BCHM 3050 1st Edition Lecture 3 Outline of Last Lecture I Molecular structure of water II Bonds III Non Polar Covalent bonds IV Polar Covalent bonds V Hydrogen Bonding VI Ionic Bonds VII Van der Waals Forces VIII Water is an ideal biological solvent IX Hydrophobic Effect X Solvent Properties of Water Outline of Current Lecture I Molarity Calculations II Addition of solutes to water increase the boiling point III Addition of solutes to water lowers the freezing point IV Dissociation of NaCl V Osmotic Pressure Calculations VI pH Acids and Buffers VII Ionization of Water VIII pH Calculations Current Lecture I Molarity Calculations a Glucose is a non electrolyte because it doesn t ionize b Molarity M moles liter These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute c Molarity wt grams molecular wt grams x 1000 Vol mL d A 4 g sugar cube sucrose C12H22O11 is dissolved in a 400 ml teacup filled with hot water What is the molarity of the sugar solution i M 4g 342g x 1000 400 0 029M II Addition of solutes to water increase the boiling point a Water has a lot of hydrogen bonds very strong so a lot of energy via high temp is needed to break bonds 100 degrees C b Adding solutes increases the boiling point beyond 100 degrees C because there are added molecular interactions III Addition of solutes to water lowers the freezing point a Decreases freezing point due to more interactions between more molecules needing to be stabilized IV Dissociation of NaCl a Osmotic pressure causes you to throw up when swallow too much sea water increase in solute in stomach b If 100 of solute is dissociated Na and Cl the i value is 1 so 1 1 2 is the dissociation factor V Osmotic Pressure Calculations a Osmotic pressure is expressed by the formula iMRT i is the osmotic pressure in atm ii i van t Hoff factor of the solute iii M molar concentration in mol L iv R universal gas constant 0 08206 L atm mol K v T absolute temperature in K 273 15 temp in Celcius b Anything that doesn t have ionic bonds are non electrolytes c If problem has non electrolytes i 1 d How much glucose C6H12O6 per liter should be used for an intravenous solution to match the 7 65 atm at 37 C osmotic pressure of blood i 765 1 x wt g mol wt g x 1000 vol ml x 0 0206 x 273 37 54 14 g e Calculate the osmotic pressure when 2M NaCl is 90 dissociated in water at 30 0C i Na 0 9 90 dissociated ii Cl 0 9 iii NaCl 0 1 10 undissociated iv i 1 9 v R 0 08206 vi T 273 30 303 vii Pi iMRT 94 48 VI pH Acids and Buffers a The lower the pH the more acidic the solution b Ex Lemon juice red wine c Wine is not an acid just compounds in the item are acids HCl etc d Below 7 pH is acid e The higher the pH the more basic the solution f Ex Baking soda hair remover g Above 7 pH is basic VII Ionization of Water a Ionize water H OH b H2O H OH reversible VIII pH Calculations a acid is a proton donor i strong acids completely dissociate in water ex HCl b base is a proton acceptor i base is anything with a hydroxyl group c the pH scale can be used to measure hydrogen ion concentration i pH log H ii pH pOH 14 d More hydrogen ion concentration the lower the pH e High pH lower hydrogen ion concentration f pOH value that tells you how much OH present g Calculate the pH of 5 X 10 4 M HCl i pH log 5 x 10 4 3 3 h Calculate the pH of 3X10 2 KOH i Calculating pH with the concentration of a base ii pOH 1 52 iii pH 14 1 52 12 48 i At a pH of 3 what is the H concentration of a strong acid i H 10 pH 0 001
View Full Document
Unlocking...