Physics
Changes of state
Changes of state refer to the physical transformations that matter undergoes when transitioning between solid, liquid, and gas states. These changes occur due to variations in temperature and pressure. For example, when a solid ice cube melts into liquid water, it undergoes a change of state from solid to liquid due to an increase in temperature.
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11 Key excerpts on "Changes of state"
eBook - PDF- Douglas P. Heller, Carl H. Snyder(Authors)
- 2015(Publication Date)
- Wiley(Publisher)
When you heat a solid, though, its chemical particles absorb energy. When the temperature of the solid reaches intermolecular forces Attractive forces that exist between molecules in close proximity. Distinguishing states of matter • Figure 6.1 All common objects are either a solid, a liquid, or a gas. Some substances, like water, can be in any state, depending on factors such as temperature. Ask Yourself Which of the three common states of matter—solids, liquids, or gases—(a) maintain their own shapes, no matter what container holds them? (b) maintain their own volumes, no matter what container holds them? a. Solid - - retains own shape b. Liquid - - adopts shape of container c. Gas - adopts volume and shape of container fixed volume fixed volume 165 move about freely within the bulk of the material, we observe that the solid melts to a liquid (Figure 6.2). Melting and other changes in state are examples of a physical change. its melting point, the movements of its particles become sufficiently vigorous to tear them away from their neighbors and out of their fixed positions. As they begin to What happens when solids melt • Figure 6.2 When we heat a solid to its melting point, individual particles, such as molecules, gain enough energy to break out of their fixed positions. This is what happens when ice melts to form water. WHAT A CHEMIST SEES States of Matter at the Molecular Level Water is found in its three physical states in this image of geothermal activity in Yellowstone National Park. In each state of matter, water molecules differ in their arrangements and movements. melting point The temperature at which a solid is transformed into a liquid. physical change A transformation of matter that occurs without any change in chemical composition. Gas In water vapor, water molecules move about at high speeds and at relatively large distances from one another.
- Wallace Brey(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
One States of Matter The differences we observe in the characteristics of the three states of matter—gas, liquid, and solid—depend upon the variation in the condi-tion of aggregation of the molecules of which the matter is composed. In this chapter some of the principles governing transformation of one state of matter into another are considered. Structural models for gases and liquids are discussed, and the relationships between the macro-scopic properties of these phases and the behavior and properties of individual molecules are examined, particularly from the viewpoint of the influence of forces between molecules. 1-1 MOLECULAR PICTURE OF MATTER From the properties of the gaseous state of matter, scientists have de-duced a model in which the molecules are relatively far apart and are free to move almost independently of one another. This picture is em-bodied in the kinetic theory, which describes the molecules of a gas as separated particles in continuous motion. Each molecule travels in a straight line until it collides with another molecule or strikes the wall of the vessel in which it is confined. W h e n the vessel is enlarged, mo-lecular motion causes the gas to spread throughout all the newly acces-sible space; the application of external pressure, however, readily compresses the gas into a smaller volume, for the molecules have a relatively large amount of empty space between them. In a liquid, the molecules are more restricted in their movement: They are able to roll past one another so that the liquid can flow, but it is only with considerable difficulty that they detach themselves from intimate association with other molecules in the bulk of the liquid, as they must do if the liquid is to be vaporized. In a solid, each molecule has a definitely assigned average position about which it vibrates; movement of the molecule away from its own small compartment, 2 ONE STATES OF MATTER formed by neighboring molecules, is a comparatively unusual event.
eBook - PDFThermodynamics
Fundamentals and Engineering Applications
- William C. Reynolds, Piero Colonna(Authors)
- 2018(Publication Date)
- Cambridge University Press(Publisher)
3 Properties and States CONTENTS 3.1 Concepts of Property and State 32 3.2 Pressure 34 3.3 Temperature 35 3.4 The State Principle 36 3.5 States of a Simple Compressible Substance 38 3.6 Thermodynamic Property Data 40 3.7 Derivative Properties 43 3.8 The Ideal (or Perfect) Gas 44 3.9 A Microscopic Model for the Ideal Gas 45 3.10 Extensions to Polyatomic Ideal Gases 47 Exercises 48 The examples of energy analysis in Chapter 2 show that, in order to obtain quantitative results from energy balances, we need to evaluate the thermodynamic properties of fluids at the relevant states of the processes. We used the ideal gas model with constant specific heat to calculate pressure, temperature, specific volume, and internal energy, an anticipation of what is explained and generalized in this chapter. In order to treat problems in which the working fluid can be a liquid, or a vapor, and in all cases in which the fluid does not obey the ideal gas law, we have to learn how we can obtain this information first from tables and charts, then using software. Before we master how to use these tools, we must learn in a more systematic way what thermodynamic properties and states of fluids are, understand the relations and transitions between the various possible states of matter, and how they can be visualized on appropriate diagrams, revealing their complex interaction. 3.1 Concepts of Property and State Properties A property is any characteristic or attribute of mat-ter that can be quantitatively evaluated. Volume, mass, density, energy, charge, temperature, pressure, magnetic dipole moment, electric dipole moment, internal energy, momentum, surface tension, veloc-ity, entropy, viscosity, and color are all properties. Work and heat are not properties because they are not something that matter has , but instead are amounts of energy transfer to or from matter. States The state of a system is its condition as described by the values of all of its properties.
- John Reisel(Author)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
69 C H A P T E R 3 Thermodynamic Properties and Equations of State Learning Objectives Upon completion of Chapter 3, you will be able to 3.1 Describe the structure of phase diagrams and the associated terminology; 3.2 Express the state postulate; 3.3 Summarize the relationship between the two specific heats and the properties of specific enthalpy and specific internal energy; 3.4 Apply the equations of state for ideal gases and incompressible substances, and employ more complex equations of state for real gases; 3.5 Compute thermodynamic properties for substances near phase-change regions, such as water and the refrigerants. 3.1 INTRODUCTION Designing and analyzing thermodynamic systems requires being able to describe the state of the substance in the system. As discussed in Chapter 1, we describe the state of a substance by identifying various properties of the substance. Not all properties must be measured for a substance to specify its state. As we will see in this chapter, the state of a pure substance can often be adequately described by two independent intensive properties; all other properties can then be derived through equations of state. In this chapter, we will first explore a method to visually illustrate the state of a substance and the processes it undergoes, and then learn how to use equations of state to find all the needed properties of a well-defined system. 3.2 PHASE DIAGRAMS As described in Chapter 1, matter exists in different phases, and the phases that we are most concerned with are solid, liquid, and gas (or vapor). At a particular set of conditions, a sub- stance at equilibrium will always exist in the same phase. So, at a pressure of 101 kPa and a temperature of 208C, water at equilibrium is always in liquid form. Similarly, at the same Copyright 2022 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
eBook - PDFEngineering Materials Science
Properties, Uses, Degradation, Remediation
- H McArthur, D Spalding(Authors)
- 2004(Publication Date)
- Woodhead Publishing(Publisher)
2 STATES OF MATTER AND PHYSICAL CONSTANTS 2.1 INTRODUCTION There are three states of matter, a gas or vapour, a liquid (the most common one being water) and a solid (which may be amorphous or crystalline). These three states (or phases) are shown by water as the solid ice, the liquid water and as the vapour steam. In this Chapter we focus on water, as this compound is responsible for a wide range of building defects and deterioration mechanisms (Chapters Sand 6). 2.2GASES Gas molecules exlubit constant translocational movement (visualised as billiard balls colliding) and fill the available volume. Gas molecules are modelled as having principally translocational kinetic energy and a relatively small amount ofvibrational kinetic energy (movement which stretches the interatomic bonds, e.g, Cl-Cl, 0-0, etc.). An increase in temperature increases the translocational kinetic energy to a greater extent than the vibrational kinetic energy. A decrease in temperature results in the molecules of a gas coming into closer proximity, so that bonding can occur and the gas (water vapour) condenses to form a liquid. 2.2.1 Ideal Gas Laws If one mole of a gas is confined in volume V at temperature T, the pressure exerted by the gas, p, obeys the relationship pV =RT, where R is the universal gas constant(= 8414 J/kmol.K) and Tis absolute temperature (K). For n moles of the gas, pV = nRT, where n = m!M and mis the mass of the gas of molecular weight M. This equation is the equation of state of a perfect gas, also known as the ideal ( perfect) gas law. 2.2.2 Fundamental Kinetic Theory Equation for a Gas The kinetic energy possessed by a body by virtue of its motion is called the kinetic energy of the body. Suppose a gas molecule of mass m moving with velocity u is bought to rest in a distance s by a constant retarding force F (Figure 2.1 a). The original kinetic energy of the gas molecule is equal to Fs, and this must therefore be the work done in bringing the molecule to rest.
eBook - PDFChemistry for Today
General, Organic, and Biochemistry
- Spencer Seager, Michael Slabaugh, Maren Hansen, , Spencer Seager, Spencer Seager, Michael Slabaugh, Maren Hansen(Authors)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 186 Chapter 6 In some instances, solids cannot be changed into liquids, or liquids into gases, by heating. The atoms making up the molecules of some solids acquire enough kinetic energy on heating to cause bonds within the molecules to break before the solid (or liquid) can change into another state. This breaking of bonds within molecules changes the composition of the original substance. When this decomposition occurs, the original substance is said to have decomposed. This is why cotton and paper, when heated, char rather than melt. 6.15 Energy and the States of Matter Learning Objective 13 Do calculations based on energy changes that accompany heating, cooling, or changing the state of a substance. A pure substance in the gaseous state contains more energy than in the liquid state, which in turn contains more energy than in the solid state. Before we look at this, note the following relationships. Kinetic energy, the energy of particle motion, is related to heat. In fact, temperature is a measurement of the average kinetic energy of the particles in a system. Potential energy, in contrast, is related to particle separation distances rather than motion. Thus, we conclude that an increase in temperature on adding heat corresponds to an increase in kinetic energy of the particles, whereas no increase in temperature on adding heat corresponds to an increase in the potential en- ergy of the particles. Now let’s look at a system composed of 1 g of ice at an initial temperature of 220°C. Heat is added at a constant rate until the ice is converted into 1 g of steam at 120°C. The atmospheric pressure is assumed to be 760 torr throughout the experiment. The changes in the system take place in several steps, as shown in Figure 6.21.
eBook - PDFConceiving Nature after Aristotle, Kant, and Hegel
The Philosopher's Guide to the Universe
- Richard Dien Winfield(Author)
- 2017(Publication Date)
- Palgrave Macmillan(Publisher)
Whether something is moist or dry would seem to be deriva- tive upon the heat it possesses and how that heat leaves it liquid or not. What is liquid, and in some respect, moist, will, if heated sufficiently, turn into air, that is take the form of a gas. If sufficiently cooled, what is liquid and moist will solidify. Although at what degree of heat these transformations occur may be contingent upon the particular other qualities a material has, all material could be said to pass through these phases or states. They are simply generic to physical matter and for that reason they are fundamental aspects of physical reality that precede in reality and conception an account of what further distinguishes physical substances from one another. 8 The Physical States of Matter 253 Once we recognize the elements to be fundamental physical states of material substance, we can rethink the process of their transforma- tion into one another. The contrariety of hot and cold will play a funda- mental role. Pressure may also be invoked to the extent that it impacts upon the energy heat must have. The contrariety of moist and dry will be secondary to the extent that the moist depends upon the liquid state, which has specific temperature (and pressure) conditions. Moreover, the regionality of the elements can be reconceived in terms of how the states of matter impact upon physical density and the gravitational interaction of physical materials. Gas and plasma will rise above more dense liquids and solids when all are subject to the gravitational attraction of some central body. The passage of one state of matter into another will then typically depend upon changes in temperature and pressure, which themselves may be tied to the self-illuminating nuclear “fire” of stars and the gravitational mechanics of solar systems.
eBook - ePub200 Science Investigations for Young Students
Practical Activities for Science 5 - 11
- Martin Wenham(Author)
- 2000(Publication Date)
- SAGE Publications Ltd(Publisher)
6States of Matter and Physical Change
6.1: Solids, liquids and gases
Most materials and objects which children encounter in everyday life are fairly obviously in one of three states of matter: solid, liquid or gas. Observing materials to find out how they are classified in this way is an essential preliminary to investigating changes between the three states and ways in which they may be brought about. The three states of matter are sometimes written or spoken about as if there were always sharp distinctions between them; but particularly between the solid and liquid states the distinction is not always clear (Activity 6.2.2 ) and even when it is, it may not appear to be (Activity 6.1.2 ).Activity 6.1.1
Distinguishing solids from liquids
Equipment and materials: A range of (unlabelled) solid objects in a variety of materials, e.g. wood, stone, rubber (elastic bands), paper, modelling clay, plastics, metals. A range of liquids in labelled screw-top jars or bottles with tops sealed on, e.g. water, vegetable oil, thick sugar syrup, PVA glue; disposable cup; dropper; plastic or metal tray.- From all the objects in front of you, pick out the bottles or jars with liquids in them. Put them on one side to look at later.
- Look at the objects which are left. Try to identify the materials of which they are made.
- Try to change the shape of these objects by bending, pulling, squashing and twisting them in your hands. Do not break any of the objects: just find out if you can make them change shape.
- Are these objects solid or liquid? (They are solid.) Are they all solid? (Yes.) Are some more solid than others?
Children may mistakenly answer ‘Yes’ to the last question because they may equate solidity with rigidity or hardness and think that soft, squashy and stretchy materials like modelling clay and elastic bands are less solid than hard materials such as metal or stone.- What properties do all these objects have which makes us call them ‘solid’?
This may need some discussion. The scientific view is that solids maintain their shape without support, although these shapes can be changed by applying forces to them. As children might put it, solids ‘have their own shape’ and ‘stand up on their own’; but there are solid materials which need further investigation to find out how they behave (Activity 6.1.2
eBook - PDFIntroductory Chemistry
An Active Learning Approach
- Mark Cracolice, Edward Peters, Mark Cracolice(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
48 Chapter 2 Matter and Energy Concept-Linking Exercises Write a brief description of the relationships among each of the following groups of terms or phrases. Answers to the Concept-Linking Exercises are given at the end of the chapter. Example: Natural sciences, physical sciences, biological sciences, chemistry, physics, botany, zoology. Solution: The natural sciences can be divided into two general catego- ries: physical sciences (the study of matter and energy) and biological sciences (the study of living organisms). Botany and zoology are bio- logical sciences. Physics and chemistry are physical sciences, although chemistry overlaps the biological sciences in the fields of biochemistry, biological chemistry, and chemical biology. 1. Matter, state of matter, kinetic molecular theory, gas, liquid, solid 2. Homogeneous, heterogeneous, pure substance, mixture 3. Element, compound, atom, molecule 4. Physical property, physical change, chemical property, chemical change 5. Conservation of mass, conservation of energy, conservation of mass and energy 6. Energy, kinetic energy, potential energy, endothermic change, exothermic change Small-Group Discussion Questions Small-Group Discussion Questions are for group work, either in class or under the guidance of a leader during a discussion section. 1. A model often is simpler than the natural phenomenon that it represents. How is this an advantage for thinking about matter? How is it a disadvantage? 2. Viscosity is defined as the resistance of a substance to flow. Explain why each state of matter either does or does not have the property of viscosity. How do you suppose viscosity occurs at the particulate level? 3. Describe as many chemical and physical changes and properties as possible that are given in, or that you can deduce from, the following: At the end of a day of hiking in the mountains, you set up camp. You gather dry sticks and logs to build a fire, and you light the fire with a match.
eBook - PDFBasic Physical Chemistry
The Route to Understanding
- E Brian Smith(Author)
- 2012(Publication Date)
- ICP(Publisher)
9 The States of Matter 9.1 Gases, liquids and solids Matter can exist in many forms but, most commonly, we identify three distinct states: gas, liquid and solid. The state with the lowest Gibbs free energy is the stable form of matter at any particular temperature. At low temperatures, the solid with the most negative energy is the most stable form. At high temperatures, the gaseous state with the maximum randomness prevails. At intermediate temperatures, the liquid state has the lowest free energy. If the Gibbs free energy is plotted against the temperature at constant pressure, since d G = V d P − S d T , the slopes of the lines are (∂G/∂T) P = − S . The gaseous phase with the highest entropy has the largest negative slope and will have the lowest free energy at high temperatures (Fig. 9.1). The solid phase with the lowest slope has the lowest free energy at low temperatures. The transition from one phase to another occurs where the lines intersect and where the free energies are equal. Then, G = 0 and H = TS , giving, at the melting point of the solid, fus S = fus H T fus and, at the boiling point of the liquid, vap S = vap H T vap . We can represent the equilibrium of the phases as a function of temperature and pressure as shown in Fig. 9.2 for the phase equilibria in water. Such diagrams are called phase diagrams . The lines represent the pressures and temperatures at which two phases are in equilibrium. The line AB represents the vapour pressure of liquid water and AC gives the vapour pressure of ice. AD is the melting curve on which the solid and liquid are at equilibrium. The point where all three curves meet, A, is called the triple point , which, for water, is at 273.16 K and 10.61 kPa (4.58 mm Hg) pressure, the only pressure and temperature at which the three phases can co-exist in equilibrium. 199 200 | Basic Physical Chemistry G T T fus T vap Solid Liquid Gas Fig.
eBook - PDF- Leo J. Malone, Theodore O. Dolter(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
p. 374 11-4.2 The measure of how rapidly a liquid flows is its viscosity. p. 375 11-4.3 When a liquid has an equilibrium vapor pressure it undergoes vaporization or evaporation. pp. 375–376 11-4.3 Gases undergo condensation to the liquid state. The solid state may undergo sublimation to the gaseous state. p. 376 11-4.4 The temperature at which the vapor pressure of a liquid equals the restraining pressure is the boiling point. The temperature at which the vapor pressure of the liquid is equal to one atmosphere is the normal boiling point. p. 377 11-5.1 A measure of the amount of energy needed to cause melting is the heat of fusion. p. 380 11-5.2 A measure of the amount of energy needed to cause vaporization is the heat of vaporization. p. 381 11-6 The heating curve of a compound traces the changes in phases and the changes in temperature of the phases. p. 384 PART B SUMMARY What Happens When Heat is Applied to a Phase or Phases Energy Temperature Relevant Thermo- Phase What Happens Change Change dynamic Equation Solid Particles move faster about K. E. T increases Sp. heat of solid fixed positions. Solid, liquid Particles break attractions P. E. T constant Heat of fusion and move past each other. Liquid Particles move faster, K. E. T increases Sp. heat of liquid which includes translational motion. Liquid, vapor Particles break final attractions. P. E. T constant Heat of as they escape to vapor vaporization Vapor Particles move faster in K. E. T increase Sp. heat of gas gaseous state. SUMMARY CHART CHAPTER 11 SYNTHESIS PROBLEM In this chapter, we have used as an example of properties and phase changes the most important liquid in our lives. That, of course, is water. In the problem that follows, we will use two compounds that are liquids at room temperature—acetone and isopropyl alcohol—as examples. Acetone (C 3 H 6 O) is a popular solvent used in the home to remove nail polish.
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