Density Chemical Or Physical Property

Learning Outcomes

Identify properties of and changes in thing as concrete or chemical
Identify properties of thing as extensive or intensive

The characteristics that enable us to distinguish one substance from some other are called properties. A physical property is a feature of matter that is not associated with a change in its chemical composition. Familiar examples of concrete backdrop include density, color, hardness, melting and boiling points, and electrical conductivity. We can find some concrete properties, such as density and color, without changing the physical state of the matter observed. Other concrete properties, such as the melting temperature of atomic number 26 or the freezing temperature of water, tin can only exist observed as thing undergoes a physical change. A physical change is a change in the state or backdrop of matter without any accompanying change in its chemical limerick (the identities of the substances contained in the matter). Nosotros observe a concrete change when wax melts, when saccharide dissolves in coffee, and when steam condenses into liquid water (Figure 1). Other examples of concrete changes include magnetizing and demagnetizing metals (as is washed with common antitheft security tags) and grinding solids into powders (which can sometimes yield noticeable changes in color). In each of these examples, there is a modify in the physical state, form, or properties of the substance, but no change in its chemical limerick.

Figure A is a photograph of butter melting in a pot on a stove. Figure B is a photograph of something being heated on a stove in a pot. Water droplets are forming on the underside of a glass cover that has been placed over the pot.

Figure 1. (a) Wax undergoes a physical change when solid wax is heated and forms liquid wax. (b) Steam condensing inside a cooking pot is a physical alter, every bit water vapor is inverse into liquid h2o. (credit a: modification of work past "95jb14"/Wikimedia Commons; credit b: modification of work by "mjneuby"/Flickr)

The change of one type of matter into another blazon (or the inability to change) is a chemic property. Examples of chemical backdrop include flammability, toxicity, acidity, reactivity (many types), and heat of combustion. Iron, for example, combines with oxygen in the presence of water to form rust; chromium does not oxidize (Effigy two). Nitroglycerin is very dangerous because information technology explodes easily; neon poses almost no run a risk because it is very unreactive.

Figure A is a photo of metal machinery that is now mostly covered with reddish orange rust. Figure B shows the silver colored chrome parts of a motorcycle. One of the parts is so shiny that you can see a reflection of the surrounding street and buildings.

Figure two. (a) One of the chemical backdrop of iron is that information technology rusts; (b) one of the chemical properties of chromium is that it does non. (credit a: modification of work past Tony Hisgett; credit b: modification of piece of work past "Atoma"/Wikimedia Commons)

A chemic alter always produces one or more than types of matter that differ from the thing nowadays before the change. The formation of rust is a chemical change because rust is a different kind of affair than the iron, oxygen, and water present before the rust formed. The explosion of nitroglycerin is a chemical change because the gases produced are very different kinds of thing from the original substance. Other examples of chemical changes include reactions that are performed in a lab (such equally copper reacting with nitric acrid), all forms of combustion (burning), and food being cooked, digested, or rotting (Figure iii).

Figure A is a photo of the flask containing a blue liquid. Several strands of brownish copper are immersed into the blue liquid. There is a brownish gas rising from the liquid and filling the upper part of the flask. Figure B shows a burning match. Figure C shows red meat being cooked in a pan. Figure D shows a small bunch of yellow bananas that have many black spots.

Figure 3. (a) Copper and nitric acid undergo a chemical alter to form copper nitrate and dark-brown, gaseous nitrogen dioxide. (b) During the combustion of a match, cellulose in the friction match and oxygen from the air undergo a chemic alter to form carbon dioxide and h2o vapor. (c) Cooking red meat causes a number of chemical changes, including the oxidation of iron in myoglobin that results in the familiar red-to-brown colour modify. (d) A assistant turning brown is a chemic change as new, darker (and less tasty) substances form. (credit b: modification of work by Jeff Turner; credit c: modification of work by Gloria Cabada-Leman; credit d: modification of work past Roberto Verzo)

Properties of matter fall into one of two categories. If the property depends on the amount of matter present, it is an extensive property. The mass and book of a substance are examples of all-encompassing properties; for instance, a gallon of milk has a larger mass and book than a loving cup of milk. The value of an extensive property is directly proportional to the amount of matter in question. If the property of a sample of thing does not depend on the corporeality of matter present, it is an intensive property. Temperature is an instance of an intensive property. If the gallon and cup of milk are each at 20 °C (room temperature), when they are combined, the temperature remains at twenty °C. As another case, consider the distinct but related properties of heat and temperature. A drop of hot cooking oil spattered on your arm causes brief, small-scale discomfort, whereas a pot of hot oil yields severe burns. Both the driblet and the pot of oil are at the same temperature (an intensive property), but the pot clearly contains much more than heat (all-encompassing property).

Hazard Diamond

You may have seen the symbol shown in Figure 4 on containers of chemicals in a laboratory or workplace. Sometimes called a "burn diamond" or "gamble diamond," this chemical hazard diamond provides valuable information that briefly summarizes the various dangers of which to be aware when working with a detail substance.

Figure 4. The National Fire Protection Agency (NFPA) hazard diamond summarizes the major hazards of a chemical substance.

The National Fire Protection Agency (NFPA) 704 Hazard Identification System was developed by NFPA to provide condom information about sure substances. The system details flammability, reactivity, health, and other hazards. Within the overall diamond symbol, the summit (blood-red) diamond specifies the level of fire gamble (temperature range for flash point). The blue (left) diamond indicates the level of wellness hazard. The xanthous (correct) diamond describes reactivity hazards, such every bit how readily the substance will undergo detonation or a trigger-happy chemical change. The white (bottom) diamond points out special hazards, such every bit if information technology is an oxidizer (which allows the substance to burn down in the absence of air/oxygen), undergoes an unusual or dangerous reaction with water, is corrosive, acidic, alkaline metal, a biological take chances, radioactive, and then on. Each hazard is rated on a scale from 0 to iv, with 0 being no hazard and 4 being extremely hazardous.

While many elements differ dramatically in their chemic and physical backdrop, some elements accept similar properties. We can identify sets of elements that exhibit mutual behaviors. For example, many elements carry heat and electricity well, whereas others are poor conductors. These properties can be used to sort the elements into three classes: metals (elements that conduct well), nonmetals (elements that conduct poorly), and metalloids (elements that have properties of both metals and nonmetals).

The periodic tabular array is a tabular array of elements that places elements with similar backdrop close together (Figure v). You will learn more well-nigh the periodic table as yous continue your study of chemistry.

Figure 5. The periodic table shows how elements may be grouped co-ordinate to sure like properties. Notation the background colour denotes whether an element is a metallic, metalloid, or nonmetal, whereas the element symbol color indicates whether it is a solid, liquid, or gas.

Cardinal Concepts and Summary

All substances have singled-out physical and chemical backdrop, and may undergo physical or chemic changes. Physical backdrop, such as hardness and boiling betoken, and physical changes, such as melting or freezing, do not involve a change in the limerick of matter. Chemical properties, such flammability and acidity, and chemic changes, such as rusting, involve product of matter that differs from that present beforehand.

Measurable properties fall into one of ii categories. Extensive properties depend on the amount of affair present, for case, the mass of gold. Intensive properties do not depend on the amount of thing present, for case, the density of golden. Heat is an example of an extensive property, and temperature is an example of an intensive property.

Try It

Allocate the half dozen underlined properties in the following paragraph as chemical or concrete: Fluorine is a pale yellowish gas that reacts with most substances. The free chemical element melts at −220 °C and boils at −188 °C. Finely divided metals burn down in fluorine with a bright flame. Nineteen grams of fluorine volition react with ane.0 gram of hydrogen.
Classify each of the post-obit changes as physical or chemical:
1. condensation of steam
2. called-for of gasoline
3. souring of milk
4. dissolving of sugar in water
5. melting of gilded
Allocate each of the following changes as physical or chemical:
1. coal burning
2. ice melting
3. mixing chocolate syrup with milk
4. explosion of a firecracker
5. magnetizing of a screwdriver
The volume of a sample of oxygen gas inverse from ten mL to 11 mL as the temperature inverse. Is this a chemical or concrete change?
A two.0-liter book of hydrogen gas combined with 1.0 liter of oxygen gas to produce two.0 liters of water vapor. Does oxygen undergo a chemic or physical change?
Explain the deviation between all-encompassing properties and intensive properties.
Identify the following backdrop as either extensive or intensive.
1. volume
2. temperature
3. humidity
4. heat
5. boiling point
The density (d) of a substance is an intensive belongings that is defined as the ratio of its mass (g) to its volume (V).[latex]\text{density}=\dfrac{\text{mass}}{\text{volume}}[/latex]; [latex]\text{d}=\dfrac{\text{g}}{\text{5}}[/latex]. Considering that mass and volume are both extensive properties, explain why their ratio, density, is intensive.

Glossary

chemical alter:change producing a different kind of matter from the original kind of thing

chemical property:behavior that is related to the change of ane kind of affair into another kind of matter

extensive holding:property of a substance that depends on the amount of the substance

intensive property:holding of a substance that is contained of the amount of the substance

concrete change:change in the state or properties of affair that does not involve a alter in its chemical composition