Identify nature of and changes in issue as physics or chemicalIdentify properties of issue as comprehensive or intensive

Recall the chemistry is the examine of matter, the properties, the transforms that issue undergoes and the energy connected with this changes. In this chapter, we’ll take a closer look in ~ matter and also energy and how they space related.

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When issue undergoes change, the process is regularly accompanied by a adjust in energy — heat, light, sound, kinetic energy of moving matter, etc… If heat is evolved throughout a change (is released) the change is exothermic. If heat is needs to it is in supplied, the adjust is endothermic.

An important distinction, is that heat is energy that flows as result of a temperature difference, if temperature is a measure of the average kinetic energy of the molecules in a substance. The faster they move, the “hotter” that is.

The features that permit us to distinguish one problem from an additional are referred to as properties. A physical property is a properties of matter that is not connected with a change in its chemistry composition. Familiar examples of physics properties include density, color, hardness, melting and also boiling points, and also electrical conductivity. We have the right to observe part physical properties, such together density and color, without an altering the physics state that the issue observed. Other physical properties, such as the melting temperature of stole or the freeze temperature the water, deserve to only be observed as issue undergoes a physical change. A physical change is a readjust in the state (Figure 1) or nature of issue without any kind of accompanying adjust in its chemistry composition (the identities the the substances had in the matter), such as dissolution and dilution.

Figure 1. The different phase transforms that matter deserve to undergo.

We observe a physical change when wax melts, once sugar disappear in coffee, and also when heavy steam condenses into liquid water (Figure 2). Other examples of physical alters include magnetizing and also demagnetizing metals (as is done with usual antitheft defense tags) and also grinding solids into powders (which can sometimes yield noticeable alters in color). In every of these examples, over there is a change in the physical state, form, or nature of the substance, yet no adjust in its chemical composition.

Figure 2. (a) Wax undergoes a physical adjust when heavy wax is heated and also forms liquid wax. (b) steam condensing inside a food preparation pot is a physical change, as water vapor is readjusted into liquid water. (credit a: modification of occupational by “95jb14”/Wikimedia Commons; credit transaction b: modification of occupational by “mjneuby”/Flickr)

The change of one type of matter into another type (or the i can not qualify to change) is a chemical property. Examples of chemical properties include flammability, toxicity, acidity, reactivity (many types), and heat of combustion. Iron, because that example, combines through oxygen in the presence of water to form rust; chromium does no oxidize (Figure 3). Nitroglycerin is very dangerous because it explodes easily; neon poses almost no hazard due to the fact that it is really unreactive.

Figure 3. (a) among the chemistry properties of iron is the it rusts; (b) one of the chemical properties of chromium is the it go not. (credit a: alteration of job-related by Tony Hisgett; credit transaction b: alteration of occupational by “Atoma”/Wikimedia Commons)

To recognize a chemical property, us look because that a chemical change. A chemical change constantly produces one or much more types of issue that differ from the matter present before the change. The development of rust is a chemical readjust because rust is a different kind of matter than the iron, oxygen, and water present before the rust formed. The explode of nitroglycerin is a chemical change because the gases created are really different kinds of matter from the original substance. Other examples of chemical alters include reactions that are performed in a rap (such together copper reacting v nitric acid), all creates of burning (burning), and also food being cooked, digested, or rotting (Figure 4).

Figure 4. (a) Copper and nitric mountain undergo a chemical change to form copper nitrate and also brown, gas nitrogen dioxide. (b) during the burning of a match, cellulose in the match and also oxygen native the air experience a chemical adjust to kind carbon dioxide and also water vapor. (c) food preparation red meat reasons a number of chemical changes, including the oxidation of iron in myoglobin that outcomes in the acquainted red-to-brown shade change. (d) A banana turning brown is a chemical adjust as new, darker (and less tasty) building material form. (credit b: modification of work by Jeff Turner; credit c: change of occupational by Gloria Cabada-Leman; credit transaction d: change of occupational by Roberto Verzo)

Example 1

Classify each of the following as either a physical property, or a chemical property:a) The boiling point of water is 100oCb) Oxygen is a gasc) sugar ferments to type alcohol


a) return this property explains a change, this readjust does not involve a readjust in substance. H2O continues to be H2O regardless of what state that is in. Thus, this is a physical property.

b) This is an innate property, and also is as such a physical property.

c) This property requires a adjust in substance, from street to alcohol. This is a chemistry property.

Test Yourself

Classify every of the adhering to as one of two people a physical property, or a chemical property:a) This web page is white b) Wood burns c) Milk curdles if left out


a) physical residential or commercial property b) chemical residential property c) chemical property

Properties the matter autumn into one of two categories. If the residential or commercial property depends on the amount of matter present, that is an extensive property. The mass and volume the a substance are instances of considerable properties; because that instance, a gallon that milk has a bigger mass and also volume than a cup the milk. The worth of substantial property is directly proportional come the quantity of issue in question. If the property of a sample of matter does not depend on the quantity of matter present, it is one intensive property. Temperature is an example of an extensive property. If the gallon and cup the milk space each at 20 °C (room temperature), once they space combined, the temperature remains at 20 °C. As an additional example, think about the distinct but related properties of heat and also temperature. A fall of hot cooking oil spattered on her arm reasons brief, young discomfort, vice versa, a pot of hot oil yields major burns. Both the drop and the pot of oil space at the very same temperature (an extensive property), however the pot plainly contains much much more heat (extensive property).

Example 2

Classify each of the adhering to as either a physical change, or a chemical change:a) steam condensing top top a shower head mirrorb) Iron forming rustc) an antacid tablet computer fizzes as soon as it come in contact with stomach acidd) Salt dissolves in water


a) The heavy steam is water vapor, and also when the condenses, it creates liquid water top top the mirror.This is a physical change.

b) iron reacts with the oxygen in air, developing an steel oxide, i beg your pardon is rust.This is a chemistry change.

c) The fizzing in the water is the release of carbon dioxide gas as soon as it comes in contact with acid. This is a chemistry change.

d) dissolve is considered a physics change. Also though the binding of salt space pulled apart as soon as dissolved, they execute not type new bonds, or a brand-new substance. If girlfriend evaporate the water, salt will certainly remain.

Test Yourself

Classify each of the complying with as one of two people a physical change, or a chemical change:a) A rubber tape stretches as soon as you pull itb) Acetone clears nail polishc) Copper is melted at high temperaturesd) Silver metal tarnishes end time


a) physical readjust b) physical readjust (dissolving)c) physical change d) chemistry change

Example 3

Describe each process as a physical readjust or a chemistry change.

a) Water in the air turns right into snow.

b) A who hair is cut.

c) Bread dough becomes fresh bread in one oven.


a) since the water is going indigenous a gas phase to a hard phase, this is a physical change.

b) Your lengthy hair is gift shortened. This is a physical change.

c) because of the oven’s temperature, chemical alters are emerging in the bread dough to do fresh bread. These room chemical changes. (In fact, a many of food preparation involves chemistry changes.)

Test Yourself

Identify each procedure as a physical readjust or a chemistry change.

a) A fire is raging in a fireplace.

b) Water is warmed to make a cup the coffee.


a) chemical readjust b) physics change

Hazard Diamond

You may have actually seen the symbol presented in number 5 on containers of chemicals in a laboratory or workplace. Sometimes dubbed a “fire diamond” or “hazard diamond,” this chemical risk diamond provides an useful information that briefly summarizes the various dangers of which come be mindful when working through a specific substance.

Figure 5. The nationwide Fire Protection firm (NFPA) peril diamond summarizes the major hazards that a chemical substance.

The nationwide Fire Protection firm (NFPA) 704 risk Identification device was occurred by NFPA to administer safety details about details substances. The device details flammability, reactivity, health, and other hazards. In ~ the as whole diamond symbol, the optimal (red) diamond mentions the level of fire hazard (temperature range for flash point). The blue (left) diamond indicates the level of wellness hazard. The yellow (right) diamond defines reactivity hazards, such as how readily the substance will undergo detonation or a violent chemical change. The white (bottom) diamond clues out one-of-a-kind hazards, such together if the is one oxidizer (which enables the substance to burn in the absence of air/oxygen), undergoes an unexplained or dangerous reaction with water, is corrosive, acidic, alkaline, a biological hazard, radioactive, and so on. Each peril is rated top top a scale from 0 come 4, through 0 being no hazard and also 4 being very hazardous.

Decomposition that Water / manufacturing of Hydrogen

Water consists of the facets hydrogen and oxygen combined in a 2 to 1 ratio. Water deserve to undergo a chemical readjust involving the water molecules being broken down right into hydrogen and oxygen gases by the enhancement of energy. One method to carry out this is with a battery or strength supply, as presented in (Figure 6).

Figure 6. The decomposition the water is shown at the macroscopic, microscopic, and symbolic levels. The battery gives an electric present (microscopic) that decomposes water. In ~ the macroscopic level, the fluid separates into the gases hydrogen (on the left) and oxygen (on the right). Symbolically, this readjust is gift by showing exactly how liquid H2O separates right into H2 and also O2 gases.

The failure of water requires a rearrangement of the atom in water molecules into different molecules, each created of two hydrogen atoms and two oxygen atoms, respectively. Two water molecules kind one oxygen molecule and also two hydrogen molecules. The depiction for what occurs, 2 extH_2 extO(l) ightarrow 2 extH_2(g) + extO_2(g), will be discover in an ext depth in later on chapters.

The 2 gases created have distinctly different properties. Oxygen is not flammable yet is required for burning of a fuel, and hydrogen is very flammable and a potent energy source. How might this expertise be used in ours world? One application entails research into much more fuel-efficient transportation. Fuel-cell vehicles (FCV) operation on hydrogen rather of gasoline (Figure 7). They are much more efficient 보다 vehicles v internal combustion engines, room nonpolluting, and reduce greenhouse gas emissions, making us much less dependent on fossil fuels. FCVs room not yet financially viable, however, and also current hydrogen production depends on herbal gas. If us can develop a process to economically decompose water, or produce hydrogen in another environmentally sound way, FCVs may be the way of the future.

Figure 7. A fuel cell generates electrical energy from hydrogen and oxygen via one electrochemical process and produces only water together the rubbish product.

While many facets differ drastically in their chemical and physical properties, some aspects have similar properties. We deserve to identify sets of facets that exhibit typical behaviors. Because that example, many facets conduct heat and electricity well, whereas rather are poor conductors. These properties have the right to be provided to type the facets into three classes: metals (elements the conduct well), nonmetals (elements that conduct poorly), and metalloids (elements that have actually properties the both metals and nonmetals).

The regular table is a table of facets that places aspects with comparable properties close together (Figure 6). You will learn an ext about the regular table as you continue your study of chemistry.

Figure 6. The periodic table reflects how elements may be grouped according to certain comparable properties. Note the background shade denotes even if it is an aspect is a metal, metalloid, or nonmetal, whereas the aspect symbol shade indicates whether it is a solid, liquid, or gas.

Key Concepts and also Summary

All building materials have distinctive physical and chemical properties, and also may undergo physical or chemistry changes. Physical properties, such together hardness and also boiling point, and physical changes, such together melting or freezing, execute not show off a readjust in the ingredient of matter. Chemical properties, such flammability and also acidity, and chemical changes, such as rusting, involve production of matter that different from that present beforehand.

Measurable properties fall into among two categories. Considerable properties rely on the quantity of matter present, for example, the fixed of gold. Intensive properties perform not depend on the quantity of issue present, because that example, the density of gold. Warm is an example of comprehensive property, and also temperature is an instance of an extensive property.


1. Classify each of the following transforms as physics or chemical:

a) condensation the steam

b) burning of gasoline

c) souring that milk

d) dissolve of sugar in water

e) melt of gold

2. The volume that a sample that oxygen gas readjusted from 10 mL come 11 mL together the temperature changed. Is this a chemistry or physical change?

3. Define the difference between extensive properties and intensive properties.

4. The thickness (d) the a problem is an intensive property that is defined as the ratio of its mass (m) come its volume (V).

extdensity= frac extmass extvolume extd = frac extm extV

Considering the mass and also volume are both comprehensive properties, describe why your ratio, density, is intensive.

5. Does each statement stand for a physical residential or commercial property or a chemistry property?

a) Sulfur is yellow.

b) steel wool burns once ignited by a flame.

c) A gallon that milk weighs end eight pounds.

6. Does every statement represent a physical home or a chemistry property?

a) A pile of leaves gradually rots in the backyard.

b) In the existence of oxygen, hydrogen can communicate to do water.

c) Gold deserve to be stretched into really thin wires.

7. Does each statement represent a physical adjust or a chemistry change?

a) Water boils and becomes steam.

b) Food is converted right into usable form by the cradle system.

c) The alcohol in numerous thermometers freezes at about −40 levels Fahrenheit.

8. Does each statement represent a physical readjust or a chemical change?

a) Graphite, a kind of element carbon, have the right to be turned into diamond, another kind of carbon, at very high temperatures and also pressures.

b) The elements sodium and chlorine come together to do a new substance dubbed sodium chloride.


1. A) physical; b) chemical; c) chemical; d) physical; e) physical

2. Physical

3. The value of an extensive property counts upon the amount of issue being considered, vice versa, the value of an intensive property is the very same regardless that the amount of issue being considered.

4. Being substantial properties, both mass and also volume are directly proportional to the lot of problem under study. Separating one considerable property by an additional will in impact “cancel” this dependency on amount, yielding a ratio that is elevation of lot (an intensive property).

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5. a) physical residential or commercial property b) chemical home c) physics property

6. a) chemical residential property b) chemical property c) physical property


chemical change: change creating a various kind of matter from the initial kind of matter

chemical property: behavior that is regarded the change of one sort of issue into one more kind that matter

endothermic: if warmth is requirements to be supplied, because that a change to occur

energy: the capacity to perform “work”— that is, because that a pressure to action on something and push part distance

exothermic: if heat is released throughout a change

extensive property: property the a substance that depends on the quantity of the substance

intensive property: property that a substance the is elevation of the amount of the substance

physical change: change in the state or nature of matter that does no involve a readjust in its chemical composition

physical property: characteristic of issue that is not linked with any change in its chemistry composition


CHEM 1114 - advent to Chemistry by Shirley Wacowich-Sgarbi is licensed under a an imaginative Commons Attribution-NonCommercial-ShareAlike 4.0 worldwide License, other than where otherwise noted.