Matter and Change Get up, stand up! Stand up for your life!

What's the matter? You are putzing around the lab and come across an unlabeled beaker. You make observations and perform a few experiments (with the assistance of Ms. Goodrich, of course) and determine the unknown liquid has the following properties: (sit down when you know what it is!) Clear liquid Odorless Colorless Polar solvent Has high electronegativity Less dense in solid state than in liquid state Boiling point = 100°C Freezing point = 0°C Density = 1.0 g/mL

What's the matter? I found something in the woods and want to know what it is. Help me figure it out! (Sit down when you know what it is) Hard, easy to split, heat resistant Inexpensive and abundant Grows quickly and in great heights in tropical regions People use it to make flooring, fishing rods, and furniture Used to make chopsticks (no noticeable taste or odor) Favorite food of pandas

Describing matter Extensive properties – depends on amount of matter in a sample Ex: mass (amount of matter an object contains) Ex: volume (a measure of the space an object takes up) Intensive properties – depends on type of matter, not amount - density, boiling point, melting point, etc

Identifying Substances What’s a substance? Matter that has a uniform and definite composition Every sample of a given substance has identical intensive properties because every sample has the same composition Physical Property – a quality or condition of a substance that can be observed or measured WITHOUT CHANGING THE COMPOSITION! Examples: color, state of matter, melting point, boiling point, odor, etc.

Speaking of States of Matter... Solid – definite shape, definite volume, not easily compressed Liquid – indefinite shape, definite volume, not easily compressed Gas – indefinite shape, indefinite volume, easily compressed Vapor: gaseous state of a substance that is generally liquid or solid at room temperature

Don't go changin... Physical change: some properties of a material change, but the chemical composition of the material does not Can be classified as reversible and irreversible Boiling, freezing, splitting, melting, condensing, breaking, grinding, cutting, crushing, etc. Chemical change: a change that produces matter with a different composition than the original matter Burning, oxidizing, rusting, separating compounds

Mixtures Examples: trail mix, salads, salad dressing, sand, gravel, dirt, air So what is a mixture??? **a physical blend of 2 or more components**

Types of Mixtures Heterogeneous (cheesy baked potato soup) Composition is NOT uniform throughout You can usually see this fairly easily Homogeneous (swayt tay) Composition IS uniform throughout AKA: “solution” Many are liquids (coffee), some are gases (air), some are solids (steel, sterling silver, general jewelry) 24k gold = 100% gold, 18k gold = 75%

Separating Mixtures *Differences in physical properties can be used to separate mixtures* 1. Filtration – separates solids from liquids in a heterogeneous mixture 2. Distillation – separating water from particles dissolved in water a. liquid is boiled to produce vapor b. vapor is condensed into a liquid

Distillation Process

Elements vs. Compounds Element – simplest form of matter that has a unique set of properties Compound – substance that contains two or more elements chemically combined in a fixed proportion Example: carbon, hydrogen, oxygen (e or c?) Example: sugar (C6H12O6) **compounds can be broken down into simpler substances, elements cannot**

Breaking Down Compounds Basically – chemically changing the compound (chemical change, not physical) Sugar can be burned to form carbon and water vapor (from C6H12O6) Can carbon be broken down further??? Can water be broken down further??? Passing an electric current through water will form hydrogen gas and oxygen gas

Properties of Compounds Compound vs. its elements are VERY different Ex: sodium and chlorine vs. sodium chloride

Substances vs. Mixtures Milk Gasoline If the composition of a material is fixed, the material is a substance, if the composition varies, it’s a mixture Copy concept map on overhead

Chemical Reaction Remember: physical change - a quality or condition of a substance that can be observed or measured WITHOUT CHANGING THE COMPOSITION Chemical change – the composition of the matter always changes (also known as a chemical reaction)

Chemical Reaction How do you know one has happened? Color change Odor change Energy change Production of gases or solids (precipitates)

Chemical Reaction

Law of Conservation of Mass During ANY chemical reaction: mass of products always = mass of reactants In other words: in any physical change or chemical reaction, mass is always conserved (it is neither created nor destroyed)