Introductory Chemistry: A Foundation FIFTH EDITION by Steven S. Zumdahl University of Illinois Copyright©2004 by Houghton Mifflin Company. All rights reserved. 1 Matter and Energy Chapter 3 Copyright©2004 by Houghton Mifflin Company. All rights reserved. 2 Universe Classified • Matter is the part of the universe that has mass and volume • Energy is the part of the universe that has the ability to do work • Chemistry is the study of matter –The properties of different types of matter –The way matter behaves when influenced by other matter and/or energy Copyright©2004 by Houghton Mifflin Company. All rights reserved. 3 States of Matter Copyright©2004 by Houghton Mifflin Company. All rights reserved. 4 Properties • Characteristics of the substance under observation • Properties can be either directly observable or the manner something interacts with other substances in the universe Copyright©2004 by Houghton Mifflin Company. All rights reserved. 5 Properties of Matter • Physical Properties are the characteristics of matter that do not affect the composition of the substance – Characteristics that are directly observable • Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy • Characteristics that describe the behavior of matter Copyright©2004 by Houghton Mifflin Company. All rights reserved. 6 Classify Each of the following as Physical or Chemical Properties The boiling point of ethyl alcohol is 78°C. Diamond is very hard. Sugar ferments to form ethyl alcohol. Copyright©2004 by Houghton Mifflin Company. All rights reserved. 7 Classify Each of the following as Physical or Chemical Properties The boiling point of ethyl alcohol is 78°C. – Physical property – describes inherent characteristic of alcohol – boiling point Diamond is very hard. – Physical property – describes inherent characteristic of diamond – hardness Sugar ferments to form ethyl alcohol. – Chemical property – describes behavior of sugar – forming a new substance (ethyl alcohol) Copyright©2004 by Houghton Mifflin Company. All rights reserved. 8 Changes in Matter • Physical Changes are changes to matter that do not result in a change the fundamental components that make that substance – State Changes – boiling, melting, condensing • Chemical Changes involve a change in the fundamental components of the substance – Produce a new substance – Chemical reaction – Reactants Products Copyright©2004 by Houghton Mifflin Company. All rights reserved. 9 Physical Changes: The Three States of Water Copyright©2004 by Houghton Mifflin Company. All rights reserved. 10 Chemical Changes: Electrolysis - the Decomposition Of Water by Electric Current Copyright©2004 by Houghton Mifflin Company. All rights reserved. 11 Classify Each of the following as Physical or Chemical Changes Iron metal is melted. Iron combines with oxygen to form rust. Sugar ferments to form ethyl alcohol. Copyright©2004 by Houghton Mifflin Company. All rights reserved. 12 Classify Each of the following as Physical or Chemical Changes Iron is melted. – Physical change – describes a state change, but the material is still iron Iron combines with oxygen to form rust.. – Chemical change – describes how iron and oxygen react to make a new substance, rust Sugar ferments to form ethyl alcohol. – Chemical change – describes how sugar forms a new substance (ethyl alcohol) Copyright©2004 by Houghton Mifflin Company. All rights reserved. 13 Elements and Compounds • Substances which can not be broken down into simpler substances by chemical reactions are called elements • Most substances are chemical combinations of elements. These are called compounds. – Compounds are made of elements – Compounds can be broken down into elements – Properties of the compound are not related to the properties of the elements that compose it – Same chemical composition at all times Copyright©2004 by Houghton Mifflin Company. All rights reserved. 14 Classification of Matter Matter Pure Substance Constant Composition Homogeneous Mixture Variable Composition • Homogeneous = uniform throughout, appears to be one thing – pure substances – solutions (homogeneous mixtures) • Heterogeneous = non-uniform, contains regions with different properties than other regions Copyright©2004 by Houghton Mifflin Company. All rights reserved. 15 Pure Substances vs. Mixtures • Pure Substances – All samples have the same physical and chemical properties elements or compounds – Constant Composition all samples have the same composition – Homogeneous – Separate into components based on chemical properties • Mixtures – Different samples may show different properties – Variable composition – Homogeneous or Heterogeneous – Separate into components based on physical properties • All mixtures are made of pure substances Copyright©2004 by Houghton Mifflin Company. All rights reserved. 16 Identity Each of the following as a Pure Substance, Homogeneous Mixture or Heterogeneous Mixture Table salt in water Sand in water Copper metal Copyright©2004 by Houghton Mifflin Company. All rights reserved. 17 Identity Each of the following as a Pure Substance, Homogeneous Mixture or Heterogeneous Mixture Table salt in water – a homogenous mixture - solution Sand in water – a heterogeneous mixture Copper metal – A pure substance (all elements are pure substances) Copyright©2004 by Houghton Mifflin Company. All rights reserved. 18 Separation of Mixtures • Separate mixtures based on different physical properties of the components – Physical change Different Physical Property Technique Boiling Point Distillation State of Matter (solid/liquid/gas) Adherence to a Surface Filtration Chromatography Volatility Evaporation Copyright©2004 by Houghton Mifflin Company. All rights reserved. 19 Distillation Copyright©2004 by Houghton Mifflin Company. All rights reserved. 20 Energy and Energy Changes • Capacity to do work – chemical, mechanical, thermal, electrical, radiant, sound, nuclear • Energy may affect matter – e.g. raise its temperature (heat energy), eventually causing a state change – All physical changes and chemical changes involve energy changes Copyright©2004 by Houghton Mifflin Company. All rights reserved. 21 Heat Heat: a flow of energy due to a temperature difference Copyright©2004 by Houghton Mifflin Company. All rights reserved. 22 Heat • Heat: a flow of energy due to a temperature difference 1. Exothermic = A process that results in the evolution of heat. • Example: when a match is struck, it is an exothermic process because energy is produced as heat. 2. Endothermic = A process that absorbs energy. • Example: melting ice to form liquid water is an endothermic process. Copyright©2004 by Houghton Mifflin Company. All rights reserved. 23 Units of Energy • One calorie is the amount of energy needed to raise the temperature of one gram of water by 1°C – kcal = energy needed to raise the temperature of 1000 g of water 1°C • joule – 4.184 J = 1 cal • In nutrition, calories are capitalized – 1 Cal = 1 kcal Copyright©2004 by Houghton Mifflin Company. All rights reserved. 24 Example - Converting Calories to Joules Convert 60.1 cal to joules: 1 cal 4.184 joules 4.184 J 60.1cal 251J 1 cal Copyright©2004 by Houghton Mifflin Company. All rights reserved. 25 Energy and the Temperature of Matter • The amount the temperature of an object increases depends on the amount of heat added (Q). – If you double the added heat energy the temperature will increase twice as much. • The amount the temperature of an object increases depends on its mass – If you double the mass it will take twice as much heat energy to raise the temperature the same amount. Copyright©2004 by Houghton Mifflin Company. All rights reserved. 26 Specific Heat Capacity • Specific Heat (s) is the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree J By definition , the specific heat of water is 4.184 g C Amount of Heat = Specific Heat x Mass x Temperature Change Q = s x m x T Copyright©2004 by Houghton Mifflin Company. All rights reserved. 27 Example 1 – Calculate the amount of heat energy (in joules) needed to raise the temperature of 7.40 g of water from 29.0°C to 46.0°C: JJ Specific Heat of Water = 4.184 gg-CC Mass = 7.40 g Temperature Change = 46.0°C – 29.0°C = 17.0°C Q = s x m x T J Heat 4.184 7.40g 17.0C 526 J g C Copyright©2004 by Houghton Mifflin Company. All rights reserved. 28 Example 2 – A 1.6 g sample of metal that appears to be gold requires 5.8 J to raise the temperature from 23°C to 41°C. Is the metal pure gold (specific heat)? Q s m T Q s m T T 41C - 23C 18C 5.8 J J s 0.20 1.6 g x 18C g C Table 3.2 lists the specific heat of gold as 0.13 Therefore the metal cannot be pure gold. Copyright©2004 by Houghton Mifflin Company. All rights reserved. J g C 29