States of Matter
No definite shapeNo definite
volumeVery
compressible
No definite shapeDefinite volume
Not compressible
Definite shapeDefinite volume
Not compressible
What is a Vapor?• Vapor = gas• Use “vapor” for a gas that is a solid or liquid
at room temperature• Examples: water, bromine
Water is liquid at 20C Water is vapor at 100C
Substance: matter with uniform and definite composition
• Element
• The simplest form of matter that has a unique set of properties
• Cannot be broken down by chemical means
• 118 right now• Ex: carbon, oxygen,
hydrogen
• Compound
• A substance that contains two or more elements chemically combined in a fixed proportion
• Can be broken down by chemical means
• Glucose - C6H12O6
• Properties are very different from the elements it is made of
Mixture vs. Pure SubstanceMixture
• Composition can vary• Can be physically separated
Substance• Fixed composition• Water is always H2O• Can be chemically
separated
Mixture: physical blend of two or more components
• Heterogenous • NOT uniform composition• Ex: pepperoni pizza
• Homogenous• Uniform composition• Called “solution”• Can be solid, liquid, or gas• Ex: air
Heterogenous Mixtures and Phases
• Phase: any part of a sample with uniform composition and properties
There are 2 phases here!
Mixed sample has 1 phase!
Separating Mixtures
Filtration: separation by size difference
Chromatography: separation by
polarity difference
Properties of MatterChemical Property• How a substance reacts
to form other substances
• Ex: flammability, ability to react with acid
Physical Property• Can be observed or
measured without changing the composition of a substance
• Ex: color, density, melting point, boiling point, hardness
Two Types of Physical Properties
Extensive Property• Depends on amount of
material present• Mass and volume
Intensive Property• Depends on type of
matter, not amount• Color, hardness, density,
melting point, boiling point
Quick Check!Are these properties of Si physical or chemical?
• blue-gray color• physical• brittle• physical• does not dissolve in water• physical• reacts vigorously with water• chemical
Physical Change: substance changes appearance, NOT composition
Irreversible Change• Cannot be undone• Ex: cutting hair, ripping
paper
Reversible Change• Can be undone• Ex: change of state
Chemical Change
• Substance changes composition
• H2O(l) → H2(g) + O2(g)
• Ex: cooking, rotting, fermenting, rusting, exploding
• Chemical change =chemical reaction (rxn)
Clues for Chemical Changes
• Transfer of heat–Gets hot or cold, without YOU adding the heat
• Production of a gas– Bubbles appear, without YOU adding heat
• Formation of a precipitate– Solid forms from liquids– Cloudiness – means solid particles are in there
• Color change
Law of Conservation of Mass• “Matter is neither created nor
destroyed.”– Lavoisier, 1789
• Mass of products = mass of reactants– Need to mass precisely– Need to capture/measure gases
Merci, Monsieur Lavoisier!
Conservation of Mass Problems
• 27 g of water is broken down into oxygen gas and hydrogen gas. If 18 g of hydrogen is produced, how much oxygen is produced?–H2O H2 + O2
• Limonite (Fe2O3) is the mineral name for rust. If 28 g of limonite are produced from 15 g of Fe, how much O2 was used in the reaction?
– Fe + O2 Fe2O3