Q of the Day At 27ºC a sample exerts a pressure of 4 atms., what is the Celsius temperature if the pressure increases to 8 atms.? Whose law: Pressure-volume relationship? What is the temperature at STP? The ideal gas applies when…? Day 4 11-17 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

page 474 #s 40-41, 43, 45 - Go over! Assignment Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Chapter 13 States of Matter 13.2 The Nature of Liquids 13.1 The Nature of Gases 13.2 The Nature of Liquids 13.3 The Nature of Solids 13.4 Changes of State Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Substances that can flow are referred to as fluids. A Model for Liquids Substances that can flow are referred to as fluids. Both liquids and gases can flow. The ability of gases and liquids to flow allows them to conform to the shape of their containers. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Gases and liquids have a key difference between them. A Model for Liquids Gases and liquids have a key difference between them. According to kinetic theory, there are no attractions between the particles in a gas. The particles in a liquid are attracted to each other. These intermolecular attractions keep the particles in a liquid close together, which is why liquids have a definite volume. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Liquids are much more dense than gases. A Model for Liquids Liquids are much more dense than gases. Increasing the pressure on a liquid has hardly any effect on its volume. The same is true for solids. Liquids and solids are known as condensed states of matter. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

The conversion of a liquid to a gas or vapor is called vaporization. Evaporation The conversion of a liquid to a gas or vapor is called vaporization. When this conversion occurs at the surface of a liquid that is not boiling, the process is called evaporation. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Evaporation The process of evaporation has a different outcome in an open system, such as a lake or an open container, than in a closed system, such as a sealed container. In a closed system, the molecules collect as a vapor above the liquid. Some condense back into a liquid. In an open system, molecules that evaporate can escape from the system. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

A liquid evaporates faster when heated. Evaporation A liquid evaporates faster when heated. A liquid evaporates when the particles have enough kinetic energy to overcome the attractive forces keeping them in the liquid state. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Evaporation As evaporation occurs, the particles with the highest kinetic energy tend to escape first. As evaporation takes place, the liquid’s temperature decreases. Evaporation is a cooling process. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

You can observe the effects of evaporative cooling on hot days. Evaporation You can observe the effects of evaporative cooling on hot days. When you perspire, water molecules in your perspiration absorb heat from your body and evaporate from the skin’s surface. This evaporation leaves the remaining perspiration cooler. The perspiration that remains cools you further by absorbing more body heat. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Vapor Pressure The evaporation of a liquid in a closed system vs. in an open system. When a partially filled container of liquid is sealed, some of the particles at the surface of the liquid vaporize. These particles collide with the walls of the sealed container, producing pressure. A measure of the force exerted by a gas above a liquid is called vapor pressure. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Vapor Pressure Over time, the number of particles entering the vapor increases and some of the particles condense and return to the liquid state. Liquid Vapor (gas) evaporation condensation Eventually, the number of particles condensing will equal the number of particles vaporizing. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Vapor Pressure In a system at constant vapor pressure, a dynamic equilibrium exists between the vapor and the liquid. The system is in equilibrium because the rate of evaporation of liquid equals the rate of condensation of vapor. the particles in the system continue to evaporate and condense, but no net change occurs in the number of particles in the liquid or vapor. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Vapor Pressure and Temperature Change An increase in the temperature of a contained liquid _____________ the vapor pressure. increases Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Vapor Pressure (in kPa) of Three Substances at Different Temperatures Interpret Data The vapor pressure data indicates how volatile a given liquid is, or how easily it evaporates. Vapor Pressure (in kPa) of Three Substances at Different Temperatures Substance 0°C 20°C 40°C 60°C 80°C 100°C Water 0.61 2.33 7.37 19.92 47.34 101.33 Ethanol 1.63 5.85 18.04 47.02 108.34 225.75 Diethyl ether 24.70 58.96 122.80 230.65 399.11 647.87 Tell me about their boiling points. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Boiling Point When a liquid is heated to a temperature at which particles throughout the liquid have enough kinetic energy to vaporize, the liquid begins to boil. The boiling point (bp) is the temperature at which the vapor pressure of the liquid is just equal to the external pressure on the liquid. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Boiling Point and Pressure Changes Because a liquid boils when its vapor pressure is equal to the external pressure, liquids don’t always boil at the same temperature. Because atmospheric pressure is lower at higher altitudes, boiling points ______________ at higher altitudes. decrease Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

In a sealed gas-liquid system at a constant temperature, eventually A. there will be no more evaporation. B. the rate of condensation decreases to zero. C. the rate of condensation exceeds the rate of evaporation. D. the rate of evaporation equals the rate of condensation. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

In a sealed gas-liquid system at a constant temperature, eventually A. there will be no more evaporation. B. the rate of condensation decreases to zero. C. the rate of condensation exceeds the rate of evaporation. D. the rate of evaporation equals the rate of condensation. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Is the boiling point of water at the top of Mount McKinley (the highest point in North America) higher or lower than it is in Death Valley (the lowest point in North America)? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

vaporization: the conversion of a liquid to a gas or a vapor Glossary Terms vaporization: the conversion of a liquid to a gas or a vapor evaporation: vaporization that occurs at the surface of a liquid that is not boiling vapor pressure: a measure of the force exerted by a gas above a liquid in a sealed container; a dynamic equilibrium exists between the vapor and the liquid Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Glossary Terms boiling point: the temperature at which the vapor pressure of a liquid is just equal to the external pressure on the liquid Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

REVIEW HOMEWORK Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Chapter 13 States of Matter 13.3 The Nature of Solids 13.1 The Nature of Gases 13.2 The Nature of Liquids 13.3 The Nature of Solids 13.4 Changes of State Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

A Model for Solids The general properties of solids reflect the orderly arrangement of their particles and the fixed locations of their particles. In most solids, the atoms, ions, or molecules are packed tightly together. Solids are dense and not easy to compress. Solids do not flow. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

A Model for Solids When you heat a solid, its particles vibrate more rapidly as their kinetic energy increases. The melting point (mp) is the temperature at which a solid changes into a liquid. At this temperature, the disruptive vibrations of the particles are strong enough to overcome the attractions that hold them in fixed positions. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

A Model for Solids The freezing point (fp) = temperature at which a liquid changes into a solid. The melting point = the freezing point At that temperature, liquid and solid phases are in equilibrium. Solid Liquid melting freezing Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Molecular solids have relatively low melting points. A Model for Solids In general, ionic solids have high melting points because relatively strong forces hold them together. Sodium chloride, an ionic compound, has a rather high melting point of 801°C. Molecular solids have relatively low melting points. Hydrogen chloride, a molecular compound, melts at –112°C. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Allotropes Some substances can exist in more than one form. Diamond is one crystalline form of carbon. A different form of carbon is graphite. In 1985, a third crystalline form of carbon was discovered. This form is called buckminsterfullerene. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Allotropes In diamond, each carbon atom in the interior of the diamond is strongly bonded to four others. The array is rigid and compact. In graphite, the carbon atoms are linked in widely spaced layers of hexagonal arrays. In buckminster-fullerene, 60 carbon atoms form a hollow sphere. The carbons are arranged in penta-gons and hexagons. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Allotropes The physical properties of diamond, graphite, and fullerenes are quite different. Diamond has a high density and is very hard. Graphite has a relatively low density and is soft and slippery. The hollow cages in fullerenes give them strength and rigidity. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Allotropes Diamond, graphite, and fullerenes are crystalline allotropes of carbon. Allotropes are two or more different molecular forms of the same element in the same physical state. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Allotropes Diamond, graphite, and fullerenes are crystalline allotropes of carbon. Allotropes are two or more different molecular forms of the same element in the same physical state. Although allotropes are composed of atoms of the same element, they have different properties because their structures are different. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Allotropes Only a few elements have allotropes. In addition to carbon, these include phosphorus, sulfur, oxygen (O2 and O3), boron, and antimony. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

CHEMISTRY & YOU What structural properties make fullerene nanotubes the strongest material in the world? Each carbon atom is covalently bonded to three other carbon atoms. The structure creates a spherical cage or cylindrical tube. This shape allows force to be distributed evenly across the surface so that the entire structure can withstand great force and is extremely strong. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Non-Crystalline Solids Not all solids are crystalline in form; some solids are amorphous. An amorphous solid lacks an ordered internal structure. Rubber, plastic, and asphalt are amorphous solids. Their atoms are randomly arranged. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Crystal Structure and Unit Cells Non-Crystalline Solids Other examples of amorphous solids are glasses. A glass is a transparent fusion product of inorganic substances that have cooled to a rigid state without crystallizing. Glasses are sometimes called supercooled liquids. The irregular internal structures are intermediate between those of a crystalline solid and those of a free-flowing liquid. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

What is the difference between an amorphous solid and a crystalline solid? Particles in a crystalline solid are arranged in an orderly, repeating pattern or lattice. Particles in an amorphous solid are arranged randomly. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Key Concepts The general properties of solids reflect the orderly arrangement and the fixed locations of their particles. The shape of a crystal reflects the arrangement of the particles within the solid. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Glossary Terms crystal: a solid in which the atoms, ions, or molecules are arranged in an orderly, repeating, three-dimensional pattern called a crystal lattice allotrope: one of two or more different molecular forms of an element in the same physical state; oxygen (O2) and ozone (O3) are allotropes of the element oxygen Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Glossary Terms amorphous solid: describes a solid that lacks an ordered internal structure; denotes a random arrangement of atoms glass: a transparent fusion product of inorganic substances that have cooled to a rigid state without crystallizing Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

END OF 13.3 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Quick Talk PV = nRT Boyle’s Law Absolute zero Ideal Gas Charles’ Law Avogadro’s Law Pascal Precipitate Synthesis reaction Boyle’s Law Ideal Gas Kinetic Energy Mole Standard Temperature and Pressure Attract Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.