 Update your Table of Contents  Write your homework – leave it to be stamped  Be sure to turn your Civil War Project in. Paper projects in (or under) the basket. Flash drives on my desk. DateSession # ActivityPage # 1/25 14 Rate of Reactions Lab & Notes 21 Chemistry Vocabulary List 22

 Endothermic vs. Exothermic Reactions…what’s the difference?  With your group, draw a T-chart to compare and contrast them on your giant white board

 Needs energy to occur  Absorbs heat/energy  Temperature decreases; feels cold Examples:  Photosynthesis  Crackable ice packs

 Releases energy/heat  Temperature increases; feels warm/hot  Releases heat, sound or light energy Examples:  Cell Respiration  Glowsticks *Most reactions are exothermic

 The last few classes we focused on balancing chemical equations BUT balancing a chemical equation does not tell us anything about how fast or slow a reaction occurs  This is something called a Rate of Reaction

 With your group, brainstorm a list of things that you think affect the rate, or speed, of a chemical reaction and write it on your giant whiteboard

 Many factors affect the rate of a chemical reaction, but we are going to focus on 4: ◦ Surface Area ◦ Temperature ◦ Concentration ◦ Catalysts

 Use your technology to complete Parts 1-3 on your note guide  1 iPad per group  You may work with the group you are sitting with only  You have 30 minutes

Increasing the concentration (# of particles of a substance) increases the reaction rate…HERE’S WHY:  Packing more particles 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?

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?

Adding a catalyst increase the rate of reaction…HERE’S WHY:  Catalysts acts as a “helper” to jump start a reaction or move it along quicker  Without them reactions would be slow or not happen at all  Catalysts don’t get affected during reaction Enzymes are catalysts in our body…can you think of how an inhibitor would play a role in our body chemistry as well?

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

 Group Leader – manages the group, reads the directions, makes sure everyone records data  Data Technician – takes any measurements necessary (temperature) and reports your group’s data to Ms. Sarnelli  Timekeeper – someone with a timer/stopwatch on their phone to time the reaction  Supply Manager – responsible for getting, returning and clean-up of supplies

Independent Variable What is Affecting the Reaction Rate? TemperatureTime for Reaction to Complete Powdered Alka Seltzer Tablet THE SURFACE AERA N/A17 Seconds (More or less) Broken Alka Seltzer Tablet The surface areaN/A55.4 seconds Whole Alka Seltzer Tablet Surface areaN/A1:03.6 Room Temp Water Cold WaterTemperature2 degrees3:30 still going Hot WaterTemperature54 Degrees Celsius 25 seconds More IodineConcentrationN/A39.3 Less IodineConcentrationN/A2.48.9

Independent Variable What is Affecting the Reaction Rate? TemperatureTime for Reaction to Complete Powdered Alka Seltzer Tablet Surface areaN/A1:18 Broken Alka Seltzer Tablet Surface areaN/A1:51.8 Whole Alka Seltzer Tablet Surface areaN/A1:05 Room Temp Water Cold WaterTemperature5 Celsius2 minutes 8 Seconds Hot WaterTemperature62 Celsius26.3 Seconds More IodineConcentrationN/A11.7 Seconds Less IodineConcentrationN/A3 minutes 26 seconds

Independent Variable What is Affecting the Reaction Rate? TemperatureTime for Reaction to Complete Powdered Alka Seltzer Tablet N/A Broken Alka Seltzer Tablet N/A Whole Alka Seltzer Tablet N/A Room Temp Water Cold Water Hot Water More IodineN/A Less IodineN/A

 With your group write an overall summary of Rate of Reaction with your group to share with the class

 Are there any words or concepts that you want to add?  Are there words that you want to know the definition of? – Write it on the back of the sheet!  Review the list for next class so you are ready for Starburst SpeedWord