Matter and EnergyZumdahl Chapter 3

Grand Prismatic Spring in Yellowstone National Park

Source: David Maisel/Stone/Getty Images

Why does soda fizz when you open the bottle?

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

3.1 MatterAIMS

-learn about matter and its three states

What is matter??

Aristotle’s View….not science, but logic.

Matter What is Matter???

Anything that has mass and occupies a volume

“Matter is the real substance of which actual physical objects - the 'things' of this world - are composed.” Sir Roger Penrose.

Can also be thought of as being composed of protons, neutrons, and electrons (more on that later)

All Matter exists in one of 4 Physical States

Gaseous-no definite shape or volume

Liquid-definite volume, but not shape

Solid-definite shape and volume

Plasma-like gases, but atoms are made up of free electrons and ions of the element.

Figure 3.1: Liquid water takes the shape of its container.

Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior

gas liquid solid

assumes the shape and volume of its

container particles can move past one another

assumes the shape of the part of the container which it occupies

particles can move/slide past one another

retains a fixed volume and shape

rigid - particles locked into place

compressible lots of free space between particles

not easily compressible little free space between

particles

not easily compressible

little free space between particles

flows easily particles can move past one another

flows easily particles can move/slide

past one another

does not flow easily rigid - particles

cannot move/slide past one another

Examples of substances and their commonly found state Solid

Liquid

Gas

Ice cube, diamond, iron bar, rock

Gasoline, water, alcohol, blood

Air, helium, oxygen, natural gas

What determines the Physical State of a particular substance?

Temperature

Melting point or boiling point of substance

What causes a substance to change into another Physical State?

Addition of energy

-melting

-boiling Subtraction of Energy

-freezing

-condensing (condensation)

Densities of Physical States Gases

Least dense Occupy about

16oo greater volume than liquids

LiquidsDensity similar to solids, little less

SolidsMost dense of states

AeroGel—an ultra-low density solid

.Aerogels have a very good thermal resistance

This photo shows a 2.5 kgBrick being supported by only 2 grams of aerogel

Mercury, on the other hand, is a very dense liquid, denser than some solids

Figure 3.2: The three states of water.

3.2 Physical and Chemical Properties and ChangesAIMS

learn to distinguish between physical and chemical properties

-learn to distinguish between physical and chemical changes

Properties

Characteristics of the substance under observation

Properties can be either directly observable orthe manner something interacts with

other substances in the universe

Properties of Matter Physical Properties are the characteristics of

matter that can be observed 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

What is a Physical Property? A physical property is a characteristic of a substance

that does not change as you determine that property.Example: In order to determine that a domino is black, all you do is look at it. The domino remains unchanged during the testExample: In order to determine if a rock contains the mineral magnetite, you could place a paperclip nearby and see if it sticks. The rock remains unchanged during this test.

Examples of Physical Properties Odor Color Physical state Boiling/melting point Density Magnetic/not Hardness Radioactivity Malleability Ductility

Gallium metal has such a low melting point (30°C) that it melts from the heat of a hand.

An iron pyrite crystal (gold color) on a white quartz crystal.

Source: Chip Clark

What is a Chemical Property? A chemical property is a characteristic of a

substance which, when determining, will changean example would be …when determining the flammability of a substance, we must burn it, and thereby change it.chemical properties refer to the ability of a substance to form new substances

Some Chemical Properties Flammability

-is the material flammable? Reactivity

-does material react with another chemical, in what way?

pH What is the pH of the substance?

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)

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

What is a Physical change? Any change that does not change the

chemical makeup of a substance

Examples include: Changes in physical state Crushing, grinding, tearing

What is a Chemical change? Any change that results in materials with a

different chemical nature. Examples:

Electrolysis Burning (combustion) Silver tarnishing

Figure 3.3: Electrolysis, the decomposition of water by an

electric current, is a chemical process.

Electrolysis Link

Signs of a Chemical Change Color Change Formation of a gas (not from a phase change) Energy absorbed or given off

Gets cold or hot Gives off light/electric charge/other energy

Formation of a precipitate

Oxygen combines with the chemicals in wood to produce flames. Is a physical or chemical change taking place?

Source: Jim Pickerell/Stone/Getty Images

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.

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)

Classification of Matter

Homogeneous = uniform throughout, appears to be one thing pure substances solutions (homogeneous mixtures)

Heterogeneous = non-uniform, contains regions with different properties than other regions

P u re S ub s ta n ceC o n s tan t C o m p o s it ion

H o m o ge n e o us

M ix tu reV a ria b le C o m p o s it ion

M a tte r

3.3 Elements and CompoundsAIM: to understand the definitions of elements and compounds

Elements Cannot be separated into simpler substances Fundamental form of matter Examples include iron, oxygen, aluminum,

and hydrogen There are 90 naturally occurring elements,

about 118 known elements

Compounds Have same composition no matter where they

are found ALWAYS made up of atoms of 2 or more

elements, chemically combined Can be broken into the constituent elements

by chemical changes

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 not related to the

properties of the elements that compose it Same chemical composition at all times

A Model of an oxygen molecule….

Is this an element or a compound?

ElementElement

Compound

Would you put elemental sodium metal and chlorine gas on your popcorn?????

Or would you put a compound composed of sodium ion and chloride ion (NaCl) on it?

Mixtures vs. Pure Substances

Pure Substances vs. Mixtures Pure Substances

All samples have a unique set of physical and chemical properties Constant Composition all samples have the same composition Homogeneous (meaning same throughout) Separate into components based on chemical properties Include Elements and Compounds

Mixtures Different samples may show different properties Variable composition Homogeneous or Heterogeneous (different throughout) Separate into components based on physical properties

All mixtures are made of pure substances

Grain Probe, for sampling corn, soybeans, etc

Cream-top milk bottles

Types of Mixtures Solid mixtures can simply be a mix of various

substances, such as pancake mix, or a can of peas and carrots

Solid mixtures also include alloys which are physical mixtures of metals. examples 14 K gold, steel, brass

Examples Liquid mixture--Ocean water contains water,

dissolved salts, oxygen, and other gases Solid mixture--14 K gold contains gold and

other metals (only physically combined) Liquid mixture--Blood contains water,

dissolved ions, proteins, red blood cells

Element, Compound, or Mixture?

Types of Mixtures

Liquid mixtures fall into the following 3 categories... Solution—particles are dissolved and don’t settle out. Typically transparent, cannot be filtered

Salt water, Kool-Aid

Colloid-particle size a little bigger, still don’t settle out. Colloids exhibit Tyndall Effect, appear cloudy, murky, or opaque Milk, cloudy water, fog

Suspension—particles are fairly large, and will settle out of the mixture, separate upon standing still, can be filtered Air/dust, river water/gravel/mud/sand,

Behaviors of Mixtures Suspension - particles

are readily sedimented by gravity or by centrifugation.

True solutions and colloidal mixtures remain dispersed even following centrifugation.Soil suspension -

sedimentation bygravity

Suspension of blood cells -centrifugation at 500 x g

Hemoglobin (true solution)

Milk (colloidalmixture)

No change aftercentrifugation at10,000 x g

Separation of Mixtures Separate mixtures based on different

physical properties of the components Physical change

EvaporationVolatility

ChromatographyAdherence to a Surface

FiltrationState of Matter (solid/liquid/gas)

DistillationBoiling Point

TechniqueDifferent Physical Property

A honey extractor, separates honey from comb

Used coffee filterGraded sieves

Filter paper

Separatory Funnel

Figure 3.4: When table salt is stirred into water (left), a homogeneous mixture called a solution forms (right).

Figure 3.5: Sand and water do not mix to form a uniform mixture. After the mixture is stirred, the sand settles back to the bottom.

Figure 3.6: Distillation of a solution consisting of salt dissolved in water.

Identity Each of the following as a Pure Substance, Homogeneous Mixture or Heterogeneous Mixture

Gasoline a homogenous mixture

A stream with gravel on the bottom a heterogeneous mixture

Copper metal A pure substance (all elements are pure substances)

Figure 3.10: The organization of matter.

Organization of Matter

Quia - Mixtures, elements and compounds “Rags to Riches” Game

Energy and Energy Changes

Capacity to do work chemical, mechanical, thermal,

electrical, radiant, sound, nuclear Energy may affect matter

e.g. raise its temperature, eventually causing a state change

All physical changes and chemical changes involve energy changes

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.

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

Example - Converting Calories to Joules

Convert 60.1 cal to joules

Converting kcal to Joules

Convert 56.7 kcal to joules

Converting kJ to kcal

Convert 45.06 kJ to kcal

Figure 3.11: In ice, the water molecules vibrate randomly about their positions in the solid. Their motions are represented by arrows.

Figure 3.12: Equal masses of hot water and cold water separated by a thin metal wall in an insulated box.

Figure 3.13: The H2O molecules in hot water have much greater random motions than the H2O molecules in cold water.

Figure 3.14: The water samples now have the same temperature (50°C) and have the same random motions.

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.

A burning match releases energy.

Source: ElektraVision/PictureQuest

Specific Heat Capacity

Specific Heat (c) is the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree

C gJ

4.184 is water ofheat specific the,definitionBy

Amount of Heat = Mass x specific heat x Temperature ChangeQ = m x c x T

Example – 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

Mass = 7.40 g

Temperature Change = 46.0°C – 29.0°C = 17.0°C

J 526 C17.07.40gC g

J 4.184 Heat

Specific Heat of Water = 4.184 C-g

JC g

J

Q = m x c x T

Example – 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?

C gJ

0.20C18x g 1.6

J 5.8 s

C18 C23 - C41 TT m

Q s

Tms Q

Table 3.2 lists the specific heat of gold as 0.13Therefore the metal cannot be pure gold.

C g

J

Heating and Cooling Curves

Heating Curve As heat added to solid, it first raises the temperature of the solid to the

melting point Then added heat goes into melting the solid

Temperature stays at the melting point Heat of Fusion

As more heat added it raises the temperature of the liquid to the boiling point

Then added heat goes into boiling the liquid Temperature stays at the boiling point Heat of Vaporization

As more heat added it raises the temperature of the gas

Figure 13.2: The heating/cooling curve for water heated or cooled at a constant rate.

Heating/Cooling Curve web site http://

www.kentchemistry.com/links/Matter/HeatingCurve.htm

Energy Requirements forState Changes

In order to change a liquid to a gas, must supply the energy required to overcome the all the intermolecular attractions Not break bonds (intramolecular forces)

The energy required to boil 1 mole of a liquid is called the Heat of Vaporization Hvaporization = 40.6 kJ/mol for water at 100°C

Energy Requirements forState Changes

In order to change a solid to a liquid must supply the energy required to overcome the some of the intermolecular attractions

The energy required to melt 1 mole of a solid is called the Heat of Fusion Hfusion = 6.02 kJ/mol for ice at 0°C

Structures of the States of Matter In solids, the molecules have no translational

freedom, they are held in place by strong intermolecular attractive forces may only vibrate

In liquids, the molecules have some translational freedom, but not enough to escape their attraction for neighboring molecules they can slide past one another, rotate as well as vibrate

In gases, the molecules have “complete” freedom from each other

Why do Molecules Attract Each Other?

Intermolecular attractions are due to attractive forces between opposite charges

+ Ion to - ion + End of polar molecule to - end of polar molecule

H-bonding especially strong Larger the charge = Stronger attraction Even non-polar molecules have attractions due to

opposite charges London Dispersion Forces

Figure 13.4: Intramolecular (bonding) forces exist between the atoms in a molecule and hold the molecule together. Intermolecular forces exist between molecules.