Matter
description
Transcript of Matter
MatterChapter 3
2
What is Matter?• Anything that has mass and takes
up space.
2
Basic Building Blocks of Matter• Elements: Pure substances that
cannot be separated into simpler substances– Where can we find information about
elements?– Dmitri Mendeleev created the first
periodic table.
Classifications of Matter• Substances: matter that has uniform
and unchanging composition.
– Ex. Table salt, water, hydrogen, oxygen
Classifications of Matter• Mixture: combination of two or more
substances in which the substances retain their individual chemical properties– Heterogeneous: does NOT blend, can
distinguish parts– Homogeneous: does blend, CANNOT
distinguish parts• Called solutions
Compounds• Combination of two or more
elements.– Ex. Table salt (Sodium Chloride),
Water
Physical Properties of Matter
• A characteristic that can be observed without changing the composition– Ex. Density, color, odor, taste,
hardness, melting point, and boiling point, state of matter
Chemical Properties of Matter
• The ability of a substance to combine with or change into one or more other substances.– Ex. Flammability, change into a new
substance, rust
Physical vs Chemical Change
• Physical change: altering a substance appearance, but not its composition
• Chemical change: altering a substance’s composition– Be careful…this also changes its
appearance!!!
Indicators of Chemical Change
• Change of color (can also be physical change indicator)
• Change heat (exothermic/endothermic)
• Produces light• Produces gas (bubbles)• Forms precipitate (solid)• Change in smell
Liquids• Takes the shape of its container• Volume is constant• viscosity – how easily it’s poured• Fluidity – ability to flow• Compression – compressed very little, gases
have a greater ability to be compressed• Surface tension – overfilled glass of water• capillary action – meniscus, paper towels
Solids• Definite shape• Definite volume• Tightly packed particles• Crystalline – salt• Molecular – sugar – weak forces• Amorphous – glass, rubber
Gases• Do not have a definite shape• Do not have a definite volume• Can diffuse and effuse• Can be compressed and expanded• Have fluidity
States of MatterState of Matter
Definite Shape
Definite Volume
Particle Spacing
Particle Speed
Solid
Liquid
Gas
States of MatterState of Matter
Definite Shape
Definite Volume
Particle Spacing
Particle Speed
Solid YES YES VERY CLOSE
VERY SLOW
Liquid NO YES CLOSE SLOW
Gas NO NO FAR APART
FAST
Phase Changes
Gases
Solids Liquids
Condensation
Vaporization
Melting
Freezing
Sublim
ation
Depos
ition
Melting• Endothermic –heat is absorbed• Solid to a liquid • Melting point – temperature at which
the forces holding the molecules together are broken
• Example – Ice to water
Vaporization• Endothermic• Liquid to a gas• Evaporation is vaporization on the
surface• Boiling point – temperature at which
the vapor pressure of a liquid equals the external pressure
• Example: Water to steam
Sublimation• Endothermic• Solid goes directly to a gas, not
entering the liquid state• Example: Dry Ice
Condensation• Exothermic – releases heat• Opposite of vaporization – gas to
liquid• Dew in the morning• “sweat” on a glass
Deposition• Exothermic• Gas to a solid without going through
the liquid phase• Example: Snow
Freezing• Exothermic• Liquid to a solid• Freezing point – temperature when a
liquid is turned into a crystalline solid• Example: water to ice
Which is which?• Endo-all the “ hot” changes • Exo – all the “cold” changes
Phase Diagrams– Phase diagram – graph of pressure versus
temperature that shows the condition required for a specific substance to undergo a phase change
– Triple point – represents the temperature and pressure at which three phases of a substance can coexist
– Critical point- max pressure and temperature the substance can exist as a liquid
Phase Diagrams Con’t– Line that goes between liquid and solid
– whichever phase the line is leaning towards, that phase is less dense than the other
– Lines between all phases on a phase diagram indicate that both states of matter exist simultaneously (in equilibrium)
Phase Diagrams - Water
Solids
Liquids
Gas
Triple point
Temperature (°C)
Pre
ssur
e (a
tm)
217.75
373.99
1.00
100.00
Critical Point
Boiling point
Which is more dense? Solid water or liquid water?
Worksheet• Answer the questions about the
phase diagram.
Conservation of Mass• According to the Law of
Conservation of Mass states that matter can neither be created nor destroyed in a chemical change (reaction)
• Mass reactants = Mass products
Example Problem 3-1• In an experiment, 10.00 g of red
mercury (II) oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of oxygen formed in the reaction?
Analyze the Problem• What is/are the reactant(s)?
– Mercury (II) oxide
• What is/are the product(s)?– Oxygen and mercury
Solve for Unknown• Mass reactants = Mass products• Mass Mercury (II) oxide= Mass oxygen + Mass of Mercury
• 10.00g = x + 9.26g
• Mass of oxygen (x) = 10.00g -9.26g• Mass of oxygen = 0.74g
Percent by Mass• Is used to determine if compounds
made of the same elements are the same…
• Mass of element x 100 • Mass of compound
Example Problem• A 78.0g sample of an unknown
compound contains 12.4g of hydrogen. What is the percent by mass of hydrogen in the compound?–
% =mass of hydrogen x 100– mass of compound
– Answer: 15.9%