2. Do Now - April 20+8, 2009 1.You have 2 minutes to list the 4 types of chemical reactions. After you are finished, write your objectives and wait for further instructions.

3. Do Now - April 20+8, 2009 1.List the 4 types of chemical reactions. 2.List 2 characteristics of combustion reactions. 3.Using the following reaction, answer the following questions: 1) Is the equation balanced? 2) Will this reaction actually occur? 3 Ni + 2 AuBr 3  3 NiBr 2 + Au

4. Agenda Do Now/Announcements Double-Replacement Reactions What is energy? Energy Diagrams: Endo/Exothermic Foldable Work Time Exit Ticket

5. Objectives SWBAT relate the law of conservation of energy to chemical reactions. SWBAT distinguish between endothermic and exothermic reactions using descriptions, chemical equations, and graphs.

6. Single Replacement Example: Zn + CuCl 2  Zn Cl Cu + AB + C  AC + B Cl Zn Cu +

7. Such experiments reveal trends. The activity series ranks the relative reactivity of metals. It allows us to predict if certain chemicals will undergo single displacement reactions when mixed: metals near the top are most reactive and will displacing metals near the bottom. Q: Which of these will react? 1. Fe + CuSO 4  2. Ni + NaCl  3. Li + ZnCO 3  4. Al + CuCl 2  Cu + Fe 2 (SO 4 ) 3 Yes, Fe is above Cu NR (no reaction) No, Ni is below Na Zn + Li 2 CO 3 Cu + AlCl 3 Yes, Al is above Cu K Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au Yes, Li is above Zn

8. Reactivity of Halogens The same goes for halogens More active halogens will replace less active halogens List also on page 288 Q: Which of these will react? 5. F 2 (g) + 2 NaBr (aq)  6. I 2 (g) + 2 KCl (aq)  F Cl Br I Yes, F is above Br 2 NaF (aq) + Br 2 (l) NR (no reaction) No, I is below Cl

9. Single-Replacement Practice Problems Predict the products of the following reactions. Fe (s) + CuSO 4 (aq)  Br 2 (l) + MgCl 2 (aq)  Mg (s) + AlCl 3 (aq)  K Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au

11. 4. Double Replacement It’s like exchanging partners! A reaction which involves an exchange of ions between two compounds compound + compound  new compound + new compound AX + BY  AY + BX KNOW THIS!

12. 4. Double Replacement AX + BY  AY + BX A and B are cations (positively charged) X and Y are anions (negatively charged) You can see the anions have switched places and are now bonded to the other cations in the reaction

13. Examples of Double Replacement Reactions Ca(OH) 2 (aq) + 2 HCl(aq)  CaCl 2 (aq) + 2 H 2 O(l) Ions: Ca +2, OH -1, H +1, Cl -1 WATER IS FORMED! 2 NaOH(aq) + CuCl 2 (aq)  2 NaCl(aq) + Cu(OH) 2 (s) Ions: Na +1, OH -1, Cu +2, Cl -1 SOLID IS FORMED - PRECIPITATE KCN (aq) + HBr (aq)  KBr (aq) + HCN (g) Ions: K +1, CN -1, H +1, Br -1 GAS IS FORMED

14. Double Replacement Example: MgO + CaS AB + CD  AD + CB S O  Mg Ca + O S Mg Ca +

15. Double Replacement Practice Problems Page 291

16. Objectives SWBAT relate the law of conservation of energy to chemical reactions. SWBAT distinguish between exothermic and endothermic reactions using descriptions, chemical equations, and graphs.

17. Energy Energy is the ability to do work or produce heat UNITS: kilojoules (kJ) Two forms: 1) Potential 2) Kinetic (page 489)

18. Potential Energy Potential energy is due to composition or position of an object In chemistry, this has to do with types of atoms, number and types of bonds, and arrangements of atoms. (page 489)

19. Kinetic Energy Kinetic energy is the energy of motion In chemistry, this describes the motion of particles (page 490)

20. Law of Conservation of Energy The Law of Conservation of Energy states that in any chemical reaction, energy can be converted from one form to another, but it cannot be created or destroyed (page 490) Energy Reactants=Energy Products

21. Chemical Potential Energy Chemical potential energy is energy stored in a substance because of its composition (page 490) Example: C 8 H 18 <-- Octane (gasoline) –Gasoline burns (combusts) and produces heat

22. Energy in Chemical Reactions In every molecule, there is energy stored in the bonds –It takes energy to keep the atoms together Since the molecules change during a chemical reaction, the amount of energy keeping them together changes More energy might be needed or extra energy might be let go

23. Endothermic Reactions When MORE energy is needed to keep the new molecules together energy is absorbed from somewhere else The energy goes INSIDE the molecules Taking away energy to put it in molecules makes the reaction area feel COLD This is called an endothermic reaction –Endo- means inside THINK: Endo- and in

24. Endothermic Reactions Using the notes you just took, write a good definition for endothermic reaction

25. Exothermic Reactions When LESS energy is needed than before the extra energy is released The extra energy goes OUTSIDE the molecules The energy is used to make the molecules move faster, which makes the reaction area feel HOT This called an exothermic reaction –Exo- means outside THINK: Exo- and exit

26. Exothermic Reactions Using the notes you just took, write a good definition for exothermic reaction

27. Exit Ticket Write your own definitions for endothermic/exothermic reactions