General Chemistry Chem 1314
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This 4 page Class Notes was uploaded by Morgan Walker on Thursday February 18, 2016. The Class Notes belongs to Chem 1314 at Oklahoma State University taught by Dr. Jimmie Weaver in Winter 2016. Since its upload, it has received 13 views. For similar materials see General Chemistry in Chemistry at Oklahoma State University.
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Date Created: 02/18/16
Chapter 4 & 5 Aqueous Reaction Representation Molecular equation- An equation showing the complete neutral formulas for each compound in the (aq) reaction as if they existed as molecules o 2H 2 O 22H O 2 Complete ionic equation- equations that describe the materials structure when dissolved o 2K + 2OH + Mg +2NO 2K + 2NO + Mg(OH) (s) - 3 3 2 Rules for ionic Aqueous strong electrolytes are written as ions o Soluble salts, strong acids and bases + - 2+ - + - 2K + 2OH + Mg +2NO 2K + 23O + Mg(OH) (s) 3 2 Insoluble substances, weak electrolytes and non-electrolytes are written in molecule form o Solids, liquids and gases are not dissolved + - 2+ - + - 2K + 2OH + Mg +2NO 2K + 3NO + Mg(OH)2(s) 3 Spectator ions Spectator ions don’t change because they don’t participate in the reaction Net ionic equation- ionic equation with the spectator ions have been removed - 2+ o 2OH + Mg + Mg(OH) (s) 2 Neutralization When acids and bases react and salt and water are produced Polyprotic acids Acids containing more than one ionizable proton and releases them sequentially Titration of an Acid Base Titration- when a substance in a solution of known concentration is reacted with another substance of unknown concentration Endpoint- when the reactants are in their stoichiometric ratio o The known is slowly added from a burette o The titrant is the solution in the burette + - Equivalence point- H moles = OH moles o H + OH H O 2 Indicator- dye with different colors in acidic or basic solution, will have a different color after equivalence point Gas Evolving Reactions Some reactions form a gas directly from the ion exchange. o K2S(aq) + H2SO 4aq) H S2 (4q) + H S2g) •Other reactions form a gas by the decomposition of one of the ion exchange products into a gas and water. o NaHCO (3q) + HCl(aq) NaCl(aq) + H CO2(aq3 o H 2O 3aq) H O(2) + CO (g2 Oxidation and Reduction Oxidation and reduction reactions- the reactions when electrons are transferred from one reactant to the other o Also called redox reactions o Many redox involve the reaction of a substance with oxygen Remembering OIL RIG Oxidation Is Loss Reduction Is Gain Reactions of Metals and Non-Metals 4Na(s) + O 2 2Na O 2 This involves a metal reacting with a non-metal, it involves the conversion of free elements into ions Redox reaction The transfer of electrons doesn’t have to be a complete transfer (as occurs in the formation of an ionic compound) for the reaction to be considered to be oxidation-reduction To convert a free element into an ion the atoms must gain or lose electrons o One gains and one loses Oxidation State For non-metal reacting with non-metal without oxygen needs a method for determining how electrons are transferred Chemists assign a number to each element in a reaction called an oxidation state that allows them to determine the electron flow in the reaction o Oxidation state are not ion charges they are imaginary numbers based in rules Oxidation rules 1. Free elements have an oxidation state of 0 a. Na= 0 + Cl 2n 2 Na +Cl 2. Monatomic ions have an oxidation equal to their charge a. Na= +1 Cl=- 1 in NaCl 3. a) sum of oxidation state all atoms in a compound is 0 a. Na= +1 Cl=- 1 (+1) + (-1)=0 b) the sum of all the oxidation state of all the atoms in a polyatomic ion equals the charge of the ion N= +5 + O= -2 in NO 3- (+5) + 3(-2)= -1 4. a) group one metals have oxidation state of +1 in all their compounds a. Na= +1 in NaCl b) group 2 metals have oxidation state of +2 in all their compounds a. Mg= +2 in MgCl 2 5. in their compounds nonmetal have oxidation states according to the table a. nonmetals higher on the table take priority Non-metal Oxidation State Fluorine -1 Hydrogen +1 Oxygen -2 Group 7A -1 Group 6A -2 Group 5A -3 Assigning Oxidation states a) Cl 2 b) SO 4-2 a) Since Cl2is a free element, the oxidation state of both Cl atoms is 0 (rule1). b) O is -2 based on rule 5, S would be -2 but Oxygen has priority so we find S by rule 3 a. S(ox state) + 4 (O ox state) = -2 b. S(ox state) + 4 (-2) = -2 c. S(ox state) = 6 Finding Oxidizing Agents and Reducing agents 2Mg(s) + O (g) 2MgO 2 0 0 2+ -2 This is a redox reaction because Mg increases in oxidation number (oxidation) and oxygen decreases in oxidation number (reduction) Chapter 5 Gases Gases are composed of particles that are moving around very fast in their container(s). These particles move in straight lines until they collide with either the container wall or another particle, then they bounce off. A snapshot of these particles in a gas, will reveal that there is a lot of empty space in there. Force and Pressure Gas particles exert a force when they collide with a surface Result of collisions is pressure Pressure- the force per unit area by gas molecules as they strike the surface around them The total pressure exerted by a gas depends in multiple factors, including the concentration of gas molecules in the sample o Volume increases, concentration of gas molecules decreases Volume increases, concentration of molecules decreases o This results in fewer collisions, which results in lower pressure Variation in pressure in Earth’s atmosphere creates with and changes in pressure o H= high pressure o L= low pressure Number of gas particles in a given volume decreases with increasing altitude o Pressure decreases with increasing altitude ???????????????????? P= ???????????????? Units 1 Pascal (Pa)= 1 N/M 2 1 atm= 760 mmHg 1 atm= 760 torr 1 atm= 101,325 Pa 1 mmHg= 1 torr Boyle’s Law The pressure and volume of a gas are inversely related, at constant mass and temperature
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