change is a type of change in which the identity of the matter remains the same, but some of its properties are altered. In other words, when substances undergo physical changes, they retain their original chemical composition, and no new substances are formed.
The key feature that distinguishes physical changes from chemical ones is:
- No new substance(s) is/are formed after a physical change occurs.
- The process can often be reversed via different methods such as evaporation, sublimation, filtration, boiling, freezing, or cutting.
Nature of Physical Change
Physical changes involve altering measurable properties of matter without altering its chemical composition. Matter exhibits different characteristics before and after undergoing these changes, although it still retains its fundamental substance nature.
This begs us to ask why an object might alter its observable characters instead of changing into something else entirely?
“A physical change must exist where there is little or no alteration with regards to the forces acting upon the field around the object.” -Quanta Magazine
Therefore, we observe physical changes more frequently than chemical ones because many objects shift shape, size, phase, or structure due to temperature and pressure differences or passing through different media like air, water, glass, gel, etc.
Characteristics of Physical Change
All physical shifts do not lead to significant changes in mass, volume, or density, but rather affect states of matter (either solid, liquid, or gas), shape, color, taste, texture, odor, melting/boiling point, solubility, viscosity, and magnetism among others. Here are four critical characteristics of physical changes;
- No new substances are formed: During a physical change, the elements can alter their state or size and shape without changing into entirely different molecules.
- Matter remains chemically unchanged: The chemical composition of the substance undergoing change in any way doesn’t change during a physical modification process. It’s only that one or more observable traits have transformed.
- Reversible Process: One essential feature that distinguishes them from other forms of modifications is that they’re often reversible with respect to processes such as filtration, melting/freezing, etc.
- Energy exchanged: Another characteristic of physical changes is that energy is usually given off or absorbed during these transitions. This happens when heat-conducting object interacts with temperature differences by releasing kinetic activity alongside reactions involved in producing this energy rebounded at large impact levels.
Examples of Physical Changes
Physical shifts occur all around us every day in things we see and interact with. Temperature and pressure fluctuations lead to some form of material alteration like expanding, contracting, ripening, melting, boiling, freezing, breaking apart, or just simply changing colors. Here are a few examples of everyday physical alterations that occur daily;
- A piece of ice melting (solid –> liquid)
- Burning wood resulting in ash (solid –> gas + solid)
- Cooling tea allowing it to precipitate out solids (liquid –> solid + liquid)
- Heating copper until it becomes malleable enough to make electrical wires (solid –> liquid)
- Washing clothes using a washing machine (solids –> liquids to remove dirt).
All of these are examples of physical changes because (i) no new substances are formed, (ii) the matter doesn’t change chemically in any way, (iii) the modifications are reversible to their original form(s), and (iv) energy is involved.
Importance of Physical Change
The importance of understanding how things can transform physically is that we could know when certain materials could be used to our advantage. For example, knowing that such mineral X compresses into a useable shape due to pressure during a manufacturing process can help make better construction decisions. Additionally, this knowledge helps us study atomic behavior to predict outcomes on the nano-scale level so that engineers may design, say, devices based on elemental behaviors in those scenarios.
Familiarity with physical changes enables you to identify whether processes involves transformation via chemical reaction or it’s simply a surface modification more suited to mechanical means than other methods.
“Physical chemistry shapes what we see; it affects how and why an instrument works… It’s everything about making science interesting and celebratory.” -Ahmed Zewail
Moreover, the distinction between the two types of alterations becomes even more important within lab settings where physicists and chemists exert great care not to cause cross-contamination accidentally and ruin results for experiments by mixing inconsistent variables.
Physical shifts refer to anything that alters observable characters without changing the underlying identity of the substance. These alterations take place due to gradual temperature and pressure fluctuations that lead to state changes like solid, liquid, or gas. They involve breaking down complex substances into simpler ones slowly but surely, which makes them integral to basic material sciences, engineering processes, and performing wide scientific research.
Examples of Physical Changes
Physical changes are those where the molecular composition of a substance is not altered, but rather they typically involve a transformation in its physical state. This can mean a shift from solid to liquid, liquid to gas or vice versa, as well as other transformations such as changing shape or size. Here we will explore two examples that demonstrate physical changes in matter.
Melting of Ice
One clear instance of physical change happens when ice melts. At zero degrees Celsius, pure water freezes and hardens into its crystalline structure as ice. In contrast, by increasing the temperature above this threshold point, for example on a hot day, it starts melting, causing a visible transformation to our perception.
The process requires an infusion of energy in order to break down the hydrogen bonds between adjacent molecules, meaning the absorbance of heat makes them vibrate increasingly until their arrangement and position shift indistinctly due to attraction and repulsion forces, leading eventually to a disordered liquid state. Meanwhile, the intrinsic chemical properties of these molecules remain unaltered: the water still has the same characteristics and remains composed of two hydrogen atoms covalently bonded with one oxygen atom (H2O).
“The intermolecular bonding within substances determines whether the matter exists in the solid, liquid or gaseous physical states” – Daniel R. Jeske
Freezing of Water
The reverse phenomenon is also true: freezing produces significant modifications in appearance, yet without altering the innate atomic or molecular properties. For instance, imagine putting a glass of water inside a freezer overnight; at 0°C or lower temperatures, the thermal agitation diminishes progressively, encouraging the stabilization of the lattice-like cellular configuration that was achieved originally at the moment of freezing point. Yet ice is not only used for cooling drinks. In fact, it has numerous important uses in the medical and industrial fields because of its physical and chemical stability.
Other examples of physical changes include dissolution (Homogeneous mixture between two substances), deformation of solids or gases by external forces or change (Regulation to another type, often with clear indications such as color alteration) from one state to another.”
“The material world around us undergoes constant change, every second of every day” – Stephen Hawking
Transformations that do not have a profound effect on the molecular composition of matter are noteworthy cases of physical change. These effects range across different states and properties, although they share similarities including visible shifts in appearance, modifications of characteristics, reception/application of thermal energies and more.
Scenario 1: Melting of Ice
The topic of physical changes is an essential part of our lives. We experience it daily, but we may not be aware of the science behind these processes. One common example of a physical change is melting ice.
Process of Melting
Melting is the process by which a substance turns from its solid-state into a liquid state due to an increase in temperature. When heat energy is applied to a solid-state substance like ice, it increases the translational kinetic energy of its molecules. The molecules then vibrate more quickly and break away from their fixed positions. This causes them to overcome the forces that hold them together as a solid, leading to the transition into a liquid form.
Factors Affecting Melting
The rate of melting depends on various factors such as external temperature, atmospheric pressure, surface area, and particle size. For instance, if the external temperature is below the freezing point of water, ice cannot melt. Similarly, an increase in atmospheric pressure can delay the melting of ice since this added pressure raises the melting point of water. On the other hand, increasing the external temperature or offering sufficient energy will speed up the melting process.
Observations during Melting
Different observations are made while ice melts, including a decrease in the visible volume, changing color, and fluctuations in density. During melting, there is a noticeable reduction in the visible volume occupied by the original object; however, the mass remains constant. Another observation is that the apparent intensity of white color decreases with time, usually followed by a transparent layer formation at the bottom of the body. Changes also occur in the molecular arrangement, which subsequently affects the density of the object. When transitioning from a solid to liquid phase, most materials’ density reduces due to a less crowded molecular structure.
Applications of Melting in Daily Life
Melting is an essential process in our daily lives, and we may not notice it or think about its significance. An instance where melting plays an important role is during cooking. Cooking involves applying heat to solid food materials like ice to melt them into liquids for easier digestion. Similarly, the use of powdered milk means that people who don’t have easy access to dairy products can prepare fresh milk effortlessly by mixing powder with hot water. Another application is in manufacturing processes such as metal casting, injection molding, glassblowing, and 3D printing. These manufacturing methods all require precise temperature regulation and melting of specific substances to create a final product.
Scenario 2: Burning of Paper
Process of Burning
Burning of paper is an example of a physical change. It is a chemical process that involves the breaking and making of chemical bonds in cellulose, hemicellulose, and lignin (the main constituents of wood and paper) when exposed to high temperatures as a result of heat energy.
The combustion of paper requires three essential elements- heat, fuel (paper), and oxygen. When one of these factors is absent, burning cannot occur. The heat breaks down the cellulose molecule into simple sugars which then mix with oxygen present allowing for processing that sparks a flame.
Initially, external heat sources such as a matchstick or lighter are applied to paper surfaces leading to ignition. As minor combustion starts at the corner of paper, it generates enough heat to decompose complex molecules thus creating flammable gases that spread throughout the structure.
The burning continues while there’s still sufficient heat generation and availability of oxygen until all the fuel has been consumed or put off through natural occurrences like drenching in water.
Factors Affecting Burning
Several variables can influence the rate, temperature, intensity, and duration of burning. These factors include:
- Paper Composition : Different types of paper vary based on numerical properties. Some papers ignite faster than others due to their distinct compounds and thicknesses. Newsprints, cardboard boxes burn more quickly since they have less compactness and suitable size creating huge contact areas
- Oxygen: High levels of Oxygen support extensive penetration of flames inside the structure causing rapid damage. Low-oxygen concentrations make it impossible for burning materials to receive adequate air making them go out swiftly.
- Temperature : High temperatures sustain burning, reaching and surpassing the ignition threshold of other materials nearby. Different types of paper have different ignite temperature thresholds due to distinct chemical or composition properties.
- Humidity levels: Moisture affects the surface ignitability of papers as wet surfaces take longer duration than dry ones before combustion sparks off.
“The cause of fire is the presence of heat-energy combined with oxygen molecules. If any factor changes significantly from the operational norms then filling of all combustible material can occur resulting in a massive incident.”-Anonymous
The burning of paper is an example of physical change because there’s no formation of new elements during burning, only chemical bonds break down into simpler particles providing fuel for further reactions and production of energy. Among the factors affecting combustion include temperature; humidity, composition type; etc., thus making it necessary for individuals to be aware of them while handling flammable materials.
Scenario 3: Dissolving Salt in Water
A physical change is a type of change where the substance involved remains the same; its chemical composition does not alter. Dissolving salt in water is an example of a physical change.
Process of Dissolving
Dissolving is when one substance disperses evenly throughout another substance. The process of dissolving salt in water involves breaking the electrostatic bonds holding the ions together and surrounding them with water molecules. Ions form when the salt splits, meaning they have either more or fewer electrons than protons leading to positive or negative charges. These ion/water combinations are called hydration shells, that ‘powerfully trap’ each salt ion, allowing it to dissolve (source).
Factors Affecting Dissolving
“The solubility of a solute in a solvent depends on several factors such as molecular size, shape, and charge of the solute molecule, temperature, pressure, and polarity of the solvent.”
The solubility of salts like sodium chloride increases with temperature because higher temperatures can break the bonds between the ions more effectively. Pressure affects mostly gases by increasing their solubility up to a specific point. Solvents with similar polarities tend to dissolve well within themselves since like dissolves like (source).
Observations during Dissolving
Salt dissolving in water results in a clear liquid. Initially, adding granulated table salt formed clumps at the bottom of a small glass beaker but quickly dispersed when stirring. During this physical reaction, no gas was released into the air, nor did the appearance or odor of the substances transform significantly – both passed through the filter looking exactly the same, just without clumped pieces of solid salt.
Applications of Dissolving in Daily Life
Dissolving salt in water has many everyday applications, with some of the most common being in cooking and cleaning. Saltwater boils at a higher temperature than freshwater, making it useful for cooking pasta or other foods that require large amounts of hot water (source). Additionally, during winter deicing driven by municipal road services, salt distributed on roads lowers the waters freezing point allowing icy snow to transform into liquid pavement-sludge.
Conclusion: Identifying Physical Change Vs Chemical Change
Differences between Physical and Chemical Changes
A physical change is a change in which no new substance is formed, but the appearance or state of the matter changes. On the other hand, chemical change is a change in which a new substance is formed with different properties from the original one. For instance, when we melt an ice cube, water is formed, but it still remains water even after cooling it again. This is an example of a physical change. But if we mix bleach and ammonia in a bowl, poisonous gas is produced that has completely different properties than both the chemicals combined. This process is an example of chemical reaction.
- Physical change doesn’t form any new substances whereas chemical change produces new substances.
- Physical change can be reversed, but chemical change cannot reverse easily.
- Physical change only alters the form of matter while its composition remains the same. However, chemical change causes alteration to the molecular structure; hence, these have altered properties too.
Importance of Identifying Physical and Chemical Changes
Identifying physical changes versus chemical changes is essential for many reasons.
Knowing whether a particular phenomenon belongs to which category helps a chemist choose which method would help separate and analyze individual components accurately. In everyday life, knowing how substances react is crucial to understand their usage.
Examples of Physical Changes
New states of matter often constitute examples of physical changes like melting, freezing, vaporizing or condensing solid or liquid material. Similarly, cutting hair, grinding coffee beans, bending metals, inflating balloons, bursting crackers, tearing paper, etc., also belong to physical changes. Another popular example of a physical change is the color of metals turning from shiny to tarnished brown when exposed to air and water for long years.
Examples of Chemical Changes
Some examples of chemical changes include:
- Burning wood or paper, which produces ashes amid diffusing smoke with an extremely distinct odor that is nothing like the original material.
- A rusting process changes iron into hydrated ferric oxide, compositionally different than its initial constituent.
- The process of digestion involves multiple chemical reactions involving enzymes changing complex molecules throughout the food into smaller ones.”
“Chemical and Physical changes can be difficult to distinguish, but it’s worth keeping in mind that chemical changes are usually much harder to reverse and can create new substances if two chemicals are brought together. Reversible physical changes generally involve a temperature or state alteration.” -Kiera Mclaughlin
Being skilled at identifying physical and chemical changes could save us tons of time, money, and energy on various things that require these skills as they play a significant importance in our daily lives. Hence, we must pay close attention to the phenomena that occur around us to understand their applications and differentiate between vital concepts to help make better decisions regarding them.
Frequently Asked Questions
What is a physical change?
A physical change is a change in the physical properties of matter, such as shape, size, texture, and state, without changing its chemical composition. It is a reversible change that does not alter the identity of the substance. Examples of physical changes include melting ice, freezing water, crushing a can, and tearing paper.
How is physical change different from chemical change?
Physical change differs from chemical change because chemical change involves a chemical reaction that results in the formation of a new substance with different properties. In contrast, physical change only alters the physical properties of a substance, such as its appearance or state, without changing its chemical composition. Chemical changes are usually irreversible, while physical changes can be reversed.
Which scenario is an example of a physical change: melting ice or burning paper?
Melting ice is an example of a physical change because it changes the state of water from solid to liquid without altering its chemical composition. Burning paper, on the other hand, is an example of a chemical change because it involves a chemical reaction that produces new substances, such as ash and smoke.
What are some common examples of physical changes in everyday life?
Physical changes occur frequently in everyday life. Some common examples include boiling water, melting butter, cutting vegetables, crushing ice, and tearing paper. These changes alter the appearance or state of the substance without changing its chemical composition. Other examples include changing the shape of clay or molding dough.
How can you tell if a change is physical or chemical?
You can tell if a change is physical or chemical by observing whether the chemical composition of the substance has changed. If the change only alters the physical properties of the substance, such as its appearance or state, it is a physical change. If the change results in the formation of a new substance with different properties, it is a chemical change.
What are some factors that can cause physical changes to occur?
Physical changes can occur due to several factors, such as changes in temperature, pressure, and force. Heating or cooling a substance can cause it to change its state, while applying force can change its shape or size. Changes in pressure can also cause physical changes, such as the compression or expansion of gases. Other factors that can cause physical changes include mixing substances, dissolving solutes, and evaporating liquids.