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Chemistry Class Update - November 20, 2013

Stay informed about the latest assignments, tests, and topics covered in your chemistry class on November 20, 2013. Learn about energy change, thermochemistry, and reaction rates.

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Chemistry Class Update - November 20, 2013

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  1. November 20, 2013 When the bell rings, voice at ZERO and all electronics away including headphones. TURN IN YOUR LAB including POST-QUESTIONS and any late Hw. TURN IN HW #13. Have your vocab out on your desk. DO NOW: Around the room there are 7 stations. You are required to get the information at these stations down. Keep your volume at a level 1. You have 15min from the bell.

  2. Tutoring • Thursday afterschool in 710 (2:30-3:30pm)

  3. STEM PROJECT • Reschedule today? • Afterschool or at home • Google drive

  4. Homework 11-20-13 • Vocab column #2** • HW assignment #14** **graded

  5. Notebook Check 11-22-13 • Stoichiometry Island Flow Chart • Anticipation Guide Solutions (just the guide, not the reading) • Pink Solutions Vocabulary (both parts) • Colligative Properties Foldable

  6. Week of 11-18-13 • November 18: Solubility Lab Solubility Quiz Finish Solubility HW: Assignment #12, Finish lab post-questions • November 19: Energy Change and ThermoChemistry HW: Assignment #13, vocab column #1 • November 20: Energy Change and ThermoChemistry HW: Assignment #14, Vocab column #2 test corrections due Friday 11-22-13 • November 21: Energy and Thermochemistry Thermochem quiz HW: Vocab column #3, study for solutions test • November 22: Solutions Test , Notebook Check HW: ClEvR Report due Tuesday 11-26-13

  7. Objectives • SWBAT • Explain the factors that affect the rate of a reaction (Temperature, concentration, particle size, and presence of a catalyst)

  8. Thermochemistry!

  9. Rate of Reaction Demo • Glow Sticks

  10. Exothermic Processes Processes in which energy is released as it proceeds, and surroundings become warmer Reactants  Products + energy

  11. Endothermic Processes Processes in which energy is absorbed as it proceeds, and surroundings become colder Reactants + energy  Products

  12. Reaction Rates: 2NO2(g)  2NO(g) + O2(g) 1. Can measure disappearance of reactants 2. Can measure appearance of products 3. Are proportional stoichiometrically

  13. The Reaction Mechanism • Thereaction mechanism is the series of steps by which a chemical reaction occurs. • A chemical equation does not tell us how reactants become products; it is a summary of the overall process. Reactants  Products The  sign has represents the reaction mechanism, but gives no indication of the steps in the mechanism

  14. The Rate-Determining Step In a multi-step reaction, the slowest step is the rate-determining step. It therefore determines the rate of reaction.

  15. Factors Affecting Rate • Temperature Increasing temperature always increases the rate of a reaction. • Surface Area Increasing surface area increases the rate of a reaction • Concentration Increasing concentration USUALLY increases the rate of a reaction • Presence of Catalysts

  16. Catalysis • Catalyst: A substance that speeds up a reaction by lowering activation energy • Enzyme: A large molecule (usually a protein) that catalyzes biological reactions. • Homogeneous catalyst: Present in the same phase as the reacting molecules. • Heterogeneous catalyst: Present in a different phase than the reacting molecules.

  17. Endothermic Reaction w/Catalyst

  18. Exothermic Reaction w/Catalyst

  19. Energy Heat (Enthalpy) Change, ΔH • Energy is the capacity to do work, and can take many forms • Potential energy is stored energy or the energy of position • Kinetic energy is the energy of motion • Thermal energy (heat) is an outward manifestation of movement at the atomic level Definition:The amount of heat energy released or absorbed during a process.

  20. Specific Heat Practice

  21. Units for Measuring Heat The Joule is the SI system unit for measuring heat: The calorie is the heat required to raise the temperature of 1 gram of water by 1 Celsius degree

  22. Exothermic Processes Processes in which energy is released as it proceeds, and surroundings become warmer Reactants  Products + energy

  23. Endothermic Processes Processes in which energy is absorbed as it proceeds, and surroundings become colder Reactants + energy  Products

  24. Water phase changes constant Temperature remains __________ during a phase change.

  25. Phase Change Diagram Processes occur by addition of energy   Processes occur by removal of energy

  26. Phase Diagram • Represents phases as a function of temperature and pressure. • Critical temperature: temperature above which the vapor can not be liquefied. • Critical pressure: pressure required to liquefy AT the critical temperature. • Critical point: critical temperature and pressure (for water, Tc = 374°C and 218 atm).

  27. Phase Change Practice

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