1. Today is Monday, February (!) 2 nd, 2015 Pre-Class: Identify the “chemistry” in this scene (and I don’t mean between the people). http://misslolasays.com/wp-content/uploads/2011/05/barbecue.png Hint: There are chemical changes and physical changes going on. Where are they? In This Lesson: Unit 1 Matter and Change (Lesson 1 of 6)

2. Today’s Agenda Matter Forms of matter Changes in matter Fire? http://civilianmilitaryintelligencegroup.com/wp-content/uploads/2010/08/en-greek-fire.jpg

3. By the end of this lesson… You should be able to distinguish between physical and chemical changes. You should be able to interpret a basic chemical reaction.

4. “What’s a matter?” First, where is this in my book? – P. 39 and following…

5. “What’s a matter?” What you might call “stuff,” scientists call matter. Matter is anything that has mass and volume (takes up space). – Things that are not matter: Love Religion Green – Things that are matter: Just about everything you could touch. Chemistry, then, is the study of matter and change.

6. Phases of Matter You probably learned about the phases of matter long before you even remember: – Solid – Liquid – Gas That’s all of ‘em, right? – There’s also plasma and Bose-Einstein Condensates. – We’ll talk about ‘em…

7. Phases of Matter So that we’re all on the same page… – Solid: – Liquid: – Gas: – Plasma:

8. Transitions As you know, matter is not always stuck in one phase. Take water, for example. As a… – …solid, we call it ice. – …liquid, we call it water. – …gas, we call it water vapor. And what determines which state it’s in? – Temperature (and pressure, too) Plus, there really distinct points at which these changes occur.

9. Matter and Change There are two types of changes that can occur in matter, physical and chemical. – Physical changes occur when only the form of a substance has changed. In other words, the substances are not changed into different substances. – Chemical changes occur when a substance changes into another substance (the composition changes). Most chemical changes come along with some distinct signs (two slides). Physical changes can be undone. Chemical changes tend to be irreversible.

10. Physical Changes in Matter Going from a solid to a liquid is called: – Melting (or fusion) Going from a liquid to a gas is called: – Evaporating (or vaporization) Going from a gas to a liquid is called: – Condensing Going from a liquid to a solid is called: – Freezing (or solidification) Going from a solid to a gas is called: – Sublimation Going from a gas to a solid is called: – Deposition

11. Chemical Changes You are probably witnessing a chemical change if you detect: – Color changes – Odor changes – Energy changes (as in heat) Important: Dissolving processes sometimes give off or absorb heat. Dissolving is a physical change. – Production of gases or solids

12. Examples of Physical and Chemical Changes Leaves changing color – Chemical change Cooking a burger – Chemical change Melting an ice cube – Physical change Rotting meat – Chemical change Rain forming and falling – Physical change Dissolving salt into water – Physical change

13. More Examples of Changes Let’s further investigate physical and chemical changes with a lab! – Chemical and Physical Changes Activity

14. Writing Chemical Reactions All chemical reactions have reactants and products. – The starting “ingredient(s)” are the reactants while the product(s) are the end result(s). They are typically written like this: Reactant + Reactant  Product + Product OR Reactant + Reactant  Product + Product IMPORTANT NOTE: The arrow means “yields.”

15. Writing Chemical Reactions Examples: H 2 + O 2  H 2 O – Reactants: Hydrogen (H 2 ), Oxygen (O 2 ) – Products: Water (H 2 O) 2Fe + 3H 2 O  Fe 2 O 3 + 3H 2 – Reactants: Iron (Fe), Water (H 2 O) – Products: Rust (Fe 2 O 3 ), Hydrogen (H 2 )

16. Writing Chemical Reactions Which is the reactant? Which is the product? – 2H 2 O  2H 2 + O 2 Reactants: – 2H 2 O Products: – 2H 2 –O2–O2

17. More on Chemical Reactions Scientists sometimes use symbols to describe what form the reactants or products are in: (s) means the item is a solid (l) means the item is a liquid (g) means the item is a gas (aq) means the item is aqueous (it’s dissolved but isn’t a liquid)

18. Conservation of Mass/Matter In any chemical reaction, mass is conserved. – In other words, the mass of the reactant(s) is the same as the mass of the product(s). – The elements on one side of the equation are the same as those on the other. – Matter cannot be created nor destroyed. This is called the Law of Conservation of Mass. Sometimes it is called the Law of Conservation of Matter. – Because if you’re conserving matter, you’re also conserving mass.

19. Aside: Chemistry History Among other things, Antoine- Laurent de Lavoisier discovered something concerning the Law of Conservation of Mass. – He noticed that rusting iron gained mass. What was the mass coming from? So what came of Lavoisier? – He was beheaded during the French Revolution. Sacre bleu! http://upload.wikimedia.org/wikipedia/commons/6/6c/Antoine_lavoisier_color.jpg Antoine-Laurent de Lavoisier

20. Aside: How Much Does A Soul Weigh? Meet Dr. Duncan MacDougall. In 1907, Dr. Mac decides to see if he can measure the mass of a soul. Since matter can neither be created nor destroyed, Mac (or “Om,” as he was called), measured the masses of six patients as they died on the table: – Two tests were invalid. – Two showed a drop in mass, then an increase. – One showed a drop, then increase, then drop. The first test performed registered a drop of 0.75 ounces, or 21 grams, hence the common “legend.” – MacDougall did the same tests with dogs and found no such results. http://boingboing.net/images/_images_front_picture_library_UK_dir_13_fortean_times_6877_12.jpg

21. Conservation of Mass/Matter Another way to look at the Law of Conservation of Mass (or Matter) is the difference between mass and weight. Mass is the amount of matter in a substance. That doesn’t change. Weight is the effect of gravity on an object’s mass. Compare: – http://www.exploratorium.edu/ronh/weight/ http://www.exploratorium.edu/ronh/weight/

22. The Law of Conservation of Mass It’s time we had a little firsthand experience with the Law of Conservation of Mass. – Conservation of Mass Lab!