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Unformatted text preview: Chem 1A Course Outline: Bio/Life Theme Molecular Recognition:
Biological and chemical systems distinguish between molecules and regulate behavior accordingly. Lecture 22 Point of View: Heat Transfer Reaching Equilibrium:
Biological and chemical processes are dynamic and reversible, and the outcomes can be manipulated depending on conditions. Key Idea: Energy exchange is associated with chemical change. Engines of Life:
The energy currency (or coin) of living organisms is the making and breaking of bonds. Energy from the Sun:
Absorption of light causes the rearrangement of electrons, which in turn causes the growth of living organisms. Unit 3 syllabus on bspace Which state represents lower energy? Which state represents lower energy? Bullet at 500 m/s Bullet at 0 m/s Which state represents lower energy? Which state represents lower energy? Skier on top of a mountain Skier at the bottom of the mountain HOT COLD Which state represents lower energy? Which state represents lower energy? WATER ICE B A N G
H2 and O2 !!
H2O Which state represents lower energy? Predicting Change
Which state represents lower energy? A water glass standing on your desk vs. raised in the air Bullet at 0 m/s vs. bullet at 500 m/s A skier at the bottom of a mountain vs. on top of a mountain A toaster at room temperature vs. a toaster that is hot Ice in the freezer vs. liquid water in the freezer H2O molecules vs. H and O atoms Charred wood, vs. wood ready to be set on fire, plus O2 Respiration: C6H12O6 + 6 O2 ! 6 CO2 + 6 H2O Photosynthesis: 6 CO2 + 6 H2O ! C6H12O6 + 6 O2 Energy for atoms and molecules
Kinetic energy (motion) Potential Energy
For atoms and molecules
At short distances the potential energy is low (more negative). At larger distances the potential energy is less negative. translational translations Lattice energy = k
rotational rotations vibrations vibrational (Q1 )(Q2 ) r Potential energy (Coulomb attractions and repulsions) E dipole"dipole = ! k r3 bonds intermolecular E London = " Total energy is the sum of the kinetic and potential energy !
! k r6 Total Energy for a Closed System
H and O atoms H2 and O2 H2O Smallest KE Zero PE (by definition) Larger KE Negative PE Largest KE Most negative PE Total energy of an isolated system does not change (but most systems are in contact with the surroundings!) Energy is released to the surroundings when H2 and O2 rearrange to form H2O Energy is required from the surroundings to rearrange H2O to H2 and O2 ...
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