Announcements Mid Term exam Ch 1 4 on October 7 Blackboard grades have been updated Learning Goals for Chapter 4 Define solute solvent which is which Interconvert concentration values based on mass volume and molarity mol L Prepare solutions of the desired molarity Explain the differences between weak strong and non electrolytes and how electrolytes conduct electricity Recognize complete and balance chemical equations describing Acid base neutralization reactions Precipitation reactions Redox reactions Interpret the results of titrations Dilutions Vi Mi Vf Mf This equation works because the number of moles of solute does not change during dilution and Volume L molarity of moles Case 4 Puddle 3 6 L of seawater is trapped in a depression in a rock as the tide goes out Puddle evaporates Vf 2 2 L What is final Na Case 5 Need to prepare 250 0 mL of a 3 18 10 3 M Cu2 solution starting with 0 1000 M stock solution Acids and Bases Acids produce H ions when they dissolve Bases accept those H ions usually by producing OH ions either directly NaOH and Ca OH 2 or indirectly ammonia when they dissolve NH3 g H2O l NH4 aq OH aq Neutralization reactions acid base salt water Inquiry Which of these reactions qualify as an acid base neutralization reaction involve transfer of H ions HCl aq NaOH aq NaCl aq H2O l 2HBr aq CaCO3 s CaBr2 aq H2O l CO2 g CaCO3 s CaO s CO2 g HNO3 aq NH3 g NH4NO3 aq Precipitation Reactions Can happen when solutions of multiply charged positive and negative ions are mixed Other notably insoluble ionic compounds Halides F Cl Br I of Ag Pb2 Hg2 Hydroxides OH of transition metals 2 Which of these reactions is a precipitation reaction CuCl2 aq 2 NaOH aq Cu OH 2 NaCl Ba NO3 2 aq Na2SO4 aq BaSO4 2NaNO3 NaCl aq AgNO3 aq AgCl NaNO3 Reaction in a Zip Lock Bag Calcium chloride baking soda and water CaCl2 aq NaHCO3 aq Writing net ionic equations Focus is on the species in solution that change during the reaction We assume that all ionic solutes separate into their ions
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