Why Does Matter Matter?

TEKS

• 4 (A) differentiate between physical and chemical changes and properties;

• 4 (B) identify extensive and intensive properties;

• 4 (D) classify matter as pure substances or mixtures through investigation of their properties.

Physical vs. Chemical Changes

• Examples:

– rusting iron

– dissolving in water

– burning a log

– melting ice

– grinding spices

• Chemical

• Physical

• Chemical

• Physical

• Physical

Sure Signs of a Sure Signs of a Chemical ChangeChemical Change

• Energy Change Energy Change (Temperature and (Temperature and Light)Light)

• Gas Produced (not Gas Produced (not from boiling!)from boiling!)

• Precipitate – a solid Precipitate – a solid formed by mixing formed by mixing two liquids togethertwo liquids together

• Color Change (Be Color Change (Be Careful)Careful)

http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA0/MOVIES/S1047.MOV

Physical ChangesPhysical Changes– can be observed without

changing the identity of the substance

Some Some physical changes physical changes would bewould be

• Phase ChangePhase Change– boiling of a liquidboiling of a liquid– melting of a solidmelting of a solid

• dissolving a solid in a dissolving a solid in a liquid to give a liquid to give a homogeneous mixture homogeneous mixture — — a SOLUTION.a SOLUTION.

Changes Quiz

Are the following changes considered chemical or physical?

• 1. Sharpening a pencil

• 2. Dissolving Koolaid in water

• 3. Silver Tarnishing

• 4. Alcohol evaporating

• 5. Milk souring

Chemical Properties and Chemical Properties and Chemical ChangeChemical Change

• Chemical change Chemical change or or chemical reactionchemical reaction — — transformation of one or transformation of one or more atoms or molecules more atoms or molecules into one or more different into one or more different molecules.molecules.

•Burning hydrogen (HBurning hydrogen (H22) in ) in oxygen (Ooxygen (O22) gives H) gives H22O.O.

Physical Physical Properties ( Properties ( see STAAR see STAAR field guide)field guide)What are some physical What are some physical

properties?properties?

• colorcolor

• melting and boiling melting and boiling pointpoint

• odorodor

GraphiteGraphite — — layer structure layer structure of carbon of carbon atoms reflects atoms reflects physical physical properties.properties.

Physical vs. Chemical Properties

• Examples:

– melting point

– flammable

– density

– magnetic

– tarnishes in air

physical

chemical

physical

physical

chemical

Physical Chemical Properties quiz

1. Combustible

2. Hard

3. 13 Kilograms

4. Boils at 200°C

5. Density of 6.1g/cm³

6. Corrodes in air

7. Soluble in water

8. Volatile in water

Chemical

Physical

Physical

Physical

Physical

Chemical

Physical

Chemical

What are Extensive and Intensive Properties?

All Physical Properties of Matter can be classified as Extensive or Intensive.

• Extensive Properties- depend on the amount of matter

Ex) Mass

• Intensive Properties- DOES NOT depend on the amount of matter.

Ex) luster, density (Mass/Volume ratio)

Determine Extensive or Intensive from the Physical properties on slide 9.

Intensive/Extensive Properties Quiz

• Hard

• 13 Kilograms

1. Boils at 200°C

2. Density of 6.1g/cm³

3. Corrodes in air

4. Soluble in water

Mixtures and Pure Substances• Matter can be classified as a mixture or a pure substance.

Mixtures

• A mixture has variable composition

• • A homogeneous mixture has the same properties throughout.

• A heterogeneous mixture has different properties in different parts of the mixture.

Separation of Mixtures distillation filtration

Separation of MixturesDecantation- is a process of carefully

pouring a solution from a container in order to leave the precipitate (sediments) in the bottom of the original container.

Chromatography- involves passing a mixture dissolved in a "mobile phase" through a stationary phase. Chromatography works on the principle that different compounds will have different solubilities and adsorption to the two phases, which will allow for their separation.

Pure Substances

A pure substance always has the same composition.

• Pure substances are of two types:

Elements which cannot be broken down chemically into simpler substances

Compounds which can be chemically broken down into elements

Water is a compound. All thecomponents are the same—H2O molecules.

Matter FlowchartMATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

Element

How can it be separated ? How can it be separated ?Filtration

Distillation

Chromatography

Chemically

Electrolysis

Nuclear Reaction

Types of Mixtures

• Variable combination of 2 or more pure substances.

Heterogeneous –visibly separate phases

Homogeneous – Same throughout