Chapter 4 Notes: Chemical Quantities and Aqueous Reactions
Chapter 4 Notes: Chemical Quantities and Aqueous Reactions Chem 105
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This 5 page Class Notes was uploaded by Hayley Masterson on Monday September 21, 2015. The Class Notes belongs to Chem 105 at Washington State University taught by Z Heiden in Summer 2015. Since its upload, it has received 34 views. For similar materials see Principles of Chemistry I in Chemistry at Washington State University.
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Date Created: 09/21/15
Hayley Masterson September 12 2015 Chem 4143 Notes 1 41 Climate Change and the Combustion of Fossil Fuels a Without greenhouse gases the average temperature would be 60 F colder 2 42 Reaction Stoichiometry How much carbon Dioxide a b The coef cient 5 in a chemical equation specify the relative amounts in moles of each of the substances involved in the reaction The numerical relationships between chemical amounts in a balanced chemical equation are called reaction stoichiometry 3 43 Limiting Reactant Theoretical Yield and percent Yeild a b Limiting reactant reactant that limits the amount of product in a chemical reaction makes the least amount of product Theoretical yield maximum amount of product that can be made in a chemical reaction based on the amount of limiting reactant Actual yield amount of product actually produced in a chemical reaction Percent yield percentage of the theoretical yield that was actually attained and is calculated as the ratio of the actual yield to the theoretical yield i Actual yieldtheoretical yield100 Hayley Masterson September 13 2015 Chem Notes 4346 1 44 Solution Concentration and Solution Stoichiometry 0qu9 Solution a homogenous mixture of two substances Solvent the majority component of the mixture keeps its state Solute the minority component changes state Aqueous solution one in which water acts as the solvent Solution concentration i Dilute solution solution that contains a small amount of solute relative to the solvent ii Concentrated solution contains a large amount of solute relative to the solvent iii Molarity the amount of solute in moles divided by the volume of the solution in liters Solution Dilution i Stock solutions laboratories often store solution in concentrated forms ii Easiest way to gure out how much stock solution 1 M1V1M2V2 where m1 and v1 are the molarity and volume of the intial concentrated solution and m2 and v2 are the nal solution Solution Stoichiometry i Volume A to Amount A in moles to Amount B in moles to Volume B ii END OF MATERIAL FOR QUIZ 2 45 Types of Aqueous Solutions and Solubility a When a solid is put into liquid solvent the attractive forces that hold the solid together compete with the attractive forces between the solvent molecules and the particles that compose the solid b Electrolyte and Nonelectrolyte Solutions i Electrolytes substances that dissolve in water to form solutions that conduct electricity ii Strong electrolytes substances that completely dissolve into ions when they dissolve in water ionic compounds and strong acids iii Most molecular compounds besides acids dissolve in water as intact molecules iv Nonelectrolytes compounds such as sugar that do not dissociate into ions when dissolved in water does not conduct electricity v Strong Acid one that completely ionizes in a solution HCl and are strong electrolytes with a single reaction arrow C vi Weak acids do not completely ionize in water and this has opposing half arrows also classi ed as weak electrolytes and conduct electricity weakly The solubility of Ionic Compounds when ionic compounds dissolve in water the anions and cations are separated caed dissociation i Soluble if dissolves in water ii Insoluble if it doesn39t dissolve in water iii Compounds with sodium Na are soluble and compounds with NO3 and C2H302are soube iv Compounds with CO32 are insoluble but they are soluble when paired with Li Na K or NH4 v Cl Br and I are soluble except when with Ag HgZ or Pb 3 46 Precipitation Reactions a b When a solid or precipitate forms when two solutions are mixed Only insoube compounds form precipitates if both insoube no reaction occurs No precipitation means no reaction even is both souabe Hayley Masterson September 13 2015 Chem 105 Notes sec 4749 1 47 Representing Aqueous Reactions Molecular Ionic and Complete Ionic Equanns a Molecular equation an equation showing the complete neutral formulas for each compound in the reaction as if they existed as molecules b Complete Ionic equations list all of the ions present as either reactants or products in a chemical reason c Spectator ions some of the ions in the solution appear unchanged on both sides of the equation omit these to show more clearly what is happening d Net ionic equations equations that show only the species that actually change during the reaction 2 48 AcidBase and GasEvolution Reactions a Acidbase reactions neutralizing reaction an acid reacts with a base and the two neutralize each other producing water b Gasevolution reaction a gas forms resulting in bubbling c AcidBase Reactions i Arrhenius De nitions 1 Acid substance that produces H ions in aq solution 2 Base substance that produces OH ions in aqueous solution ii Hydronium ions bare protons H associate with water molecules to form iii Polyprotic acids contain more than one ionizable proton and release them sequentially H2504 is a diprotic acid strong in HSO4 but weak in SO42 iv Diprotic base forms two moles of OH per one mole base v Salt ionic compound formed from acidbase remains dissolved in the solution vi Acid base results in water salt d Titration a substance in a solution of known concentration is reacted with another substance in a solution of unknown concentration e Equivalence point the point in the titration when the number of moles of OH added equals the number of moles of H in a solution f Indicator a dye whose color depends on the acidity or basicity of the solution g GasEvolution Reactions i Two aqueous solutions mix to forma gaseous product that bubbles out of solution ii Sometimes an intermediate product forms that breaks down to form gas 3 49 oxidationreduction reactions a Oxidationreduction reactions redox reactions reactions in which electrons transfer from one reactant to the other rusting of iron bleaching of hair and production of electricity in batteries Do not need to involve oxygen Oxidation the loss of elections Reduction the gain of electrons Oxidation states i Oxidation state or oxidation number the charge it would have if all shared electrons were assigned to the atom with the greatest attraction for those elements ii HCI H lost an electron has oxidation state 1 and CI has oxidation state of 1 gained an electron The ionic charges are written after the chemical symbol and oxidation states are written before f Rules for assigning states i The oxidation state of an atom in a free element is 0 ii The oxidation state of a monoatomic ion is equal to its charge iii The sum of the oxidation states of all atoms in 1 A neutral molecule or formula unit is 0 H20 2 An ion is equal to the charge of the ion NO3 iv In their compounds metaIs have positive oxidation states 1 Group 1A metals always have an oxidation state of 1 NaCl 2 Group 2A metals always have an oxidation state of 2 CaF2 v In compounds nonmetas are assigned oxidation states according to the table at the right Entries at the top of the table take precedence over entries at the bottom g Identifying Redox Reactions i C25 yields C52 ii C is oxidized and S is reduced 0 0 yields 4 2 S gained electrons iii Oxidation and reduction must occur together iv Oxidizing agent a substance that causes the oxidation of another substance v Reducing agent a substance that causes the reduction of another substance 1 Hydrogen and group 1A and 2A metals are good reducing agents h Combustion Reactions i Characterized by the reaction of a substance with 02 to form one or ore oxygen containing compounds often including water and emitting heat ii Compounds containing carbon and hydrogen andor oxygen aways form carbon dioxide and water upon complete combustion DQ00
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