Properties of Matter Ch. 2

Quick Review  Matter is anything that: a) has mass, and b) takes up space  Mass = a measure of the amount of “stuff” (or material) the object contains (don’t confuse this with weight, a measure of gravity)  Volume = a measure of the space occupied by the object

States of Matter 1)Solid- matter that can not flow (definite shape) and has definite volume. 2)Liquid- definite volume but takes the shape of its container (flows). 3)Gas- a substance without definite volume or shape and can flow.  Vapor- a substance that is currently a gas, but normally is a liquid or solid at room temperature. (Which is correct: “water gas”, or “water vapor”?) 4) Plasma- Ionized gas that contains positive ions and electrons

Drawing the States of Matter Solid Liquid Gas

States of Matter Solid Liquid Gas Definite Volume ? YES NO Definite Shape? YES NO Result of a Temperature Increase? Small Expans ion Large Expansion Will it Compress? NO YES

The 6 Phase Changes 1.Melting: Solid to Liquid 2.Freezing: Liquid to Solid 3.Evaporation: Liquid to Gas 4.Condensation: Gas to Liquid 5.Sublimation: Solid to Gas 6.Deposition: Gas to Solid

Describing Matter Properties used to describe matter can be classified as: 1)Extensive – depends on the amount of matter in the sample - Mass, volume, calories are examples 2)Intensive – depends on the type of matter, not the amount present - Hardness, Boiling Point

Is Density Intensive or Extensive?

Properties  Words that describe matter (adjectives)  Physical Properties- a property that can be observed and measured without changing the material’s composition.  Examples- color, hardness, m.p., b.p.

Properties  Chemical Properties- a property that can only be observed by changing the composition of the material.  Examples- ability to burn, decompose, ferment, react with, etc.

Physical Change  Physical change will change the visible appearance, without changing the composition of the material.  Can be reversible, or irreversible  Boil, melt, cut, bend, split, crack  Is boiled water still water? ***ALL 6 PHASE CHANGES ARE PHYSICAL CHANGES!***

Chemical Change  Chemical Change - a change where a new form of matter is made.  Rust, burn, decompose, ferment

Signs of a Chemical Change 1.Gas production 2.Precipitate formation 3.Energy production (light, sound) 4.Change in Temperature 5.Change in color 6.Change in chemical or physical property

Chemical vs. Physical Change  Ask yourself: Is anything new being made?

3 Types of Matter 1.Elements 2.Compounds 3.Mixtures a. Heterogeneous b. Homogeneous (Solutions)

Pure Substances  Pure substances can be either  Elements  Compounds

1. Elements  Simplest kind of matter  Cannot be broken down any simpler and still have properties of that element!  All one kind of atom.  Atoms– the smallest particle or unit of an element that has the properties of that element.

2. Compounds  Substances that can be broken down only by chemical methods  When broken down, the pieces have completely different properties than the original compound.  Made of two or more atoms, chemically combined (not just a physical blend!)

3. Mixtures  Mixtures are a physical blend of at least two substances; have variable composition.  Every part keeps it’s own properties.  They can be either:

3. Mixtures (cont.) 1)Heterogeneous – the mixture is not uniform in composition Ex. Chocolate chip cookie, gravel, soil.

3. Mixtures (cont.) 2) Homogeneous - same composition throughout; called “solutions” Kool-aid, air, salt water

More on Homogenous (solutions)  Mixed molecule by molecule, thus too small to see the different parts  Can occur between any state of matter: gas in gas; liquid in gas; gas in liquid; solid in liquid; solid in solid (alloys), etc.  Most common solutions consist of 1 or more substances dissolved (the dissolved “stuff” is called the solute) in a liquid (called the solvent)  If the solvent is water—aqueous solution  A true solution will never separate or settle out on its own.

Ways of Separating Mixtures  Differences in physical properties can be used to separate mixtures. 1)Filtration - separates a solid from the liquid in a heterogeneous mixture (by size) 2)Distillation – separates a solution by boiling points There are other ways as well: magnets, evporation chromotography

Law of Conservation of Mass/Matter

 During any chemical reaction, the mass of the products (right side of arrow) is always equal to the mass of the reactants (left side of arrow).  All the mass can be accounted for:  Burning of wood results in products that appear to have less mass as ashes; where is the rest?

Example Problem When methane gas burns, and reacts and combines with oxygen to produce carbon dioxide and water vapor. If 4 grams of methane reacts with 16 grams of oxygen to produce 11 grams of carbon dioxide, how much water vapor is produced?