The Three States of Matter

The three states of matter can be interconverted without changing the composition of the substance. Upon heating, a solid (for example, ice) will melt to form a liquid (water). (The temperature at which this transition occurs is called the melting point.) Further heating will convert the liquid into a gas. (This conversion takes place at the boiling point of the liquid.) On the other hand, cooling a gas will cause it to condense into a liquid. When the liquid is cooled further, it will freeze into the solid form. 

An ice cube is placed in a closed container. On healing, the ice cube first melts and the water then boils to form steam. Which of the following stat ents is true  

The following sample problem provides practice identifying these types of changes. 

SAMPLE PROBLEM 1.1 Distinguishing Between Physical and Chemical Change 

Problem Decide whether each of the following processes is primarily a physical or a chemical change, and explain briefly  

Plan The basic question we ask to decide whether a change is chemical or physical is, Does the substance change composition or just change form  

Solution (a) Frost forming is a physical change the drop in temperature changes water vapor (gaseous water) in humid air to ice crystals (solid water). 

Animation The Three States of Matter Online Learning Center 

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FIGURE A.l A molecular representation of the three states of matter. In each case, the spheres represent particles that may be atoms, molecules, or ions, (a) In a solid, the particles are packed tightly together, but continue to oscillate, (b) In a liquid, the particles are in contact, but have enough energy to move past one another, (c) In a gas, the particles are far apart, move almost completely freely, and are in ceaseless random motion. 

The next concept which we wish to examine is that of the differences between the three states of matter, gases, liquids and solids. In this case, we will find very significant differences in their energy content, namely that the gaseous form is the most energetic while the solid has the least energy. 

Note that the diagram has three general areas corresponding to the three states of matter solid, liquid, and gas. The line from A to C represents the change in vapor pressure of the solid with temperature for the sublimation (going directly from a solid to a gas without first becoming a liquid) equilibrium. The A to... 

Summary Of the three states of matter—gases, liquids, and solids—gases are probably the best understood and have the best descriptive model. 

Gases are one of the three states of matter, along with solids and liquids. They re much less structured than the other two gases easily change both their volume and shape. A gas will not only flow like a liquid, it will also expand to fill a container. 

Learning the characteristics of the three states of matter solid, liquid, and gas... 

Nearly every substance can exist as a solid, a liquid, or a gas. These are the three common states of matter. Whether a substance is a solid or a liquid or a gas depends on its temperature and the pressure placed on it. At room temperature (about 22° C) and at the normal pressure exerted by the atmosphere, water exists as a liquid, which can flow from one container to another. But if its temperature is lowered to about —10° C, liquid water freezes to solid ice. Going the opposite direction in temperature and at this same pressure, water changes to a gas when the temperature exceeds 100° C. Changes in state can also occur by changing the pressure while holding temperature constant. The relationship between temperature and pressure and the three states of matter is easier to see when displayed in a phase diagram. Because phase diagrams provide so much information, they are known for thousands of substances. 

The macroscopic properties of the three states of matter can be modeled as ensembles of molecules, and their interactions are described by intermolecular potentials or force fields. These theories lead to the understanding of properties such as the thermodynamic and transport properties, vapor pressure, and critical constants. The ideal gas is characterized by a group of molecules that are hard spheres far apart, and they exert forces on each other only during brief periods of collisions. The real gases experience intermolecular forces, such as the van der Waals forces, so that molecules exert forces on each other even when they are not in collision. The liquids and solids are characterized by molecules that are constantly in contact and exerting forces on each other. 

Although atoms are not mentioned in the brief prospectus, chemical atomism is the basis of Daltons New System, in which the third chapter clearly tends to place the whole science of Chemistry upon a new, and more simple basis. It is interesting that the new atomic chemistry does not occur in Daltons book until the third chapter, which occupies less than ten percent of Part I. Chapter One is chiefly focused on heat and gases, and Chapter Two on the three states of matter. As we have already seen, the third chapter presents his method for determining the relative weights of the atoms, with the promise that from... 

Chemistry is about what matter is like and how it behaves, and our explanations and predictions of its behaviour. What is matter This word is used to cover all the substances and materials from which the physical universe is composed. There are many millions of different substances known, and all of them can be categorised as solids, liquids or gases (Figure 1.1). These are what we call the three states of matter. 

The kinetic theory can be used as a scientific model to explain how the arrangement of particles relates to the properties of the three states of matter. 

Solids, liquids and gases The three states of matter to which all substances belong. 

The following diagram shows the three states of matter and how they can be interchanged. 

Solids, liquids, and gases are the three states of matter traditionally recognized in chemistry. But more recently, some scientists have argued that other states of matter exist as well. Each new state of matter is some variation of the original three, but some states are more readily accepted by scientists than others. This chapter looks at a handful of other states of matter. 

Of the three states of matter (solid, liquid, and gas), only gases have radically changing distances between molecules. When the distances between the molecules of a gas are different than what is found at STP (Standard Temperature and Pressure), we have either a positive or negative pressure (compared to atmospheric). 

States of matter The three states of matter are gas, liquid, and solid. 

Of the three states of matter, solids possess the most structural diversity. Whereas gases and liquids consist of discrete molecules that are randomly distributed due to thermal motion, solids consist of molecules, atoms, or ions that are statically positioned. To fully understand the properties of solid materials, one must have a thorough knowledge of the structural interactions between the subunit atoms, ions, and molecules. This chapter will outline the various types of solids, including structural classifications and nomenclature for both crystalline and amorphous solids. The material in this key chapter will set the groundwork for the rest of this textbook, which describes a variety of materials classes. 

You have only to think about water to appreciate how different the three states of matter are. Flying, swimming, and ice skating are all done in contact with water in its various forms. Clearly, the arrangements of the water molecules must be significantly different in its gas, liquid, and solid forms. 

Now that we have considered the general properties of the three states of matter, we can explore the processes by which matter changes state. One very familiar example of a change in state occurs when a liquid evaporates from an open container. This is clear evidence that the molecules of a liquid can escape from the liquid s surface and form a gas. Called vaporization, or evaporation, this process is endothermic, because energy is required to overcome the relatively strong intermolecular forces in the liquid. The energy required to vaporize 1 mole of a liquid at a pressure of 1 atm is called the standard heat of vaporization, or the standard enthalpy of vaporization, and is usually symbolized as AH°ap. 

Figure 1-2 A comparison of some physical properties of the three states of matter. (Left) Iodine, a solid element. (Center) Bromine, a liquid element. (Right) Chlorine, a gaseous element.

Figure 1-3 Physical changes that occur among the three states of matter. Sublimation is the conversion of a sohd directly to a gas without passing through the liquid state the reverse of that process is called deposition. The changes shown in hlue are endothermic (ahsorh heat) those shown in red are exothermic (release heat). Water is a substance that is familiar to us in all three physical states. The molecules are close together in the solid and the liquid but far apart in the gas. The molecules in the solid are relatively fixed in position, but those in the liquid and gas can flow around each other.

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