Reaction Rates

Reaction Rates8th gr. ChemistryWarm-up1s and 2s turn and face the 3s and 4sDiscuss your picture in your group and pick the best picture to represent catalyst and the best picture to represent inhibitor. Catalyst- a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.

Inhibitor- a substance that slows down or prevents a particular chemical reaction or other process

Chemical reaction- a reaction happens when two or more molecules interact and something happens.A chemical change is when you start with one compound and turn it into another. Ex- A steel garbage can rusting is a chemical reaction. That rusting happens because the iron (Fe) in the metal combines with oxygen (O2) in the atmosphere. Non-example- When a refrigerator or air conditioner cools the air, there is no reaction. That change in temperature is a physical change.SafetyWhat safety precautions must we take to ensure safety?Goggles at all times!ApronsLong pants and sneakersKeep glassware away from the edge of counter or sinkHandle hot glassware with care, use beaker tongsDo not eat or drink in the labPAY ATTENTION!Part A

Independent variable- is the factor that the investigator changes.What is the independent variable in Part A?A: Water temperature

Independent VariableReaction rate (s)Cold waterHot waterDependent variable- is the factor that changes because of the independent variable. The data that is collected.What is the dependent variable in Part A?A: Time in seconds that it takes for the tablet to dissolvePart BIndependent variable- is the factor that the investigator changes.What is the independent variable in Part B? A: Surface area of tablet

Independent variableReaction time (s) tabletCrushed tabletPart BDependent variable- is the factor that changes because of the independent variable. The data that is collected.What is the dependent variable in Part B?A: Time in seconds that it takes for the tablet to dissolve

Temperature and reactions ratesUsually, an increase in temperature is accompanied by an increase in the reaction rate. Temperature is a measure of the kinetic energy of a system, so higher temperature implies higher average kinetic energy of molecules and more collisions per unit time.Surface area and reaction ratesThe smaller the size of the solid particles, the greater the area that the reaction can take place in.So finely divided powder reacts more quickly than the same stuff in a great big lump!

Warm-up1s and 2s turn and face the 3s and 4sDiscuss your picture in your group and pick the best picture to represent exothermic and the best picture to represent endothermic.

Pd 3 and Pd 4- Hand in Criss-Cross paper!Exothermic- reaction or process accompanied by the release of heat.

Endothermic- a chemical reaction that requires heat in order to proceed

SafetyWhat safety precautions must we take to ensure safety?Goggles at all times!ApronsLong pants and sneakersKeep glassware away from the edge of counter or sinkWASH HANDS!Do not eat or drink in the labPAY ATTENTION!

Part AIf I add a piece of liver to hydrogen peroxide, then there will be a __________________ reaction.Part BIf I add baking soda to vinegar, then there will be a __________________ reaction. Remember to take the temperature BEFORE you put the liver in the H2O2 and BEFORE you add the baking soda (Na2CO3) to the vinegar!