Rates of Reaction Mrs. Coyle How fast does

Rates of Reaction Mrs. Coyle How fast does

Rates of Reaction Mrs. Coyle How fast does aging occur? http://www.ging-strategie.de/Anti%20Aging%20Strategie.JPG How fast does the candle burn?

http://images.usatoday.com/tech/_photos/2006/03/28/aprilfig1.jpg Reaction Rate The speed with which products form from the reactants. Exo- and Endothermic Reactions

Exothermic reaction: reaction gives off energy. reactants products + energy Endothermic reaction: reaction takes in energy. energy

+ reactants products Bonds and Energy When bonds are broken: energy is absorbed.

(analogy: stretching a rubber band) When bonds are formed : energy is released. (analogy: releasing a stretched rubber band) Average bond energies, kcal/mole C-H 98

O-H 110 C-C 80

C-O 78 H-H 103

C-N 65 O=O 116 (2 x 58)

C=O 187* (2 x 93.5) C=C 145 (2 x 72.5)

(* as found in CO2) Ex: Exothermic H2 + Cl2 2 HCl + 183 kJ/mol Ex: Endothermic 2HgO + 181.7 kJ 2Hg + O2

Net Energy Change H= Potential Energy of Products -Potential Energy of Reactants H <0 exothermic H >0 endothermic Collision Theory of Reactions

http://staff.um.edu.mt/jgri1/teaching/che2372/notes/10/10_19.gif Activation Energy Minimum amount of kinetic energy the reactants must have in order to react.

The particles form an activated complex (transition state) that is an unstable arrangement of atoms that lasts a few moments. Then the products are formed.

Analogy http://www.800mainstreet.com/7/0007-004-reac_rate2.htm Potential Energy vs Time (Exothermic)

Heat of Reaction H Time http://staff.um.edu.mt/jgri1/teaching/che2372/notes/10/theory.html Energy vs Time (Endothermic)

Activation Energy Heat of Reaction H Reaction Rates are affected by: Concentration

Temperature Catalyst Surface Area (Particle Size) Mixing (Stirring) Concentration Effect on Reaction Rates The more concentrated, the higher the reaction rate.

Why? http://content.answers.com/main/content/wp/en/thumb/f/ff/525px-Molecular-collisions.jpg Temperature Effect on Reaction Rates The higher the temperature, the faster the rate.

Why? Catalyst Effect on Reaction Rates A catalyst lowers the activation energy, thus the reaction proceeds faster. Particle Size (Surface Area) The smaller the particle size the faster the

rate. Inhibitors Substances that negate the effect of the catalyst.

Recently Viewed Presentations

  • Value Engineering Workshop Mech 497 - McGill CIM

    Value Engineering Workshop Mech 497 - McGill CIM

    Times MS PGothic Arial Lucida Grande Wingdings New York Symbol Calibri Lightbar 1_Lightbar Adobe Acrobat Document Value Engineering Workshop MECH 497 Value Engineering Value Engineering Value Engineering Value Engineering Value Engineering Value Engineering Value Engineering Value Engineering Workshop Dates Organization...
  • Mine Warfare - Daum

    Mine Warfare - Daum

    Learning Objectives The student will know the mission of mine warfare. The student will know the methods of classifying mines. The student will know the basic types mines in the U.S. Navy's current inventory.
  • US-Russian Relations: Nuclear Arms Race and Disarmament

    US-Russian Relations: Nuclear Arms Race and Disarmament

    Arms Control, Disarmament, and International Security (ACDIS) at UIUC ... United States, on Japan, WWII Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945) Fat Man and Little Boy Estimated that between 115,000-170,000 were killed immediately Twice as many more...
  • What Kind of Engineer Am I? - AIChE

    What Kind of Engineer Am I? - AIChE

    What Kind of An Engineer Am I? A Friendly Competition I did the process design of the Space Shuttle Environmental Control System to make sure the astronauts have clean air onboard I design and supervise the manufacturing of the paper...
  • Nixon, Ford, Carter &amp; Reagan Presidencies

    Nixon, Ford, Carter & Reagan Presidencies

    Nixon's Foreign Policy . Gov't response to environmental & consumer movements . New Federalism. Reduce role of fed. gov't, increase state gov't . Revenue sharing - fed gov't gives some income to states. Slow inflation caused by Vietnam.
  • Chapter 4 Authentication Applications 1 Outline  Security Concerns

    Chapter 4 Authentication Applications 1 Outline Security Concerns

    A Kerberos realm consists of : A Kerberos server, with all user IDs and their passwords in its DB A number of clients, registered with the Kerberos server A number of application servers, sharing a key and registered with the...
  • Photo Album - جامعة الملك سعود

    Photo Album - جامعة الملك سعود

    Cont. Nature and Measurement of Sounds. Frequency of Sound Waves : When sound is generated, vibration ⇒ air molecules to move back and forth. this alternation ⇒ ↑ and ↓ in air pressure. Vibration forms sinusoidal (sine) waves. height of...
  • Hobbies - The World of Teaching

    Hobbies - The World of Teaching

    Which hobbies are the cheapest? How much money do you spend on your hobby? Does your hobby interfere with your study or personal life? Some men and women collect toys. Do you think they are too old for this? Do...