What are some different possible types of energy? Some of your answers may have included…….

An important note about energy: The ______________________ says: Energy cannot be ____________ or ______________. Energy can, however, be ______________ from one substance to another.

To keep track of the ________________ that result from these transfers of energy, chemists use the terms _________ and ________________.

A _________ consists of all the components that are being studied at a given time. The _____________ include everything outside the system.

Energy in Chemical Reactions!!!

Every chemical reaction involves a change in __________ 1) Some reactions _______________ energy. Example: Gasoline + oxygen  carbon dioxide + ___________ This type of reaction will feel _____________. 2) Some reactions ______________ energy. Example: Baking soda + vinegar + ___________  carbon dioxide This type of reaction feels _________________.

Reactions are classified based on _______ in _______. 1)Exothermic Reactions: ____________ energy into their surroundings (energy exits the reaction) 2) Endothermic Reactions: ____________ energy from their surroundings (energy enters the reaction)

Getting Reactions Started ____________________ is the amount of energy that two _____________ must have before they can take part in a chemical reaction. The activation energy is represented with the letters E a

Graphing Reactions This graph shows how much energy the _________________ and ______________ have. ∆H = energy of the products – energy of the reactants Example using the above graph: 150 – 300 = -150 kJ When ∆H is +, then the reaction is endothermic When ∆H is -, then the reaction is exothermic Activated Complex

What does letter A represent? What does letter B represent? What does letter C represent? What does letter D represent? Calculate E a for this reaction: Calculate ∆H for this reaction: Does the graph represent an endothermic or exothermic reaction?

What does letter A represent? What does letter B represent? What does letter C represent? What does letter D represent? Calculate E a for this reaction: Calculate ∆H for this reaction: Does the graph represent an endothermic or exothermic reaction?