Chapter 3: Matter: Properties and Change

Properties of MatterPhysical Property: Can be observed or measured without changing the sample’s composition. Examples: density,

color, taste, hardness, boiling point.

Properties of MatterChemical Property:The ability of a substance to combine with or change into another substanceExamples

Does it burn in air?Does it react with water?Is it relatively inert? (Does it

react with nothing?)

p. 60 # 2 – physical or chemical property?

(a) Iron and oxygen form rust(b) Iron is more dense than aluminum(c) Magnesium burns brightly when ignited

(d) Oil and water do not mix

(e) Mercury melts at -39C

Chemical

Physical

Chemical

PhysicalPhysical

Physical Change: Does not change the substance (melting, boiling)

Chemical Change: A new substance forms

Indicators of a Chemical Reaction What are the signs that a chemical reaction has occurred?

1. A gas has been produced (bubbles) 2. A change in color 3. A change in temperature 4. A precipitate forms (new solid

forms) 5. Light is produced 6. New odor 7. Explosion

Crumpling paper Burning paper Decomposition of H2O2 Cutting wood Crushing a can Melting ice Rusting

Physical Chemcial Chemical Physical Physical Physical Chemical

States of MatterWhat are the four states of matter?SolidLiquidGasPlasma

States of Matter

Compressibility: Can you compress it?

no no yes

Solid Liquid Gas

Melting

Sublimation

Freezing

Evaporation

Condensation

Deposition

Law of Conservation of Mass

In any physical change or chemical reaction, mass is conserved.

Mass can be neither created or destroyed.

Conservation of Mass• Law of Conservation of Mass

–During any chemical reaction, the mass of the products is always equal to the mass of the reactants.

Reactants Products

Massreactants = Massproducts

Conservation of Mass• Practice–Mercury (II) oxide is heated and forms

200 g mercury metal and 16 g oxygen gas. How much reactant did you start with?

2 HgO 2Hg(s) + O2 ?? 200 g 16 g

–Mass of HgO = 200 g + 16 g = 216 g

Conservation of Mass• Practice–10 g mercury (II) oxide is heated. 9.26 g

mercury metal remains in flask. How much oxygen formed?

2 HgO 2Hg(s) + O2 10. 00g 9.26 g ??

10 g = 9.26 + Mass of O2

Mass of O2 = 10.00 g – 9.26 g = 0.74 g