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WARM - UP. Update your Table of Contents Write your homework – leave it to be stamped Get your homework out to be checked ! On your whiteboard, please draw a T-Chart compare and contrast endothermic & exothermic reactions with your table partner. Review….
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WARM - UP • Update your Table of Contents • Write your homework – leave it to be stamped • Get your homework out to be checked! • On your whiteboard, please draw a T-Chart compare and contrast endothermic & exothermic reactions with your table partner
Review… • The last few classes we focused on the idea of “What Goes In, Must Come Out,” BUT the Law of Conservation of Mass does not tell us anything about why a reaction occurs in the first place or the rate/speed at which they occur…
Endothermic or Exothermic? • 6CO2 + 6H2O + energy --> 6O2 + C6H12O6 • What is this the chemical equation for? • Photosynthesis • 6O2 + C6H12O6 --> 6H2O + 6CO2 + energy • What is this the chemical equation for? • Cellular Respiration
Rate of Reaction • The Rate of Reaction (speed) is dependent on the number of collisions between the molecules. What variables would increase/decrease the number of successful collisions? • With your group, brainstorm a list of things that you think affect the rate, or speed, of a chemical reaction and write them on your whiteboard!
What Affects the Rate of Reaction? • Many factors affect the rate of a chemical reaction, but you are responsible for knowing the 5 listed below: • Concentration • Temperature • Pressure • Surface Area • Catalysts
“Collision Theory” • What makes these reactions occur again? • Collisions between molecules – (molecules are bumping into each other and their valence electrons are bonding leading to a chemical reaction) • And how does this affect the Rate of Reaction? • More collisions = more reactions at a faster rate • Less collisions = less reactions at a slower rate
Rate of Reaction WebQuest • Use your technology to complete Parts 1-3 on your note guide • You may work with anyone so that you can share technology. • You have 20 minutes
Concentration Increasing the concentration (amount of a substance) increases the reaction rate…HERE’S WHY: • Packing more particles of a substance into the same amount of space • Causes particles to bump into each other more often (collision theory) • More contact = more reaction taking place So what does decreasing the concentration do?
Temperature Increasing the temperature, increases the reaction rate…HERE’S WHY: • Particles speed up, become hyper, move around more • Particles then bump into each other more (collision theory) • More contact = more reaction taking place So what does decreasing the temperature do?
Pressure Increasing thepressure, increases the reaction rate…HERE’S WHY: • Particles have less space to move in • Particles then bump into each other more (collision theory) • More contact = more reaction taking place So what does decreasing thepressuredo?
Catalysts Adding a catalyst increase the rate of reaction…HERE’S WHY: • Catalysts act as a “matchmaker” to jump start a reaction or make it faster • Without them reactions would be slower or not happen at all • Catalysts are not affected or used during the reaction – they are still left over Inhibitors are the opposite – how would you describe/define them?
Surface Area Increasing the surface area (by breaking something into multiple pieces) increases the reaction rate…HERE’S WHY: • More surface exposed means greater chance for particles to contact each other (collision theory) • More contact = more reaction taking place
Rate of Reaction Investigations • Group Leader – manages the group, reads the directions, makes sure everyone records data • Supply Manager – responsible for getting, returning and clean-up of supplies • Data Technician – takes any measurements necessary (temperature) and reports your group’s data to Ms. Sarnelli’s computer • Timekeeper – someone with a timer/stopwatch on their phone to time the reaction
Iodine Clock – • Send your supply manager to get 2 test tubes - some of you will receive solutions B1 &C and some of you will receive solutions B2 &C • Pour one of the solutions into the other and back again so all of the liquid is in one test tube…START YOUR TIMER IMMEDIATELY! • You must watch your experiment until you see the color change. If you are not paying attention, you will miss it! • Record the reaction times on your data table & decide as a group which factor affected the reaction rate!
Flubber • Send your supply manager to get your glue/water mixture, Borax and a popsicle stick. • Mix the Borax into the glue/water mixture and stir with the popsicle stick. • The borax DOES NOT BOND with the glue….it bonds the water with the glue, but is not part of the reaction….it is in the leftover liquid – • What role does the Borax play in this reaction?
Homework: • Review your Chemistry Vocabulary List so that you are prepared for the “Starburst Speedword” next class, AND the last test!
WARM - UP • Update your Table of Contents • Write your homework – leave it to be stamped • Get your Review Packet out to be checked!