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Unformatted text preview: Chapter 2 Chemistry Introduction to Chemical Reactions Reactants - Materials going into a reaction Products - Materials coming out of a reaction Metabolism - All of the reactions that are occurring at one time Chemical Reactions Basic Energy Concepts Energy - The power to do work Work - A change in mass or distance Kinetic energy - Energy of motion Potential energy - Stored energy Chemical energy - Potential energy stored in chemical bonds a. Decomposition reaction (catabolism) - Breaks chemical bonds AB A + B Hydrolysis: ABCDE + H 2 O ABCH + HODE b. Synthesis reaction (anabolism) - Forms chemical bonds A + B AB Dehydration synthesis (condensation) ABCH + HODE ABCDE + H 2 O c. Exchange reaction - Involves decomposition first, then synthesis AB + CD AD + CB d. Reversible reaction - A reaction that occurs simultaneously in both directions AB A + B At equilibrium the amounts of chemicals do not change even though the reactions are still occurring: 0. Reversible reactions seek equilibrium, balancing opposing reaction rates 1. Add or remove reactants: reaction rates adjust to reach a new equilibrium Enzymes - chemical reactions in cells cannot start without help; Activation energy is the amount of energy needed to get a reaction started Enzymes are protein catalysts that lower the activation energy of reactions a. Exergonic ( exothermic ) reactions - Produce more energy than they use b. Endergonic ( endothermic ) reactions - Use more energy than they produce Inorganic Versus Organic Compounds Nutrients - Essential molecules obtained from food Metabolites - Molecules made or broken down in the body Inorganic - Molecules not based on carbon & hydrogen Carbon dioxide, oxygen, water, and inorganic acids, bases, and salts Organic - Molecules based on carbon & hydrogen Carbohydrates, proteins, lipids, nucleic acids Importance of Water - Water accounts for up to two-thirds of your total body weight A solution is a uniform mixture of two or more substances; it consists of a solvent , or medium, in which atoms, ions, or molecules of another substance, called a solute , are individually dispersed a. Solubility - Waters ability to dissolve a solute in a solvent to make a solution b. Reactivity - Most body chemistry occurs in water c. High heat capacity - Waters ability to absorb and retain heat d. Lubrication - To moisten and reduce friction The Properties of Aqueous Solutions i. Ions and polar compounds undergo ionization, or dissociation in water ii. Polar water molecules form...
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