To Do… Electronic homework (Lon-Capa)

HW6 Type 1 due Monday, April 21 by 7 pm; HW6 Type 2 due Wednesday, April 23 by 7 pm

Wednesday’s lab: Be prepared Read lab book PreLab Assignment Proper attire Watch videos

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Big Ideas – Discussed All matter is made up of atoms. Atoms are in constant motion

(kinetic molecular theory). Chemical reactions are re-

arrangements of atoms (substances change into other substances).

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Big Ideas – To Be Discussed

Chemical changes are accompanied by energy changes.

At the same conditions, some substances are liquids, some are solids, and others are gases.

Atoms have structure.

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Questions to Consider: Why are there molecules? Why are there phases of

matter? Why does water, for example,

have the properties that it does?

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Overall goal:

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Clicker QuestionWhich is lower in potential energy? Which is more stable?

H2/O2 or H2O

Lower PE More StableA) H2/O2 H2O

B) H2O H2/O2

C) H2/O2 H2/O2

D) H2O H2O6

Big Ideas – Energy A system is more stable with

lower potential energy. Achieving low potential

energy is a driving force. Thus, if energy is transferred into a system, the system will work to transfer this energy out.

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Clicker QuestionWhich is lower in potential energy and more stable?

Lower PE More StableA) Unburned match Unburned Match

B) Burned Match Unburned match C) Burned Match Burned MatchD) Unburned match Burned Match

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Clicker QuestionA banana is frozen by liquid nitrogen. Label each process as endothermic or exothermic. (The system is underlined.) Banana Liquid Nitrogen

A) Endothermic EndothermicB) Exothermic EndothermicC) Endothermic ExothermicD) Exothermic Exothermic

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Clicker QuestionIs the freezing of water an endothermic or exothermic process? (The system is underlined.)

A) endothermicB) exothermicC) neither

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Exothermic: more energy leaves the system overall

Endothermic: more energy goes into the system overall

2H2 + O2 2H2O 2H2O 2H2 + O2 15