1. 3/15/12 - Bellringer What kind of reactions can you think of? (Think outside the box!) Turn in 4 bellringers from this week when finished.

2. Objectives 1. Identify the reactants and products in a chemical reaction. 2. Determine how a chemical reaction satisfies the law of the conservation of matter. 3. Determine how chemists express chemical changes using equations

3. Chapter 23 – Chemical Reactions 23.1 – Chemical Changes

4. Chemical Reactions Chemical reaction – a change in which one or more substances are converted to new substances Reactants – the substances that react Products – the new substances produced

5. Different Reactions Chemical reactions – use the ELECTRONS to form new substances Nuclear reactions - use the NUCLEUS to form new substances What does a chemical reaction look like?

6. Chemistry Kitchen

7. REACTANTS PRODUCTS

8. Think about it… If you burned a piece of paper, you end up with a pile of ashes. Once burned, is there… –More mass? –Same mass? –Less mass? Why?

9. Conservation of Mass Conservation of Mass - a Law that states in a chemical reaction, matter is not created or destroyed –Antoine Lavoisier experimented with mercury (II) oxide and heat –He found mass of products (liquid mercury and oxygen gas) equaled mass of reactants

10. 3/19/12 - Bellringer Boiling or freezing water is NOT a chemical reaction. Why? Turn in 4 bellringers from last week if absent Thursday.

11. Chemical Equation Uses chemical formulas and symbols to describe a chemical reaction and the product(s) it produces –Chemical formula expresses the relationship between elements in the compound and molecules they make up

12. Coefficients Numbers which represent the number of units of each substance in a reaction –Knowing coefficients of chemical reactions allows chemists to use the correct amount of reactants to predict the amount of products (law of conservation applies)

13. Example

14. Subscripts and Symbols Numbers which represent the number of atoms in a molecule of a particular element Symbols used to show state of reactants –(s) solids –(aq) aqueous –(l) liquid –(g) gas

15. Volcano with a Twist Reactants? Products?

16. Equation: NaHCO 3 + CH 3 COOH => CH 3 COO - Na + + H 2 O + CO 2 States? Conservation?

17. Notes Supplement Chemical equations will look similar to… #AB(state) + # CD(state) → #AC(state) + #BD(state) Reactants (left) → Products (right) Arrow means “yields”

18. Practice SnO 2 (s) + 2 H 2 (g) → Sn(s) + 2 H 2 O(g) CH 4 (g) + 2 O 2 (g) → CO 2 (g) + 2 H 2 O(g)

19. In class assignment / homework: Section 1 Reinforcement Balancing Chemical Equations PART A AND B ONLY

20. Closure Question SnO 2 (s) + 2 H 2 (g) → Sn(s) + 2 H 2 O(g) What are the reactants? What are the products? How is matter conserved / equalled out? What changed? (Compounds and States)