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Rates

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A set of slides created to teach Rates to learners at Bishops Diocesan College in Cape Town.

A set of slides created to teach Rates to learners at Bishops Diocesan College in Cape Town.

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  1. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Rates of Reaction Keith Warne
  2. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net O O Bond Energies • Energy is ………………….to break bonds E breaking = 2 x E(H-H) +1x (O=O) = • Energy ………………………when new bonds formed E forming = 4 x (H-O)= • Total energy change ΔH = E…………….. (Reactant)+ Ef…………………(prod) (-) 2H2 + O2 O O O 2H2O + O Energy taken in Energy given out
  3. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Energy Changes During Reactions ΔHr = Eprod – EReact = Hbreaking–Hforming PotentialEnergy PotentialEnergy E prod E react E prod E react The heat energy or Enthalpy (H) changes in a reaction are related to the BREAKING and FORMING of chemical bonds. Energy is TAKEN IN when bonds break and RELEASED when bonds form. The MINIMUM ENERGY REQUIRED to start the reaction is called the ACTIVATION ENERGY. (Ea) ΔHr < 0 (-) EXOTHERMIC ΔHr > 0 (+) ENDOTHERMIC Ea = Hbreaking Hforming Ea = Hbreaking Hforming The overall energy change for the reaction can be found by using either of the two equations below: Energy given off Energy taken in Activated complex
  4. For FULL presentation click HERE >> www.warnescience.net Rate Graphs Time /(s) FAST SLOW STOPPED Time /(s) FAST SLOW STOPPED SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> ScienceCafe
  5. For FULL presentation click HERE >> www.warnescience.net Factors Affecting Rate • Surface area - solids only - greater area …….. effective collisions. 4x2a 4xa 4xa 4xa4xa a 2a Total perimeter 16a Total perimeter 8a Dividing a solid into smaller pieces ………..…. the surface area. (Perimeter) SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY
  6. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net • Higher temperature: increases the spread of energies. • More particles have enough energy to react. • REACTION RATE INCREASES! Energy Distribution of Particles Energy NumberofParticles Ea
  7. For FULL presentation click HERE >> www.warnescience.net Catalysts A catalyst is a substance, which can alter the ………. of a reaction without being permanently ………………………at the end of it. Catalyst - affects number of effective collisions. a) a small amount of catalyst can produce a ……………..amount of chemical change. b) catalysts remain unchanged chemically, but they can change physically c) catalysts are very …………….to particular reactions.
  8. For FULL presentation click HERE >> www.warnescience.net EXAM QUESTIONS Nov 2010 SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY
  9. For FULL presentation click HERE >> www.warnescience.net Hi… This is a SAMPLE presentation only. My FULL presentations, which contain a lot more slides and other resources, are freely available on my resource sharing website: www.warnescience.net (paste into your browser if link above does not work) Have a look and enjoy! Keith Warne WarneScience

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