Why do scientists need to know the properties of matter? Such as solid, liquid and gas? All matter has physical and chemical qualities.
Physical qualities are characteristics that scientists may measure without affecting the content of the sample under investigation, such as mass, color, and volume (the amount of space filled by a sample) (the amount of space occupied by a sample). Chemical characteristics explain the typical capacity of a material to react to generate new compounds; these include its flammability and susceptibility to corrosion.
All samples of a pure material have the same chemical and physical characteristics. For example, pure copper is always a reddish-brown solid (a physical property) and always dissolves in weak nitric acid to generate a blue solution and a brown gas (a chemical property) (a chemical property).
Both vast and intense forms of a property’s physical manifestation are possible. The extensive characteristics of a material include mass, weight, and volume, and they change depending on how much of the substance is present.
On the other hand, intensive qualities are those that are independent of the quantity of the material and include things like color, melting point, boiling point, electrical conductivity, and physical state at a certain temperature. For instance, regardless of how much is looked at, elemental sulfur always has a melting temperature of 115.2 degrees Celsius and appears as a yellow, crystalline solid.
It does not conduct electricity and has a melting point of 115.2 degrees Celsius. When scientists want to identify the identification of a material, they often assess its intense qualities. On the other hand, the extensive properties communicate information about how much of the substance is present in a sample.
Despite the fact that mass and volume are both extensive characteristics, the ratio between the two is an essential intense feature that is denoted by the symbol. The term “density” refers to the ratio of a substance’s mass to its unit volume and is often written as grams per cubic centimeter (g/cm3). The density of a substance is proportional to the mass contained inside a certain volume.
For instance, due to the larger mass of lead, its density is much higher than the density of the same amount of air, just as the density of a brick is higher than the density of the same volume of Styrofoam. The density of a pure material remains the same regardless of the temperature or the pressure that it is subjected to:
At a temperature of 25 degrees Celsius, the density of pure water is 0.998 grams per cubic centimeter. Table 1.3.1 contains the average density of a variety of commonly encountered compounds. Take note that the ratio of mass to volume for maize oil is smaller than that of water. This indicates that maize oil will “float” when it is combined with water.
Changes in their physical characteristics do not involve the formation or breaking of any chemical bonds. This indicates that the same kinds of compounds or components are present at the conclusion of the change as were present at the beginning of the change.
Because the starting components and the finishing materials are same, the attributes (such as color, boiling point, and so on) will likewise be identical. The only thing that happens to molecules during a physical change is that they move about. The following are examples of several sorts of physical changes:
Shifts in the status quo (changes from a solid to a liquid or a gas and vice versa)
Dissociation of components in a blend
Deformation of the body’s structure (cutting, denting, stretching)
Creating solutions, which are specialized forms of mixes.
However, the components that make it up remain the same. Melting is an example of a physical change (Figure 1.3.3), since while the identity of the matter remains the same, certain characteristics of the material change throughout the melting process. Alterations to one’s physical appearance might be further categorized as either reversible or irreversible. Since an ice cube that has melted may be refrozen, melting is a physical change that can be reversed.
All changes in status that are caused by a change in the physical state may be reversed. Other changes of state include evaporation (the transition from liquid to gas), freezing (the transition from liquid to solid), and condensation (the transition from solid to liquid) (gas to liquid). A second example of a change in physical state that may be reversed is dissolution.
It is claimed that salt has reached the aqueous state when it is dissolved in water and becomes part of the water. By boiling out the water and leaving the salt behind, the salt may be reclaimed after it has been lost.
The breaking and/or formation of bonds between molecules or atoms is what causes chemical processes to take place. This results in the transformation of one material with one set of attributes (such as melting point, color, flavor, etc.) into another substance with a different set of properties. In many cases, reversing the effects of chemical changes is more difficult than reversing the effects of physical changes.
Burning paper is an excellent illustration of a chemical transformation. Burning paper, on the other hand, results in the production of new chemicals, in contrast to tearing paper, which only releases the chemicals already present in the paper (carbon dioxide and water, to be exact).
A further illustration of a chemical transition is provided by the production of water. Each molecule is composed of two atoms of hydrogen and one atom of oxygen that are bound together chemically.
Another instance of a chemical transformation is when natural gas is consumed in an appliance like a furnace. This results in the production of carbon monoxide. This time, before to the reaction, we have one molecule of methane, denoted by CH4, and two molecules of oxygen, denoted by O2.
Following the process, we will have two molecules of water, denoted by H2O, and one molecule of carbon dioxide, denoted by CO2. In this particular instance, not only has the outward appearance changed, but the molecular structure itself has also been altered. The chemical characteristics of the new substances are different from those of the qualities possessed by the old substances. Consequently, this must be a chemical reaction.
In addition to being a physical transformation, the burning of magnesium metal results in a chemical transformation (magnesium + oxygen = magnesium oxide):
2Mg+O2=2MgO, much like how iron rusts when it’s exposed to oxygen (iron + oxygen = iron oxide/rust):
We are able to differentiate one sample of matter from the others by making use of the components of composition and qualities.
Comparing and contrasting student perspectives with scientific findings
The study conducted on students’ conceptualizations of solids, liquids, and gases confirms that their early knowledge of these categories is impacted by the way in which they use these words in their daily lives. Students are often heard using the term “solid” as an adjective rather than in the context of a group of substances, as would be more appropriate.
When students are asked to offer instances of each condition, the majority of the time, they are able to provide several examples of solids, fewer examples of liquids, and just a few examples of gases, which is reflective of the students’ everyday experiences. In general, one may recognize solids as being things that can be held, liquids as being things like “dishwashing liquids” that are “runny” or “wetting,” and gases as being things like LPG gas or propane gas that can be burned.
It would suggest that everyday language has a significant impact on early pupil identity. When students are asked given examples of chemicals that are found in each state, they typically reply responses such as “solid steel,” “liquid detergent,” and “camping gas.”
Some students have the firm belief that in order for a material to be considered a solid, it must be very tough and obviously solidified into lumps that cannot be broken apart. Students often classify as liquids materials that, to the naked eye, have the appearance of powders or small grains, such as talc or sand, due to the fact that these materials may be molded or poured with relative ease.
Because it does not “wet” items that are submerged in it, some pupils feel at ease with the notion that powder is a solid. Students often use water and other liquids that are mostly composed of water as examples of liquids. Some of these examples are milk, sea water, cordial, and lemonade.
Cooking oils, kerosene, mineral turpentine, paraffin oil, and oil-based paints are examples of non-water-based liquids that are seldom named. Other examples include oil-based paints. Students seem to effortlessly link liquids with water or incorrectly think that all liquids include some water just because they are liquids.
Research: McGuigan, Qualter & Schilling (1993), Krnel, Watson & Glazar (1998)
When studying topics at lower levels, it might be helpful to distinguish when different substances change state based on their placement in one of the three states of matter: solid, liquid, or gas (i.e. melt, boil, evaporate or freeze). Problems may arise, however, due to the fact that this categorization scheme is somewhat straightforward, whereas the make-up of matter is notoriously difficult to pin down.
It is difficult, if not impossible, to categorize many different kinds of compounds. Instances of “fuzzy” examples that are resistant to simple categorization include hair gel, toothpaste, mayonnaise, play dough, and Oobleck (made from a combination of corn starch and water). In light of the constraints imposed by this categorization scheme, the following are some concepts that may serve as working definitions for solids, liquids, and gases:
The most accurate definition of a solid is one that describes it as having a fixed volume and being able to keep its form even when subjected to moderate amounts of stress.
Liquids, like solids, have a fixed volume, but they may readily conform their shape to that of the container in which they are contained by spreading out to produce a flat surface. It is claimed of them that they “flow” readily, that they are “runny” or that they “wet,” and that they can tolerate somewhat compressive stresses.
Alterations to a material’s pressure as well as its temperature both have the potential to bring about changes in the physical properties of the substance. Melting occurs at a single melting point, however other compounds, like butter and chocolate, soften throughout a range of temperatures rather than at a single point.
This makes it considerably more challenging to explain these substances. Gels, colloids, immersions, and a great number of other compounds defy straightforward categorization because they comprise mixes of components that may exist in a variety of states throughout a wide temperature range.
The goal of categorization is to identify groups of items based on their shared or comparable characteristics.
The states of matter may be categorized in a straightforward manner by using solids, liquids, and gases; however, these are not the only classifications that scientists make use of.
There are certain compounds that are very challenging to “classify.”
The classification of states of matter has its drawbacks, although it may still be helpful in certain situations.
A shift in temperature may induce a change in the condition that a material is in.
Utilizing the Concept Development Maps: States of Matter, you may investigate the connections that exist between various concepts about the states of matter.
When instructing students on changes in state, it is essential to stress that a material continues to be the same even after transitioning from one state to another (for instance, melting from a solid to a liquid), even if the state in which it is found may have changed. Students commonly have the misconception that a change in state results in the creation of a whole new substance with completely unique features.
This makes sense when one considers the inherent distinctions that exist between the characteristics of the different states. In order to reassure students that the content is still the same even when it seems to act differently, it is crucial for teachers to carefully choose the terminology they use during class discussions.
Some pupils who are particularly perceptive may wonder why we can not see frozen carbon dioxide (also known as dry ice) in a liquid condition. Carbon dioxide undergoes a process known as sublimation, in which it transforms from a frozen solid (dry ice is solid below -79°C) into a gas without exhibiting any signs of forming pools of liquid.
This is due to the fact that maintaining its liquid condition calls for a pressure that is roughly sixty times higher than the standard atmospheric pressure. Students could explore the fact that when the substance changes from a solid to a liquid, it immediately begins to boil and transform into a gas. Another chemical that evaporates into vapor when brought to ambient temperature is naphthalene, which is used in the production of mothballs.
Students should work in small groups and be given a variety of common objects (such as mixed buttons) composed of different substances. The students should then be tasked with developing a system for classifying the objects in a way that will assist in identifying properties or characteristics that are shared by the objects.
Their classifications could be based on factors like as color, hardness, naturalness, how they feel, or how helpful they are. It is possible that asking students to name only three characteristics that are shared by all of the objects in the grouping will be adequate. The students may either cut and paste photographs into sheets, or they could create tables to organize the data.
In order to do this work successfully, you need to pay careful attention to picking things that have evident common qualities. In the course of the class discussion, you should strive to encourage the viewpoint that all of the characteristics that were used to classify the items are valid; however, certain groupings (systems of classifying) may be more helpful than others in determining which characteristics are usefully shared by a group.
Encourage students to think about a broad variety of appropriate settings that have significant ties to their day-to-day experiences when you are having conversations in the classroom. Consider situations in which the condition of the matter is changing, such as the drying of garments, the melting of butter, and the dripping of frozen poles.
Try to get students to look beyond of the typical examples of water, frozen water, and water vapor in their thinking. Talk about how chocolate, sugar, and candle wax all melt, as well as the experiences that some children will have had with frozen carbon dioxide (dry ice).
In a presentation using the Predict-Observe-Explain (POE) method, use the examples of dry ice and naphthalene to illustrate that some substances may change state directly from a solid to a gas without first becoming a liquid. Explore the several methods that students might use to recognize that a gas is being given out by either of these solid objects.
Students have the ability to identify the odor of naphthalene gas. Put a few pieces of dry ice in an empty balloon, then tie a knot around the balloon’s neck to keep the dry ice in place. As the solid transforms into a gas, the balloon will expand as a result. Alternately, you may produce gas bubbles by putting dry ice pellets into a glass of water and watching the reaction.
(It is important to keep in mind that the fog that is formed is not carbon dioxide gas but rather minute droplets of liquid water that become visible when cold gas is mixed with humid air.) This is a second transition that takes place as a result of this event.
Give the pupils chemicals that are difficult to categorize so that they are forced to reevaluate their definitions and how they currently comprehend the categorization system. Students are at the right level to understand that it is okay for them to recognize that some drugs are less difficult to handle and do not need containers in order for them to be distributed (solids).
Certain compounds may be handled only if they are contained in open containers because they have a “runny” consistency; other substances, on the other hand, cannot be handled at all and must be stored in sealed containers (gases). After students have a solid understanding of this system of obvious classification, they could be given substances that present greater challenges, such as toothpaste, sand, hair gel, Ooble k, or granulated sugar.
This would be possible once students have developed a strong understanding of the system. The assumption that all chemicals can be simply categorised will be called into question as a result of the classification of these objects.
They get an understanding of the similarities and contrasts in the characteristics of these many materials and substances, including how they seem, how they feel, and how they change. Students might begin to organize their knowledge of common materials and substances by using the categories of “liquid” and “solid” as a starting point.
It is essential to have a solid understanding that matter may exist in any condition and can also alter the state in which it is found. This may happen either via the consumption of energy or the release of energy, and it is often connected with changes in both temperature and pressure. One easy illustration of this is water. If you break off a piece of ice, you are left with frozen water.