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Chapter 6

BIOL 1107 Chapter Notes - Chapter 6: Vacuum Flask, Endergonic Reaction, Exergonic Reaction

Course Code
BIOL 1107
Thomas Abbot

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6.1 Energy, Life, and the Laws of Thermodynamics
Energy can be converted readily from one form to another
Kinetic energy: energy of an object because it is in motion
Potential energy: stored energy, energy an object has because of its location or chemical structure
Chemical energy: potential energy that can be released in a chemical reaction
Stored in bonds between atoms
Thermodynamics: study of energy and its transformations
Isolated system- does not exchange matter/energy with surroundings
Perfectly insulated thermos flask
Closed system- can exchange energy but not matter with surroundings
Earth takes in energy from Sun and releases heat
Open system- can exchange both energy and matter with surroundings
Living organisms
First Law of Thermodynamics: energy can be transformed from 1 form to another or transferred from 1
place to another, but cannot be created nor destroyed
Conservation of energy
Second Law of Thermodynamics: the total disorder of a system and its surroundings always increases
Entropy: disorder, in thermodynamics
6.2 Free Energy and Spontaneous Reactions
Spontaneous reactions: chemical or physical reactions that occur without outside help
Reactions tend to be spontaneous if the products have less potential energy than the reactants
Enthalpy: potential energy in a system, symbolized by H
Exothermic- reaction that releases energy, products have less potential energy than reactants
Endothermic- reaction that absorbs energy, products have more potential energy than reactants
Reactions tend to be spontaneous when the products are less ordered (more random) than the reactants
Free energy: portion of a system’s energy available to do work, symbolized by G
Change in free energy, ΔG, can be calculated for any chemical reaction by ΔG = ΔH - TΔS
ΔH is change in enthalpy
T is absolute temperature in degrees K
ΔS is change in entropy
ΔG must be negative for reaction to be spontaneous
Often, reactions run in direction of completion (towards reactants or products) till they reach
equilibrium, where reactions are typically reversible
Exergonic reaction: releases free energy, ΔG is negative because products contain less free energy than
Endergonic reaction: products contain more free energy than the reactants, ΔG is positive
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