1 / 26

Do Now - April 20+8, 2009

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

melba
Download Presentation

Do Now - April 20+8, 2009

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. Do Now - April 20+8, 2009 • List the 4 types of chemical reactions. • List 2 characteristics of combustion reactions. • Using the following reaction, answer the following questions: 1) Is the equation balanced? 2) Will this reaction actually occur? 3 Ni + 2 AuBr3 3 NiBr2 + Au

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

  4. 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.

  5. + +  Cl Cl Cl Cl Zn Zn Cu Cu Single Replacement Example: Zn + CuCl2 AB + C  AC + B

  6. No, Ni is below Na Yes, Li is above Zn Yes, Al is above Cu Yes, Fe is above Cu • 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 + CuSO4  2. Ni + NaCl  3. Li + ZnCO3  4. Al + CuCl2  Cu + Fe2(SO4)3 NR (no reaction) Zn + Li2CO3 Cu + AlCl3

  7. No, I is below Cl Yes, F is above Br 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. F2 (g) + 2 NaBr (aq)  6. I2 (g) + 2 KCl (aq)  2 NaF (aq) + Br2 (l) NR (no reaction)

  8. Single-ReplacementPractice Problems Predict the products of the following reactions. Fe (s) + CuSO4 (aq)  Br2 (l) + MgCl2 (aq)  Mg (s) + AlCl3 (aq) 

  9. 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!

  10. 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

  11. Examples of Double Replacement Reactions Ca(OH)2(aq) + 2 HCl(aq)  CaCl2(aq) + 2 H2O(l) Ions: Ca+2, OH-1, H+1, Cl-1 WATER IS FORMED! 2 NaOH(aq) + CuCl2(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

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

  13. Double Replacement Practice Problems • Page 291

  14. 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.

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

  16. Potential Energy Potential energyis 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)

  17. Kinetic Energy • Kinetic energy is the energy of motion • In chemistry, this describes the motion ofparticles (page 490)

  18. 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

  19. Chemical Potential Energy • Chemical potential energy is energy stored in a substance because of its composition (page 490) • Example: C8H18 <-- Octane (gasoline) • Gasoline burns (combusts) and produces heat

  20. 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

  21. EndothermicReactions • WhenMORE energy is needed to keep the new molecules togetherenergy 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

  22. EndothermicReactions Using the notes you just took, write a good definition for endothermic reaction

  23. Exothermic Reactions • WhenLESS energy is needed than beforethe 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

  24. ExothermicReactions Using the notes you just took, write a good definition for exothermic reaction

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

More Related