Chemistry 11 Solution Chemistry Unit Notes Unit 9 Solution Chemistry Solution: ________________________________________________________________ Solvent:__________________________________________________________________ Solute:__________________________________________________________________ A solute is soluble in a solution if _______________________________________ A solvent is saturated with a solute if ____________________________________ A solvent is unsaturated with a solute if __________________________________ the solubility of a solute is ______________________________________________ _________________________________________________________________________ Solvation: ________________________________________________________________ Ionic solid:_______________________________________________________________ Molecular solid:___________________________________________________________ Electrolytic Solution: ______________________________________________________ Does the amount of solid in a saturated solution increase, decrease or stay the same if… and explain why. Increase the temperature Increase the temperature in a closed container then allow it to cool back to room temperature Decrease the temperature Leave the container uncovered overnight Shanghai Nanyang Model High School -1- Chemistry 11 Solution Chemistry Unit Notes 1. CONDUCTIVITY Solids :________________________________________________________ Pure Liquids:___________________________________________________ ______________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Which compounds will dissolve to from ionic solutions? 1) 2) 3) Need water for conductivity – otherwise ions not dissociated How To determine if a substance will conduct electricity Shanghai Nanyang Model High School -2- Chemistry 11 Solution Chemistry Unit Notes 2. MOLECULAR POLARITY Dipole:___________________________________________________________________ Electropositive: atoms with ______________________tend to form ___________ ions Electronegative: atoms with ______________________tend to form ___________ ions London Forces: ___________________________________________________________ ________________________________________________________________________ A. Non-polar molecules ___________________________ eg) BF3 , CH4 F H F H C B F H H Have a __________________ B. Polar Molecules to be polar, molecules: must be _____________________ (dissimilar ends) one end _______________________ than other end δO dipole moment H H δ+ Shanghai Nanyang Model High School -3- Chemistry 11 Solution Chemistry Unit Notes C. Dipole-Dipole Forces ___________________________________________________________________ eg) water: δ- δ- O O H H H H δ+ δ+ D. Hydrogen bonding ___________________________________________________________________ ___________________________________________________________________ ______________________________________________( between different NH3 ’s) ___________________________________________________________________ ___________________________________________________________________ (Explains high BP of water) The electronegative atom must have one or more _____________ electron pairs as in the case of oxygen, flurine and nitrogen, and has a negative partial charge. The hydrogen, which has a partial _____________ charge tries to find another atom of oxygen or nitrogen with excess electrons to share and is ________________ to the partial negative charge. This forms the basis for the hydrogen bond. E. Physical Properties of Water Related with Intermolecular Forces For most substances, solids are more dense than liquids. This is not true for water. Water is _______ dense as a solid ice floats on liquid water! Strong hydrogen bonds formed at freezing lock water molecules away from each other. Shanghai Nanyang Model High School -4- Chemistry 11 Solution Chemistry Unit Notes When ice melts, the structure collapses and molecules move closer together. This property plays an important role in lake and ocean ecosystems. Floating ice often ______________ and ________________ animals and plants living in the water below. Using Diagrams Compare the Structure of Ice Water to Liquid Water F. Polarity and Boiling Point: Review The polarity of the molecules determines the forces of attraction between the molecules in the liquid state. Polar molecules are attracted by the opposite charge effect (the positive end of one molecule is attracted to the negative end of another molecule. Molecules have different degrees of polarity as determined by the functional group present. The evidence for hydrogen bonding Many elements form compounds with hydrogen - referred to as ____________. If you plot the boiling points of the hydrides of the Group 14 elements, you find that the boiling points _______________ as you go down the group. Explain Why this happens:___________________________________________ __________________________________________________________________ __________________________________________________________________ Shanghai Nanyang Model High School -5- Chemistry 11 Solution Chemistry Unit Notes Although for the most part the trend is exactly the same as in group 4 (for exactly the same reasons), the boiling point of the hydride of the first element in each group is abnormally high. In the cases of NH3, H2O and HF there must be some additional _________________________ forces of attraction, requiring significantly more ______________________________ to break. These relatively powerful intermolecular forces are described as _______________________ ________________________ The origin of hydrogen bonding The hydrogen is attached directly to one of the __________ _________________ elements, causing the hydrogen to acquire a significant amount of _____________ ___________________ Each of the elements to which the hydrogen is attached is not only significantly negative, but also has at least one "active" lone pair. Lone pairs at the 2-level have the electrons contained in a relatively small volume of space which therefore has a high density of negative charge. Lone pairs at higher levels are more diffuse and not so attractive to positive things. Shanghai Nanyang Model High School -6- Chemistry 11 Solution Chemistry Unit Notes 3. Nature of IONS IN SOLUTION A. Polar and non Polar solvents Polar solvents:____________________________________________________________ ______________________________________________________________________ Non – polar solvents:______________________________________________________ ______________________________________________________________________ B. Choosing a solvent Like-dissolves-like _______________ solvents tend to dissolve ___________ or _________ solutes. __________________ solvents tend to dissolve __________________ molecules. Polar solvents ___________________________________________________________________ ____________ ___________ are attracted by _______________ ____________. _____________________________________________. __________________________________________________________________. are not attracted by _______________________________. __________________________________________________________. Polar solvents will dissolve: _____________________________________ _____________________________________ _____________________________________ Shanghai Nanyang Model High School -7- Chemistry 11 Solution Chemistry Unit Notes Non-Polar solvents Tend not to have no _____________________________ dissolve do not attract __________________________ attract non-polar solutes ____________________________________________. Do question 17 pg 205 and then draw and name two polar and two non-polar solvents Polar solvents Non Polar solvents 1. 1. 2. 2. 4. The nature of SOLUTIONS OF IONS Dissociation: _____________________________________________________________ ________________________________________________________________________ Dissociation Equation: _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Shanghai Nanyang Model High School -8- Chemistry 11 Solution Chemistry Unit Notes A. Dissolving salts __________________________________________________. eg) NaCl _____________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ B. Dissolving organic acid/alcohol Ionization: __________________________________________________________________ eg) CH3COOH(l) _________________ + ____________________ Writing dissociation and ionization equations: _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Homework: pg. 207 # 18 – 22 Shanghai Nanyang Model High School -9- Chemistry 11 Solution Chemistry Unit Notes 5. Calculating Ion Concentrations in Soluiton Concentration = ________________ = if there no Volume is given…..assume 1 L. eg1) What is the concentration of the Cl- in 0.75 M AlCl3(aq)? 1) ________________________________________________________________ 2) ________________________________________________________________ AlCl3(aq) (aq) + (aq) [Cl-] = = eg2) What is concentration of each ion produced by mixing 200 mL of 0.355 M AlBr3 and 250 mL of 0.300 M CaBr2 1) ________________________________________________________________ 2) ________________________________________________________________ 3) ________________________________________________________________ a) for AlBr3 AlBr3 + [AlBr3]f = [Al3+] f = [Br-] f = Shanghai Nanyang Model High School - 10 - Chemistry 11 Solution Chemistry Unit Notes CaBr2 b) for CaBr2 + [CaBr2] f = [Ca2+] f = [Br-] f = Add up the concentrations of similar ions [Al3+] = ___________________ [Ca2+] = ___________________ [Br-] = __________________________________ 6. pH A. Self- ionization of water H2O ionizes into H+ and OH- ions. H3O+ H2O(l) + H2O(l) (aq) + …..molecular representation: Shanghai Nanyang Model High School - 11 - (aq) Chemistry 11 Solution Chemistry Unit Notes Only a very small amount of water self-ionizes at 25 °C in pure water: [H3O+] = _________________M [OH-] = __________________ M Ion Product of water (Kw) Kw = [ ][ ] ][ ] Or Kw = [ In pure water at 25 °C [ ]=[ ]= + = [H3O ] [OH-] = Kw = (Kw has no units) B. Calculating [H3O+] and [OH-] ___________________________________________________________________ ___________________________________________________________________ Example: If [H3O+] in a solution is 1.0 · 10-2 M, then [OH-] will be 1.0 · 10-12 M. Kw = [H3O+] [OH-] = 1.0 · 10-14 Solve for [OH-] [OH-] = Kw [ H 3O ] = [OH-] = Shanghai Nanyang Model High School - 12 - Chemistry 11 Solution Chemistry Unit Notes Note: ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ C. Acidic, Basic, or Neutral Solutions Acidic: ________________________________________________________________ Basic: ________________________________________________________________ Neutral: ______________________________________________________________ eg) If the [H3O+] (or [H+]) in blood is 4.0 · 10-8 M, what is the [OH-] at 25 °C? Is blood acidic, basic or neutral. Kw = [H3O+] [OH-] = 1.0 · 10-14 [H3O+] = 4.0 · 10-8 M Solve for [OH-] [OH-] = Kw [ H 3O ] = = Since [H3O+] = Or [OH-] = Blood is __________________________ Practice Problems: Do on a separate piece of paper 1) What is the [OH-] in chocolate milk if [H3O+] = 4.5 · 10-7 M? Is chocolate milk acidic or basic or neutral. 2) What is the [H3O+] in black coffee if [OH-] = 1.3 · 10-9 M. Is black coffee acidic, basic, or neutral? Shanghai Nanyang Model High School - 13 - Chemistry 11 Solution Chemistry Unit Notes D. The pH Scale ___________________________________________________________________ ___________________________________________________________________ pH = or pH = or pOH = pH = Example: In one brand of vegetable juice, [H3O+] = 7.3 · 10-5 M. What is the pH of the juice? pH = = On your calculator: 1) 2) 3) 4) 5) 6) pH = pH and Significant figures. ___________________________________________________________________. eg) [H3O+] = Shanghai Nanyang Model High School - 14 - Chemistry 11 Solution Chemistry Unit Notes pH = E. pH and pOH scale @25oC More Acidic pH 0 1 2 [H3O+] 1 10-1 10-2 [OH-] pOH 3 4 Neutral 5 6 More Basic 7 8 9 10 11 12 13 14 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14 10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Conversion Picture: Kw = pH = pOH = pH + pOH = Practice problems: 1) Normal rainwater has a pH near 6. In rain near a coal – burning power plant, [H3O+] = 6.23 · 10-4 M. What is the pH of this rainwater? 2) In household bleach, [OH-] = 5.0 · 10-2 M. What is the pH of household bleach? Shanghai Nanyang Model High School - 15 - Chemistry 11 Solution Chemistry Unit Notes F. Acid Base Titrations Remember from unit 7: In a titration the molarity of one chemical is determined by reacting it with another one with known molarity (standard). 1. 6.50 mL of 0.100 M H2C2O4 is required to neutralize 10.0 mL of KOH solution in a titration. Calculate the base concentration. H2C2O4 + 2KOH K2C2O4 + 2H2O If you get data in a table, you need to subtract the final burette reading from the initial to get the volume of acid or base added. If you have multiple trials, average them but reject any volumes that are way off. Use some common sense. Burette Volume in mL Initial 0.00 mL Final 8.95 mL Volume Added Shanghai Nanyang Model High School 8.95 mL 17.41mL - 16 - 17.41 mL 25.85 mL Chemistry 11 Solution Chemistry Unit Notes 2. 8.95 mL , 8.46 mL and 8.44 mL of 0.200 M H2SO4 was required to neutralize 25.0 mL of KOH solution in a titration. Calculate the base concentration. 3. Calculate the mass of H2C2O4.2H2O required to make 100.0 mL of a 0.1000 M standard solution to use in your titration lab tomorrow. Shanghai Nanyang Model High School - 17 - Chemistry 11 Solution Chemistry Unit Notes G. ‘ICE’ charts with Acid Base Reactions: For reactions with Excess acids or bases 1. 250.0 mL of 0.100 M H2SO4 reacts with 600.0 mL of 0.0500 M NaOH. Calculate the concentration of the excess acid or base. Step 1: Complete the balanced reaction equation Step 2: Build the ICE table (I = Initial, C = Change, E = Equilibrium or End) I C E Shanghai Nanyang Model High School - 18 - Chemistry 11 Solution Chemistry Unit Notes 2. 300.0 mL of 0.100 M H2SO4 is mixed with 100.0 mL of 0.650 M NaOH , calculate the concentration of the excess acid or base? I C E The two solutions are mixed therefore you need to ______________________________ to get the molarity! The new volume = [NaOH] = Shanghai Nanyang Model High School - 19 -