1 / 17

Chemical Reactions 1 or more substances changed into a new substance or substances

Chemical Reactions 1 or more substances changed into a new substance or substances. YIELD. Reactants: substances about to react Products: new substances produced Reactants Products. Law of Conservation of Mass.

quincy-collins
Download Presentation

Chemical Reactions 1 or more substances changed into a new substance or substances

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. Chemical Reactions1 or more substances changed into a new substance or substances

  2. YIELD Reactants: substances about to react Products: new substances produced Reactants Products

  3. Law of Conservation of Mass mass can neither be created nor destroyed in a chemical reaction

  4. Indicators of State • (s) or (cr): solid • (l): liquid • (aq): aqueous dissolved in water • (g): gas

  5. All Chemical Equations MUST BE BALANCEDNEVER change subscripts…Only change coefficients!

  6. Writing Balanced Chemical Equations • Describe the reaction in words • Rewrite using formulas and symbols • (Check for diatomic elements!) • 3. Check equation for atom balance • 4. Choose coefficients that balance the equation

  7. Types of Chemical Reactions

  8. Synthesis: 2 or more substances combine to form another more complex substance A+B  AB Decomposition: 1 substance breaks down into 2 or more simpler substances AB  A+B

  9. Single Displacement: 1 element replaces another in a compound A + BC  AC + B Cu + Ag(NO3)  Cu(NO3) + Ag

  10. Double Displacement: 2 ionic compounds in solution • Precipitate • Water • Gas AB + CD  AD + CB AgNO3(aq) + NaCl (aq)  AgCl (s) + NaNO3 (aq)

  11. Bond Energy • The amount of energy required to put a bond together is equal to the amount it takes to pull them apart. • Bonding to hydrogen atoms together absorbs 436 kj of energy. • When two hydrogen atoms are split how much energy is released? • 436 kj

  12. Endothermic Reaction: net absorption of energy • More energy is required to break bonds than to form new ones • Bonds formed have greater potential energy than bonds that were broken • Ex. Ice packs Exothermic Reaction: net release of energy • Less energy is required to break old bonds than to form new ones • Bonds formed have less potential energy than the bonds that were broken • Ex. Hand warmers

  13. Bond Energy and Conservation of Energy • Energy released in an exothermic reaction is NOT CREATED BY THE REACTION! • It was stored as potential energy in the bonds of the reactants • In an endothermic reaction the products store energy as potential energy rather than releasing it as heat.

  14. Activation Energy • Energy that may be needed to start a reation • Used to break the bonds in the reactants

  15. Catalyst: • A catalyst can increase the rate of a chemical reaction • Decreases the activation energy • Decreases costs making rxn more economical • The human body uses enzymes to catalyze reactions

  16. Exploring ad Catalyst: Lab In A Nutshell • The reaction did not take place until the heated copper was added • The copper was not consumed by the reaction • Regains original color • 2Cu + O2  2CUO • CuO + C2H5OH  C2H4O + H2O + Cu

  17. Read Catalysts for Food Production p. 319- 321

More Related