Introductory Chemistry, 3rd Edition Nivaldo Tro

Introductory Chemistry, 3rd Edition Nivaldo Tro
Chapter 3 Matter and Energy Roy Kennedy Massachusetts Bay Community College Wellesley Hills, MA 2009, Prentice Hall

Are matter & energy related
Matter is any particle with mass and volume Energy is simply matter that is moving 0 Kelvin is defined as the temperature when matter does not moving So temperature is related to moving mass Therefore: temperature and mass are related to energy That’s why any chemistry or physics equation with energy must relate mass and temperature. Tro's "Introductory Chemistry", Chapter 3

Tro's "Introductory Chemistry", Chapter 3
Around you Everything you can see, touch, smell or taste in your room is made of matter. Tro's "Introductory Chemistry", Chapter 3

What Is Matter? Matter is anything with mass. Typically, we think of tiny little pieces of mass as atoms and molecules because those 117 elements behave Newtonian. There are over 200 smaller particles that behave Quantunian. Tro's "Introductory Chemistry", Chapter 3

Energy: it’s just Mass and Velocity
Electrical Kinetic energy associated with the flow of electrical charge. Heat or Thermal Energy Kinetic energy associated with molecular motion. Light or Radiant Energy Kinetic energy associated with energy transitions in an atom. Nuclear Potential energy in the nucleus of atoms. Chemical Potential energy in the attachment of atoms or because of their position.

Atoms and Molecules Atoms are the tiny particles that make up all matter. In most substances, the atoms are joined together in units called molecules. The atoms are joined in specific geometric arrangements. Tro's "Introductory Chemistry", Chapter 3

Any matter can exist in one of 3 States
Solid Liquid Gas Tro's "Introductory Chemistry", Chapter 3

Structure Determines Properties
The atoms or molecules have different structures in solids, liquids, and gases − leading to different properties.

Solids The particles in a solid are packed close together and are fixed in position. Although they may vibrate. The close packing of the particles results in solids being incompressible. The inability of the particles to move around results in solids retaining their shape and volume when placed in a new container and prevents the particles from flowing. Tro's "Introductory Chemistry", Chapter 3

Solids, Continued Some solids have their particles arranged in an orderly geometric pattern—we call these crystalline solids. Salt and diamonds. Other solids have particles that do not show a regular geometric pattern over a long range—we call these amorphous solids. Plastic and glass. Tro's "Introductory Chemistry", Chapter 3

Liquids The particles in a liquid are closely packed, but they have some ability to move around. The close packing results in liquids being incompressible. The ability of the particles to move allows liquids to take the shape of their container and to flow. However, they don’t have enough freedom to escape and expand to fill the container. Tro's "Introductory Chemistry", Chapter 3

Gases In the gas state, the particles have complete freedom from each other. The particles are constantly flying around, bumping into each other and the container. In the gas state, there is a lot of empty space between the particles. On average. Tro's "Introductory Chemistry", Chapter 3

Gases, Continued Because there is a lot of empty space, the particles can be squeezed closer together. Therefore, gases are compressible. Because the particles are not held in close contact and are moving freely, gases expand to fill and take the shape of their container, and will flow. Tro's "Introductory Chemistry", Chapter 3

Matter: is it pure or impure
Pure Substance Constant Composition Homogeneous Mixture Variable Composition Matter Heterogeneous Pure Substance = All samples are made of the same pieces in the same percentages. Salt Mixtures = Different samples may have the same pieces in different percentages. Salt water Tro's "Introductory Chemistry", Chapter 3

Mixtures Heterogeneous Homogeneous 1. Made of multiple substances, whose presence can be seen. 2. Portions of a sample have different composition and properties. 1. Made of multiple substances, but appears to be one substance. 2. All portions of a sample have the same composition and properties. Tro's "Introductory Chemistry", Chapter 3

Matter Summary

Matter has Properties Physical Properties are the characteristics of matter that can be changed without changing its composition. 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. Tro's "Introductory Chemistry", Chapter 3

H2O Physical verses H2O Chemical
Chapter One

Physical Properties Melting Point Boiling Point Electrical Conductivity Thermal Conductivity Magnetism Malleability Ductility Specific Heat Color Order Taste Solid Liquid Gas Tro's "Introductory Chemistry", Chapter 3

Some Physical Properties of Iron
Iron is a silvery solid at room temperature with a metallic taste and smooth texture. Iron melts at 1538 °C and boils at 4428 °C. Iron’s density is 7.87 g/cm3. Iron can be magnetized. Iron conducts electricity, but not as well as most other common metals. Iron’s ductility and thermal conductivity are about average for a metal. It requires 0.45 J of heat energy to raise the temperature of one gram of iron by 1°C. Tro's "Introductory Chemistry", Chapter 3

Chemical Properties Acidity Basicity Inertness Explosiveness Inflammable Flammable Oxidizing Reducing Tro's "Introductory Chemistry", Chapter 3

Some Chemical Properties of Iron
Iron is easily oxidized in moist air to form rust. When iron is added to hydrochloric acid, it produces a solution of ferric chloride and hydrogen gas. Iron is more reactive than silver, but less reactive than magnesium. Tro's "Introductory Chemistry", Chapter 3

Quiz: is it a Physical or Chemical Property
Salt is a white, granular solid = physical. Salt melts at 801 °C = physical. Salt is stable at room temperature, it does not decompose = chemical. 36 g of salt will dissolve in 100 g of water = physical. When a clear, colorless solution of silver nitrate is added to a salt solution, a white solid forms = chemical. Tro's "Introductory Chemistry", Chapter 3

Matter has Properties, Matter can also go through Changes
Changes that alter the state or appearance of the matter without altering the composition are called physical changes. Changes that alter the composition of the matter are called chemical changes. During the chemical change, the atoms that are present rearrange into new molecules, but all of the original atoms are still present. Tro's "Introductory Chemistry", Chapter 3

Is it a Physical or Chemical Change?
A physical change results in a different form of the same substance. The kinds of molecules don’t change. A chemical change results in one or more completely new substances. Also called chemical reactions. The new substances have different molecules than the original substances. You will observe different physical properties because the new substances have their own physical properties. Tro's "Introductory Chemistry", Chapter 3

Phase Changes Are Physical Changes
Boiling = liquid to gas. Melting = solid to liquid. Subliming = solid to gas. Freezing = liquid to solid. Condensing = gas to liquid. Deposition = gas to solid. State changes require heating or cooling the substance. Evaporation is not a simple phase change, it is a solution process. Tro's "Introductory Chemistry", Chapter 3

Quiz: is it a Physical or Chemical change
Evaporation of rubbing alcohol = physical. Sugar turning black when heated = chemical. An egg splitting open and spilling out = physical. Sugar fermenting into alcohol = chemical. Bubbles escaping from soda = physical. Bubbles that form when hydrogen peroxide is mixed with blood = chemical. Tro's "Introductory Chemistry", Chapter 3

Separation of Mixtures
Separate mixtures based on different physical properties of the components. Physical change. Centrifugation and decanting Density Evaporation Volatility Chromatography Adherence to a surface Filtration State of matter (solid/liquid/gas) Distillation Boiling point Technique Different Physical Property Tro's "Introductory Chemistry", Chapter 3

Distillation: different boiling points
Tro's "Introductory Chemistry", Chapter 3

Filtration: different solubility's

Summary Moving Matter has Energy. Motion is related to temperature. All energy formulas are relations between mass and temperature Matter has 3 states Matter has properties Matter can change States/Properties/Change are all related to temperature and how much you have Tro's "Introductory Chemistry", Chapter 3

Law of Conservation of Mass
Antoine Lavoisier “Matter is neither created nor destroyed in a chemical reaction.” The total amount of matter present before a chemical reaction is always the same as the total amount after. butane oxygen  carbon dioxide + water 58 grams grams  grams grams 266 grams = grams Tro's "Introductory Chemistry", Chapter 3

Law of Conservation of Energy
“Energy can neither be created nor destroyed.” The total amount of energy in the universe is constant. There is no process that can increase or decrease that amount. Note: neither Mass nor Energy are ever destroyed Tro's "Introductory Chemistry", Chapter 3

Energy The Fundamental Principle of the Universe is Energy From the Greeks to Newton to Quantum Mechanics Energy is known as the capacity to do work and is simply calculated by knowing the mass and velocity of a particle. The harder you swing an ax the faster you can fall a tree. Guess what happens when you walk into a wall .005 mph or 500 mph Tro's "Introductory Chemistry", Chapter 3

Energy: it’s just Mass and Velocity
Electrical Kinetic energy associated with the flow of electrical charge. Heat or Thermal Energy Kinetic energy associated with molecular motion. Light or Radiant Energy Kinetic energy associated with energy transitions in an atom. Nuclear Potential energy in the nucleus of atoms. Chemical Potential energy in the attachment of atoms or because of their position.

To get Energy (electrical, thermal, light, nuclear, chemical)
You take slow moving particles and make them move faster As slow moving water falls, gravity pulls it faster. The water falls on top of a turbine, which moves a coil in a magnet to generate electricity.

You take slow moving particles and make them move faster

You take slow moving particles and make them move faster Binding energy is simply the amount of energy (and mass) released, when free nucleons join to form a nucleus; a gluon is released or absorbed Einstein's mass-energy equivalence formula E = mc² can be used to compute the binding energy

Kinds of Energy Kinetic and Potential
Potential energy is energy that is stored; slow moving Water flows because gravity pulls it downstream. However, the dam won’t allow it to move, so it has to store that energy. Kinetic energy is energy of motion, or energy that is being transferred from one object to another; fast moving. When the water flows over the dam, some of its potential energy is converted to kinetic energy of motion. Tro's "Introductory Chemistry", Chapter 3

Matter Possesses Energy
When a piece of matter possesses energy, it can give some or all of it to another object. All chemical and physical changes result in the matter changing energy. Tro's "Introductory Chemistry", Chapter 3

There’s No Such Thing as a Free Ride
When atoms contact each other, frictions is produced. You will often notice friction as sound or heat. So instead of useful energy, “anti-energy” friction slows your car down. Tro's "Introductory Chemistry", Chapter 3

Units of Energy Calorie (cal) is the amount of energy needed to raise one gram of water by 1 °C. kcal = energy needed to raise 1000 g of water 1 °C. food calories = kcals. Energy Conversion Factors 1 calorie (cal) = 4.184 joules (J) 1 Calorie (Cal) 1000 calories (cal) 1 kilowatt-hour (kWh) 3.60 x 106 joules (J) Tro's "Introductory Chemistry", Chapter 3

Energy Use 2008 Unit Energy Required to Raise Temperature of 1 g of Water by 1°C Energy Required to Light 100-W Bulb for 1 Hour Energy Used by Average U.S. Citizen in 1 Day joule (J) 4.18 3.6 x 105 9.0 x 108 calorie (cal) 1.00 8.60 x 104 2.2 x 108 Calorie (Cal) 1.00 x 10-3 86.0 2.2 x 105 kWh 1.1 x 10-6 0.100 2.50 x 102 Tro's "Introductory Chemistry", Chapter 3

Ex 3.5, A candy bar has 225 Cal, convert to Joules
Write down the Given quantity and its unit. Given: 225 Cal 3 sig figs Write down the quantity you want to Find and unit. Find: ? J Write down the appropriate Conversion Factors. Conversion Factors: 1 Cal = 1000 cal 1 cal = J Write a Solution Map. Solution Map: Cal cal J Follow the solution map to Solve the problem. Solution: Significant figures and round. Round: 225 Cal = 9.41 x 105 J 3 significant figures Check. Check: Units and magnitude are correct.

Chemical Potential Energy
The amount of energy stored in a material is its chemical potential energy. The stored energy arises mainly from the attachments between atoms in the molecules the attractive forces between molecules. Tro's "Introductory Chemistry", Chapter 3

Exothermic Processes When a change results in the release of energy it is called an exothermic process. An exothermic chemical reaction occurs when the reactants have more chemical potential energy than the products. The excess energy is released into the surrounding materials, adding energy to them. Often the surrounding materials get hotter from the energy released by the reaction. Tro's "Introductory Chemistry", Chapter 3

An Exothermic Reaction
Surroundings reaction Potential energy Reactants Products Amount of energy released Tro's "Introductory Chemistry", Chapter 3

Endothermic Processes
When a change requires the absorption of energy it is called an endothermic process. An endothermic chemical reaction occurs when the products have more chemical potential energy than the reactants. The required energy is absorbed from the surrounding materials, taking energy from them. Often the surrounding materials get colder due to the energy being removed by the reaction. Tro's "Introductory Chemistry", Chapter 3

An Endothermic Reaction
Surroundings reaction Potential energy Products Reactants Amount of energy absorbed Tro's "Introductory Chemistry", Chapter 3

Temperature Scales Celsius Kelvin Fahrenheit Rankine 100°C 373 K 212°F
Boiling point water 298 K 75°F 534 R Room temp 25°C 0°C 273 K 32°F 459 R Melting point ice -38.9°C 234.1 K -38°F 421 R Boiling point mercury -183°C 90 K -297°F 162 R Boiling point oxygen BP helium -269°C 4 K -452°F 7 R -273°C 0 K -459 °F 0 R Absolute zero Celsius Kelvin Fahrenheit Rankine

Fahrenheit vs. Celsius A Celsius degree is 1.8 times larger than a Fahrenheit degree. The standard used for 0° on the Fahrenheit scale is a lower temperature than the standard used for 0° on the Celsius scale. Tro's "Introductory Chemistry", Chapter 3

The Kelvin Temperature Scale
Both the Celsius and Fahrenheit scales have negative numbers. Yet, real physical things are always positive amounts! The Kelvin scale is an absolute scale, meaning it measures the actual temperature of an object. 0 K is called absolute zero, all molecular motion stops. 0 K = -273 °C = -459 °F. Absolute zero is a theoretical value obtained by following patterns mathematically. Tro's "Introductory Chemistry", Chapter 3

Kelvin vs. Celsius The size of a “degree” on the Kelvin scale is the same as on the Celsius scale. Although technically, we don’t call the divisions on the Kelvin scale degrees; we call them kelvins! That makes 1 K 1.8 times larger than 1 °F. The 0 standard on the Kelvin scale is a much lower temperature than on the Celsius scale. When converting between kelvins and °C, remember that the kelvin temperature is always the larger number and always positive! Tro's "Introductory Chemistry", Chapter 3

Example 3.7—Convert –25 °C to Kelvins
Write down the Given quantity and its unit. Given: -25 °C units place Write down the quantity you want to Find and unit. Find: K Write down the appropriate Equations. Equation: K = ° C + 273 Write a Solution Map. Solution Map: ° C K Follow the solution map to Solve the problem. Solution: Significant figures and round. Round: 258 K units place Units and magnitude are correct. Check. Check:

Example 3.8—Convert 55° F to Celsius
Write down the Given quantity and its unit. Given: 55 °F units place and 2 sig figs Write down the quantity you want to Find and unit. Find: ° C Write down the appropriate Equations. Equation: Write a Solution Map. Solution Map: ° F ° C Follow the solution map to Solve the problem. Solution: Significant figures and round. Round: °C = 13 °C units place and 2 sig figs Check. Check: Units and magnitude are correct.

Example 3.9—Convert 310 K to Fahrenheit
Write down the Given quantity and its unit. Given: 310 K units place and 3 sig figs Write down the quantity you want to Find and unit. Find: °F Write down the appropriate Equations. Equation: K = °C + 273 Write a Solution Map. Solution Map: °F °C K °C = K - 273 Follow the solution map to Solve the problem. Solution: Significant figures and round. Round: 98.6 °F = 99 °F units place and 2 sig figs Check. Check: Units and magnitude are correct.

Practice—Convert 0 °F into Kelvin

Practice—Convert 0 °F into Kelvin, Continued
°C = 0.556(°F-32) °C = 0.556(0-32) °C = -18 °C K = °C + 273 K = (-18) + 273 K = 255 K Tro's "Introductory Chemistry", Chapter 3

Heat Capacity Heat capacity is the amount of heat a substance must absorb to raise its temperature by 1 °C. cal/°C or J/°C. Metals have low heat capacities; insulators have high heat capacities. Specific heat = heat capacity of 1 gram of the substance. cal/g°C or J/g°C. Water’s specific heat = J/g°C for liquid. Or cal/g°C. It is less for ice and steam.

Specific Heat Capacity
Specific heat is the amount of energy required to raise the temperature of one gram of a substance by 1 °C. The larger a material’s specific heat is, the more energy it takes to raise its temperature a given amount. Like density, specific heat is a property of the type of matter. It doesn’t matter how much material you have. It can be used to identify the type of matter. Water’s high specific heat is the reason it is such a good cooling agent. It absorbs a lot of heat for a relatively small mass. Tro's "Introductory Chemistry", Chapter 3

Specific Heat Capacities

Heat Gain or Loss by an Object
The amount of heat energy gained or lost by an object depends on 3 factors: how much material there is, what the material is, and how much the temperature changed. Amount of Heat = Mass x Heat Capacity x Temperature Change q = m x C x DT Tro's "Introductory Chemistry", Chapter 3

Units and magnitude are correct.
Example 3.10—Calculate Amount of Heat Needed to Raise Temperature of 2.5 g Ga from 25.0 to 29.9 °C Write down the Given quantity and its unit. Given: m = 2.5 g, T1 = 25.0 °C, T2= 29.9 °C, C = J/g°C Write down the quantity you want to Find and unit. Find: q, J Write down the appropriate Equations. Equation: Write a Solution Map. Solution Map: m, C, DT q Follow the solution map to Solve the problem. Solution: Significant figures and round. Round: 4.557 J = 4.6 J 2 significant figures Units and magnitude are correct. Check. Check:

Practice—Calculate the Amount of Heat Released When 7.40 g of Water Cools from 49° to 29 °C Tro's "Introductory Chemistry", Chapter 3

The unit and sign are correct.
Practice—Calculate the Amount of Heat Released When 7.40 g of Water Cools from 49° to 29 °C, Continued Sort Information Given: Find: T1 = 49 °C, T2 = 29 °C, m = 7.40 g q, J q = m ∙ Cs ∙ DT Cs = 4.18 J/gC (Table 3.4) Strategize Solution Map: Relationships: Cs m, DT q Follow the concept plan to solve the problem. Solution: Check. Check: The unit and sign are correct.

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