Matter

Chapter 2

The Basics of Matter

• Matter – is anything that has mass and takes up space – it is the “stuff” of which the universe is composed– Extensive properties – depend on the amount of

matter in a sample• Mass, Volume• Energy, molarity (dilute or concentrated)

– Intensive properties – depends on the type of matter in a sample, not the amount of matter• Density, freezing pt., boiling pt., absorbency, elasticity

The States of Matter

State Definition Examples

Solid Rigid; has a fixed shape and volume

Ice cube, diamond, iron bar

Liquid Has a definite volume but takes the shape of its container

Gasoline, water, alcohol, blood

Gas Has no fixed volume or shape; takes the shape and volume of its container

Air, helium, oxygen

Physical Properties

• Things you can tell about a substance just by looking at it

• You don’t need to alter the composition of the substance to determine these

• Examples: – Color - density– Odor - melting point– Volume - boiling point

MIXTURES AND PURE SUBSTANCES

• Always have the same composition• Pure substances are either elements or

compounds• Examples:– Pure water (not lake/ocean water)– Copper – Zinc– rubbing alcohol

PURE SUBSTANCES

• A substance with variable composition• Made up of multiple pure substances• Examples:– Air– Wood– Coffee– Cookie dough

MIXTURES

• Homogeneous mixture – looks the same throughout – can’t see different parts– Ex: Kool-Aid, sugar cookie dough

• Heterogeneous mixture – can see the different parts– Ex: chocolate chip cookie dough, sand and water

solution

Two Types of Mixtures

State whether each of the following is a pure substance, a homogeneous mixture, or a heterogeneous mixture.

- Maple syrup- The oxygen and helium in a scuba tank- Oil and vinegar salad dressing- Common salt (sodium chloride – NaCl)

Practice

State whether each of the following is a pure substance, a homogeneous mixture, or a heterogeneous mixture.

- Maple syrup HOMOGENEOUS MIXTURE- The oxygen and helium in a scuba tank

HOMOGENEOUS MIXTURE- Oil and vinegar salad dressing HETEROGENEOUS MIXTURE- Common salt (sodium chloride – NaCl) PURE SUBSTANCE

Practice

SEPARATION OF MIXTURES

• Boil the liquid off of a solution and leaves the other components behind

Laboratory display of distillation: 1: A heating device 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed control 13: Stirrer/heat plate 14: Heating (Oil/sand) bath 15: Stirring means e.g.(shown), anti-bumping granules or mechanical stirrer 16: Cooling bath.

Distillation

• Separates a liquid from the solid

• The liquid passes through the filter paper, but the solid particles are trapped

Filtration

Summary – Breaking Down Matter

MATTER

HETEROGENEOUS MIXTURES

HOMOGENEOUS MIXTURES

PURE SUBSTANCES

COMPOUNDSELEMENTS

Physical methods

Chemical methods

ELEMENTS AND COMPOUNDS

• Fundamental substances that cannot be broken down into other substances by chemical means

• Found on the Periodic Table of Elements (if it’s not on the chart, it’s not an element)

• Examples:– Aluminum– Oxygen– Hydrogen

ELEMENTS

• Compounds are combinations of different elements.

• They can be broken down into their constituent elements by chemical changes.

• A compound always has the same composition (i.e., the same combination of elements).

• Examples:– Water (H2O)

– Carbon Dioxide (CO2)

COMPOUNDS

• Hydrogen peroxide (H2O2)

• Mercury (Hg)

• Vanadium (V)

• Sodium chloride (NaCl)

Element or Compound?

• Hydrogen peroxide (H2O2)– compound

• Mercury (Hg)– element

• Vanadium (V)– element

• Sodium chloride (NaCl)– compound

Element or Compound?

CHEMICAL AND PHYSICAL PROPERTIES

Physical Properties

• Things you can tell about a substance just by looking at it

• You don’t need to alter the composition of the substance to determine these

• Examples: – Color - density– Odor - melting point– Volume - boiling point

Chemical Properties

• These refer to the ability of a substance to form new substances (i.e., its reactivity)

• Examples:– propane burns in the air– Baking soda fizzes if mixed with vinegar– A marshmallow gets black when toasted too long

in a campfire– Hydrogen and oxygen react violently

Chemical or Physical?

• The boiling point of a certain alcohol is 78°C.• Diamond is very hard.• Sugar ferments to form alcohol.• Gallium metal melts in your hand.• Platinum does not react with oxygen at room

temperature.• Your paper is white.

Chemical or Physical?

• The boiling point of a certain alcohol is 78°C.• Diamond is very hard.• Sugar ferments to form alcohol.• Gallium metal melts in your hand.• Platinum does not react with oxygen at room

temperature.• Your paper is white.

Green is physical. White is chemical.

CHEMICAL AND PHYSICAL CHANGES

Physical Changes

• Physical changes do not affect the composition of the substance.

• Examples:– State changes (solid liquidgas)• Melting• Evaporating• Freezing• etc

– Breaking a substance into smaller pieces

Chemical Changes

• Chemical changes involve a change in the composition of the substance.

• Examples:– Burning something – Reacting two substances to make something new– Running an electric current through water to

decompose water into hydrogen and oxygen

Some practice…Chemical or Physical?

• Iron metal is melted.• Iron combines with oxygen to form rust.• A piece of wood is burned in a fireplace.• A rock is broken into small pieces.• A log of wood is chopped up with an axe into

smaller pieces of wood.• Water evaporates to become water vapor.

Some practice…Chemical or Physical?

• Iron metal is melted.• Iron combines with oxygen to form rust.• A piece of wood is burned in a fireplace.• A rock is broken into small pieces.• A log of wood is chopped up with an axe into

smaller pieces of wood.• Water evaporates to become water vapor.

Green is physical. White is chemical.

Recognizing a Chemical Change

• Formation of a precipitate– A solid that forms and settles out of a liquid mixture

• Change in color– Some reactions result in a change from one color to another

• Production of a gas– Bubbles must be a new substance – Results of physical change are not new substances (ex:

boiling)• Transfer of energy

– Burning something gives off energy in the form of heat and light

Law of Conservation of Mass

“During any chemical reaction, the mass of the products is always equal to the mass of the

reactants.”

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