I. Importance of H2O:Important in living thingsBegan life – organisms made up of mostly waterWater covers ¾ Earth’s surfaceMajor reason that we have life on the planetII. Unusual behavior of water is caused by:Hydrogen bonds:Polar covalent bonds between O and Hδ+ charge on Hδ- charge on OWater is attracted to water molecules and other polar or charged molecules because of charge attractionsThis unusual behavior is an example of EMERGENT PROPERTIES (one of the unifying themes of bio – lecture 1)III. Unusual properties of H2O:High specific heat – amount of heat (in calories) that is required to increase the temperature of a substance by 1°CDoesn’t easily change temperatureHeat breaks hydrogen bonds before it increases temperatureIf you take out the heat to cool water down, the temperature doesn’t change, hydrogen bonds formBiological significance:Living things resist temperature changeStabilizes ocean temperatureExpands when it freezes:Ice is less dense than water  ice floats on waterNot usually the case with other substancesCaused by hydrogen bondsIn liquid form, hydrogen bonds form and break often (dynamic, move a lot)At 0°C, the molecules no longer move to break and form hydrogen bondsBiological significance:i. Floating ice insulates the water below  prevents the water from freezing solid  keeps organisms in water aliveWater is the biological solvent:Solution – liquid that is a homogenous mix of two or more substances; made of:Solute – substance that is dissolvedSolvent – liquid that dissolves the substanceA cell is like a drop of water with many solutes in itThe properties of water as a solvent are due to the hydrogen bondingGreat solvent for solutes that are charged or polar because water is POLARi. Ex: NaCl (table salt) – easily dissolved in water, H2O molecules pull the 2 ions apart and surround themNonpolar substances do NOT dissolve in water – polar and nonpolar substances do NOT mixi. Ex: H2O and oil don’t mix; water = polar, oil = nonpolarIV. Properties of Aqueous Solutions:Aqueous solutions - H2O is the solventCells are aqueous solutions so it’s important to know these 2 properties:Solute Concentration – the number of molecules in a given amount of solutionTerms to know:Mole – number of grams of a substance equal to its molecular weight; to find moles: grams of the substance/substance’s molecular weightMolecular weight – sum of the atomic masses of each atoms in the moleculeMolar (M) – number of moles of a solute in one liter (L) in a solution [molarity]The concentration of substances is given in terms of Molarity because one mole of any substance has the SAME number of MOLECULES as one mole of anything else:Avagadro’s number = 6.02 × 1023V. Acids, Bases, and pHH2O can disassociate, rarely happens, but important because small changes in H+ and OH- can cause dramatic changes in the ability of biological molecules to function  gives Oxygen a full negative charge from the electron that Hydrogen leaves behind when they disassociatePure H2O has H+ and OH- as equal, aka in balanceWhen acids and bases dissolve in water, the balance of H+ and OH- is shiftedPure H2O  [H+] = [OH-] = 10-7Acids ADD [H+] to the solutionBases REDUCE [H+] (holds [H+] or donates [OH-])In an aqueous solution:i. [H+] [OH-] = 10-141. If one goes down, the other must go up to maintain the product of 10-14ii. If you know the concentration of one, you can use the formula to find the other.pH scale – scale that measures the degree of acidity on a scale of 0-14ii. Mathematically  pH = -log[H+] **question on first exam**iii. pH < 7  acidiciv. pH = neutral (pure water)Hydrogen = 10-7pH = -log[-7]  7v. pH > 7  basicvi. Each unit of pH represents a 10-fold change in [H+]vii. Most biological fluids maintain a pH of between 6 and 8Equations to help with pH:ii. pH = -log[H+]iii. pOH = -log[OH-]iv. [H+][ OH-] = 10-14v. pH + pOH = 14VI. Solute Concentration Problems:1. How many grams of glucose (C6H12O6) are in 1 Mole of glucose?2. How many moles of glucose (C6H12O6) are in 1 Liter of a 1M solution of glucose? How many moles of glucose are in 1 Liter of a 2M solution of glucose? How many molecules are in each of these solutions?3. You have 1 Liter of a 1M solution of glucose (C6H12O6). How many moles of fructose (C5H10O5) would you need to have an equal amount of glucose and fructose molecules?4. How many grams of C4H10 are in one mole of C4H10? How many molecules of C4H10 are in one mole of it?5. How would you make a 1M solution of C4H10?VII. Solute Concentration Solutions:1. C  12g, H  12g, O  16g6(12)+12(1)+6(16)=180g/mol2. 1 mole of glucose in 1M solution; 6.02×1023 molecules of glucose2 moles of glucose in 2M solution; 1.204×1024 molecules of glucose3. 1 mole of fructose4. C  12g, H  1g4(12)+10(1)=58g/mol6.02×1023 molecules of C4H105. Dissolve 58 grams of C4H10 in some water, and then once it has dissolved, add more water until the solution is equal to 1 Liter.VIII. pH Problems:1. What is the mathematical definition of pH?2. What is the pH of a solution that has [H+]=10-5M?3. If a solution has a pH of 5, what is the [H+]? What is the [OH-]?4. If a solution has a pH of 4, what is the pOH?5. The pH of a solution is increased from 6 to 7. Is the [H+] increased or decreased? By how much?6. The pH of a solution is increased from 6 to 7. Is the [H+] increased or decreased? By how much?IX. ph Solutions:1. pH=-log[H+]2. pH=-log[H+]pH=-log[10-5]pH=53. pH=-log[H+]5=-log[H+]10-log(H+)=10-5[H+]=10-5[H+][OH-]=10-1410-5[OH-]=10-14[OH-]=10-94. pH+pOH=144+pOH=14pOH=105. The [H+] is decreased.It is decreased by 10.6. [10-9] [H+]=10-14[H+]=10-5pH=-log[H+]pH=-log[10-5]pH=5Lecture 3 Outline of Last Lecture I. MatterII. Structure and Behavior of AtomsIII. Electrons and Energy LevelsIV. Chemical BondsV. Chemical ReactionsOutline of Current Lecture I. Importance of WaterII. Causes of Unusual Behaviors of WaterIII. Unusual Properties of WaterIV. Aqueous Solutions and Their PropertiesV. Acids, Bases, and pHVI. Solute Concentration EXTRA CREDIT HW Problems VII. Solute Concentration EXTRA CREDIT HW SolutionsVIII. pH EXTRA CREDIT HW ProblemsIX. pH EXTRA CREDIT HW SolutionsX. QUIZ THURSDAY IN CLASSCurrent LectureI. Importance of H2O:- Important in living things- Began life – organisms made up of mostly water- Water covers ¾ Earth’s surface- Major reason that we have life on the planetII. Unusual behavior of water is caused by:- Hydrogen