Properties of Matter

1. Properties of Matter Properties and Changes

2. Physical Properties • Substance – matter that has a uniform and unchanging composition (pure substance) • Example: salt – NaCl, water – H2O • Salt water – not pure, changes w/location! • Physical properties – characteristics that can be observed or measured without changing the composition (includes pure substances) • viscosity hardness density • conductivity melting point color • malleability boiling point odor

3. Types of Physical Properties(Activity) • Extensive properties – dependent on amount present • Mass • weight • length • volume • Intensive properties – independent of amount present; used to identify a substance • Density luster conductivity • Color malleability hardness • Odor ductility melting/freezing/boiling point

4. Using Physical Properties • Identification of a material – crucial in solving crimes • Choose a material for a specific purpose - shoelaces • Separation of the substance • magnetic properties crystallization • filtration chromatography • distillation

5. Recognizing Physical Changes • Some of the properties of a material change, but the substances in the material remain the same – some are reversible • heating butter • crumpling paper • slicing a tomato • wrinkly shirt/iron • hair braiding • peeling oranges

6. Chemical Properties • Chemical properties – the ability of a substance to combine with or change into another substance • Iron + O2 -> Rust (FeO2) • CO2 + H20 -> C6H12O6 + O2 • EVERY SUBSTANCE HAS A UNIQUE SET OF PHYSICAL AND CHEMICAL PROPERTIES

7. Observing Chemical Properties • Flammability – ability to burn in the presence of oxygen • fuels fabric • fire starters flame-resistance • Reactivity – how readily a substance combines chemically with other substances • Oxygen – high, rust • Nitrogen - low

8. Recognizing Chemical Changes • Evidence of chemical changes include: • change in color – leaves on trees, banana peel, copper, silver • Production of gas – vinegar and baking soda, cake baking • Formation of a precipitate – acid + milk (protein goes through chemical change), cottage cheese

9. States of Matter • Materials can be classified as solids, liquids, gases, or plasma based on whether their shapes and volumes are definite or variable (plasma only occurs naturally in the form as lightning bolts) • Shape and volume are clues to how the particles within a material are arranged

10. Plasma • Free electrons are released at a very high temperature • lightning • sun • neon signs • fire

11. Solids • Definite shape and volume • Atoms are packed close together and have an orderly arrangement of particles • Changing the container doesn’t change the shape or volume of a solid • Examples: pencil, cafeteria tray, book, quarter • Can you change the shape or volume of an object that is solid?

12. Liquids • Definite volume and take the shape of its container • Can be poured, will take on a new shape • Atoms are close together, but their arrangement is more random than those of a solid • Examples: juice, water, mercury, honey

13. Gases • Does not have a definite shape nor a definite volume • Takes the shape and volume of its container • Atoms are not arranged in a regular pattern and can have a big space between them • Vapor – refers to the gaseous form of a substance that is a solid or liquid at room temp. • COMPRESSIBLE • Examples: Air, helium, natural gas

14. How well did you listen?… • A vapor and a gas are the same thing. • A liquid conforms to its container. • Particles of a gas are spaced closer together than particles of a liquid. • A solid has a definite shape but changeable volume.

15. Chemical Equations • A useful description of a chemical reaction tells you the substances present before and after the reaction • Reactants undergo the change and the new substances that are formed are the products • Reactants -> Products

16. Conservation of Mass • The law of conservation of mass states that mass is neither created nor destroyed • Piece of charcoal burns, gets smaller until it is a tiny pile of ash; charcoal is being converted into gaseous products • Mass of the products equal the mass of the charcoal and the oxygen reacted

17. Conservation of Mass • In order to show that mass is conserved during a reaction, a chemical equation must be balanced using coefficients – numbers that appear before the formulas • Mass of reactants = Mass of products • 2 H2 + O2 -> 2 H2O 4 g + 32g -> 36 g

18. Practice! 1. If 50 grams of sodium reacts with chlorine to form 126 grams of salt. How many grams of chlorine reacted? 2. If 20 grams of aluminum reacts with 200 grams of bromide to form aluminum bromide, and no aluminum is left after the reaction, but 23 grams of bromine remained unreacted. How any grams of aluminum bromide were formed?

19. Practice! 3. If 178.8 g of water is separated into hydrogen and oxygen gas, and the hydrogen gas has a mass of 20.0 g. What is the mass of the oxygen gas produced? 4. From a laboratory process, a student collects 28.0 g of hydrogen and 224.0 g of oxygen. How much water was originally involved in the process?

20. Practice! 5. A student carefully placed 23.0 g of sodium in a reactor with an excess quantity of chlorine gas. When the reaction is complete, the student obtained 58 grams of salt. How many grams of sodium reacted? 6. A 10 gram sample of iron reacts with oxygen to form 18.2 grams of ferric oxide. How many grams of oxygen reacted?

21. Practice! 7. From a laboratory experiment designed to separate water into hydrogen and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. How much water was initially involved in the process? 8. A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When the reaction was complete, the student obtained 39.7 g of sodium chloride. How many grams of chlorine gas reacted?

22. Practice! 9. In a flask, 10.3 g of aluminum reacted with 100 g of liquid bromine to form aluminum bromide. After the reaction, no aluminum remained, and 8.5 grams of bromine remained unreacted. How many grams of compound were formed? 10. A 10.0 g sample of magnesium reacts with oxygen to form 16.6 g of magnesium oxide. How many grams of oxygen reacted?