2. Catalyst – March 15, 2011 Give the formula AND name for the following covalent compound

3. Today’s Agenda  Catalyst  Intro to Chemical Reactions!  Practice Time!  Exit Question

4. Today’s Objectives  SWBAT interpret chemical equations.  SWBAT write skeleton (formula) equations from word equations.

5. Chemical reactions are everywhere! Let’s see what Bill Nye has to say about them!

6. Do you remember what a chemical change is???? Key Point #1: A chemical change is a process involving one or more substances changing into NEW SUBSTANCES; this is also called a chemical reaction.

7. Chemical Equations! Key Point #2: We use CHEMICAL EQUATIONS to show what happens in chemical reactions. C 3 H 8 + 5 O 2  3 CO 2 + 4 H 2 0

8. Chemical Equations  Chemical equations are similar to algebraic equations in that the total number of atoms of each element must be equal on each side A mathematical equation: x + 2x = 3x A chemical equation: C 3 H 8 + 5 O 2  3 CO 2 + 4 H 2 0

9. Parts of a Chemical Equation Key Point #3: A chemical equation identifies the starting chemicals as REACTANTS and the finishing chemicals as PRODUCTS. Reactants  Products Example (combustion of propane) C 3 H 8 + 5 O 2  3 CO 2 + 4 H 2 0

10. 3 Types of Chemical Equations There are 3 ways to write chemical equations: 1. Word Equations 2. Skeleton Equations 3. Balanced Equations

11. Phase Notations There are 4 phase notations used in equations: 1. Solid (s) 2. Liquid (l) 3. Gas (g) 4. In water/Aqueous (aq)

12. Parts of Chemical Equations Reactants  Products C 3 H 8 + 5 O 2  3 CO 2 + 4 H 2 0 When you see “yields” or “produces” or “forms,” use an arrow (  ) When you see “reacts with” or “and,” use a plus sign (+)

13. Word Equations Key Point #4: Word equations use WORDS to show chemical reactions. Solid iron and chlorine gas react to form solid iron(III) chloride  It’s like a short “chemical sentence” describing a chemical reaction!

14. Skeleton Equations Key Point #5: Skeleton equations use CHEMICAL FORMULAS rather than words to identify products and reactants.

15. Word  Skeleton Examples 1. Write the skeleton equation from the following word equation: Solid iron and chlorine gas react to form solid iron(III) chloride. Just replace all names with formulas! Don’t forget phase notations!

16. Write the skeleton equation… Solid iron and chlorine gas react to form solid iron(III) chloride.  Metals: Just write the element symbol  Diatomics: Molecules with 2 atoms of the same element  Start at 7, make a 7, don’t forget the “H!” Skeleton Equation: Fe (s) + Cl 2 (g)  FeCl 3 (s)

17. Skeleton Equations – Examples  Write skeleton equations for the following word equations: 1. Solid magnesium and chlorine gas react to form solid magnesium chloride 2. The reaction of hydrogen gas and bromine gas yields hydrogen bromide gas 3. Aqueous sodium hydroxide reacts with aqueous hydrogen chloride to produce solid sodium chloride and aqueous dihydrogen monoxide.

18. Skeleton Equations – Your Turn!  Write the skeleton equations for the following word equations: 1. Hydrogen gas reacts with iodine gas to yield gaseous hydrogen iodide. 2. Gaseous carbon monoxide reacts with oxygen gas to produce carbon dioxide gas. 3. Solid potassium chlorate (ClO 3 1- ) yields solid potassium chloride and oxygen gas.

19. Exit Question 1. What is written on the LEFT side of the arrow in a chemical equation? 2. Write the skeleton equation for the following. Use phase notations! Solid lithium reacts with oxygen gas to produce solid lithium oxide.