Chapter 4 Chemical Quantities and Chemical Reactions
Chapter 4 Chemical Quantities and Chemical Reactions Chem 101
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This 3 page Class Notes was uploaded by Gabrielle Herman on Monday September 26, 2016. The Class Notes belongs to Chem 101 at Ball State University taught by Khisamutdinov in Fall 2016. Since its upload, it has received 5 views. For similar materials see General, Organic, and Biochemistry for the Health Sciences in Chemistry at Ball State University.
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Date Created: 09/26/16
Molecular Mas and Formula Mass Molecular mass o Sum of atomic masses of ions in a molecular formula Unit= amu Formula mass o Sum of atomic masses of ions in a formula unit Conversion: Always go to moles and then convert to desired unit Chemical reaction Bonds are broken and new ones form Properties of new substance are different from starting material Chemical reactions follow the low of conservation of mass o Cant me created or destroyed Will occur if: o The collision occurs with sufficient energy o Substances collide in proper orientation resulting in the breaking and making new bonds Chemical equation: Left side: reactants Right side: products Coefficients o Denotes ration of each reactant to product to the others Physical state o Symbol in parenthesis (s), (g), (l) o Aqueous solution (dissolved in water) (aq) Usually ionic compounds dissolved in water Rules of 7: There are 7 di atomic elements (2 atoms in nature) Balancing chemical equations Count how many atoms of each kind on each side Focus on one element at a time Save the elements that appear as an individual for last If an atom appears more than once on each side of the reaction do those last Don’t change the subscripts on the coefficients Reaction Stoichiometry calculations The study of mole and mass relationship in chemical reactions The coefficients in a blanced chemical equation refer to the number of moles of the compound Energy and Chemical Reactions Chemical reactions involve either the absorption or release of heat energy The first law of thermodynamics states that energy is conserved The change in enthalpy (Delta H) is the heat transferred in a chemical reaction deltaH reaction= deltaH products - deltaH reactants Exothermic reactions o Heat is released Endothermic reaction o Heat is absorbed Calorimetry A technique used to measure deltaH Average caloric content of biomolecules o Carb- 4 o Protein- 4 o Fat- 9 Kinetics: Chemical kinetics o Study of reaction rates, how fast a reaction proceeds Reaction rate can be determined by measuring how much reactant is being consumed over a particular time, or how much product is being made over a particular time. Activation energy o The minimum amount of energy required to convert the reactants to products Factors affecting rate of reaction: Increase the number of collisions between particles Increase the collision energy Give proper orientation to colliding molecules 1. Concentration of reactants and amount of reactants 2. The temperature of reactants o Increasing the temperature will increase the rate of reaction, because more collisions will occur 3. Presence of a catalyst o Any substance that increases the rate of a reaction without being used up o Enzymes are biological catalysts Chemical Equilibrium Many reactions are reversible Reached when the rate of forward reaction is equal to the rate of the reverse reaction The concentration of products and reactants are not equal in a chemical equilibrium Le Chatelier's principle state that when a reaction at equilibrium is disturbed, the reaction responds by shifting in the direction that restores equilibrium A catalyst has no effect on the direction of the equilibrium
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