Agenda -Warm-up -Dry-erase practice -Chem Rxns notes -Practice worksheet Warm-Up Think back to the popcorn lab…What law were you proving and how did the lab prove it? This back to the Alka-Seltzer Lab…how did you increase the rate of the reaction (the top popping off?)

Dry Erase Practice

Counting Atoms 3NaOH 4CO2 2Fe2O3 5NaCl

Practice Balancing Reactions Zn + HCl ---> ZnCl2 + H2 S8 + O2 ---> SO3 Sb + O2 ---> Sb4O6

H3PO4 ---> H4P2O7 + H2O Zn + HCl ---> ZnCl2 + H2 Al2(SO4)3 + Ca(OH)2 ---> Al(OH)3 + CaSO4 S8 + O2 ---> SO3 FeS2 + O2 ---> Fe2O3 + SO2

-Potential NRG diagram wksht WarmUp Determine the type of chemical reaction and predict the product: H2 + O2  H2 + Cl2  2HCl How many grams of HCl can be produced if 7.25 g of Cl2 is reacted H2? Agenda: -WarmUp -Review Hmwk -Endo vs Exo notes -Potential NRG diagram wksht --Exit Slip

Endothermic Vs. Exothermic Reaction Graphs

Collision Theory the more collisions in a system, the more likely combinations of molecules will happen. It is the correctly aligned collisions that allow for chemical reactions to occur

What is activation energy? http://ed.ted.com/lessons/activation-energy-kickstarting-chemical-reactions-vance-kite

Activation Energy The lowest amount of energy particles must have in order to react Particles must hit at precisely the right way, otherwise they will not react with one another

What is the activation energy for the forward reaction?

What is the activation energy for the reverse reaction?

More Questions… What is the enthalpy change (ΔH) of reaction for the forward reaction? What is the enthalpy change (ΔH) of reaction for the reverse reaction?

Endothermic Vs. Exothermic Reaction Graphs Endothermic Reaction: a reaction in which the products have more stored energy than the reactants. The reaction ABSORBS energy from the surrounding environment and the products use up this energy to create chemical bonds. The products are colder than the reactants.

Endothermic Vs. Exothermic Reaction Graphs Exothermic Reaction: a reaction in which the products have less stored energy than the reactants. The reaction RELEASES energy when bonds are broken. The products are hotter than the reactants.

Exothermic Reaction Graph Activation Energy-the energy needed to start a reaction Energy stored in the Reactants E N R G Y Energy released in the reaction Energy Stored in the Products TIME

Endothermic Reaction Graph Activation Energy-the energy needed to start a reaction Energy Stored in the Products Energy stored in the Reactants E N R G Y Energy absorbed in the reaction TIME

What factors affect the speed of a reaction? http://ed.ted.com/lessons/how-to-speed-up-chemical-reactions-and-get-a-date

What does rate of reaction mean? The speed of different chemical reactions varies hugely. Some reactions are very fast and others are very slow. The speed of a reaction is called the rate of the reaction. What is the rate of these reactions? rusting explosion baking

Chemical Reaction Rates Factors that affect the rate of chemical reactions Temperature Concentration Surface area Catalyst

Temperature Temperature—increase in temperature, chemical reaction rate increases. Increase in temperature means there is an increase in collisions and a faster reaction rate.

Concentration Concentration—the more concentrated a substance is, the faster a chemical reaction takes place. More concentrated means there are more particles per unit volume.

Surface Area Alka-Seltzer? Surface Area—greater the surface area, increase in reaction rate. Greater surface area—smaller particles

Catalyst Catalyst—speeds up a reaction without permanently changing itself. Lowers the amount of energy needed to start a reaction.

-Review worksheet from previous class Agenda: -Warm-Up -Review worksheet from previous class -Begin test review Warm-Up Explain what two things are needed for a chemical reaction to occur. Explain what a catalyst is. What is the activation energy of the forward reaction?