7 Equations for Solution Formation When NaCl(s) dissolves in water, the process can be written as:H2ONaCl(s) Na+(aq) + Cl- (aq)solid separation of ionsThe Na+ ions are attracted to the oxygen atom ( -) of water.The Cl- ions are attracted to the hydrogen atom (+) of water.
8 Like Dissolves Like Two substances form a solution When there is an attraction between the particles of the solute and solvent.When a polar solvent such as water dissolves polar solutes such as sugar and ionic solutes such as NaCl.When a nonpolar solvent such as hexane (C6H14) dissolves nonpolar solutes such as oil or grease.
13 Strong Electrolytes Strong electrolytes Dissociate in water producing positive and negative ions.Conduct an electric current in water.In equations show the formation of ions in aqueous (aq) solutions.H2O % ionsNaCl(s) Na+(aq) + Cl− (aq)H2OCaBr2(s) Ca2+(aq) + 2Br− (aq)
14 Weak Electrolytes A weak electrolyte Dissociates only slightly in water.In water forms a solution of only a few ions and mostly undissociated molecules.HF(g) H2O(l) H3O+(aq) + F- (aq)NH3(g) + H2O(l) NH4+(aq) + OH- (aq)Note: Unequal lengths of the arrows
17 Solubility Solubility Is the maximum amount of solute that dissolves in a specific amount of solvent.Can be expressed as grams of solute in 100 grams of solvent, usually water.g of solute100 g water
26 Equations for Forming Solids A molecular equation shows the formulas of thecompounds.Pb(NO3)(aq) + 2NaCl(aq) PbCl2(s) + 2NaNO3(aq)An ionic equation shows the ions of the compounds.Pb2+(aq) + 2NO3−(aq) + 2Na+(aq) + 2Cl−(aq)PbCl2(s) + 2Na+(aq) + 2NO3−(aq)A net ionic equation shows only the ions that form asolid. Ions remaining in solution are spectator ions.Pb2+(aq) + 2Cl−(aq) PbCl2(s)
27 Equations for the Insoluble Salt STEP 1 Observe the ions in the reactants.Pb2+(aq) + 2NO3−(aq)2Na+(aq) + 2Cl−(aq)STEP 2 Determine if any new ion combinations areinsoluble salts. Yes. PbCl2(s)STEP 3 Ionic equation with insoluble salt product.Pb2+(aq) + 2NO3−(aq) + 2Na+(aq) + 2Cl−(aq)PbCl2(s) + 2Na+(aq) + 2NO3−(aq)STEP 4 Net ionic equation.Pb2+(aq) + 2Cl−(aq) PbCl2(s)
31 Calculation of Molarity What is the molarity of L NaOH solution if itcontains 6.00 g NaOH?STEP 1 Given g NaOH in L solutionNeed molarity (mol/L)STEP 2 Plan g NaOH mol NaOH molaritySTEP 3 Conversion factors 1 mol NaOH = g1 mol NaOH and g NaOH40.00 g NaOH mol NaOH
32 Calculation of Molarity (cont.) STEP 4 Calculate molarity.6.00 g NaOH x 1 mol NaOH = mol40.00 g NaOH0.150 mol = mol = M NaOH0.500 L L
34 Molarity in Calculations How many grams of KCl are needed to prepare125 mL of a M KCl solution?STEP 1 Given mL (0.125 L) of M KClNeed Grams of KClSTEP 2 Plan L KCl mol KCl g KCl
35 Molarity in Calculations (cont.) STEP 3 Conversion factors1 mol KCl = g1 mol KCl and g KCl74.55 g KCl mol KCl1 L KCl = mol KCl1 L and mol KCl0.720 mol KCl LSTEP 4 Calculate grams.0.125 L x mol KCl x g KCl = 6.71 g KCl1 L mol KCl
37 Comparing Initial and Diluted Solutions In the initial and diluted solutionThe moles of solute are the same.The concentrations and volumes are related by the equationM1V1 = M2V2initial diluted
38 Dilution Calculations What is the molarity if L of M KOH isdiluted to a final volume of L?STEP 1 Prepare a table:M1= M V1 = LM2= ? V2 = LSTEP 2 Solve dilution equation for unknown.M1V1 = M2V2 M1V1/ V2 = M2STEP 3 Set up and enter values:M2 = M1V1 = (0.600 M)(0.180 L) = MV L