CONDENSED STATES Chemistry Spring 2015 AGENDA 3/2/15 Hard Boiled Egg?? Tests Back? Learning Targets for Unit 3 Review from 1st Semester Notes over the review Topics HW: Complete the Phase Change Graphic **Tomorrow TESTING DAY** ENERGY AND PHASES REVIEW Potential vs Kinetic E a. PE = stored energy 1. Breaking bonds increases PE Making bonds releases PE b. KE = E of motion KEgas > KEliquid > KEsolid 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 3 ENERGY AND PHASES REVIEW 2. Exothermic vs Endothermic a. Exothermic Gives off E (E is released to surroundings) Bond formation Gas liquid solid (“intermolecular force formation”) Why? I am forming bond, making things more stable – energy is released. 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 4 ENERGY AND PHASES REVIEW b. Endothermic Absorbs E (E taken from surroundings) Bonds breaking Solid liquid gas (“intermolecular force breaking”) Why? Energy is needed to break bonds. **BARF** Break, absorb, release, form 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 5 ENERGY AND PHASES REVIEW Solid sublimation melting deposition freezing Liquid condensation Gas evaporation 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 6 ENERGY AND PHASES REVIEW Inside Arrows: Exothermic (feels hot) Decreases PE Forming IM forces More order Particles closer 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 7 ENERGY AND PHASES REVIEW Outside Arrows Endothermic (feels cold) Increases PE Breaking IM forces Less order Particles spread out 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 8 ENERGY AND PHASES REVIEW 3. Heat vs Temperature a. Heat Form of energy Measured in Joules (J) kJ (1000 J) Flows from warmer object to colder object 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 9 ENERGY AND PHASES REVIEW b. Temperature Measure of average KE of particles How much particles are moving E given to particles increase motion increase T Measuring Temperature Celsius vs Kelvin 2 different temperature scales K is a more direct reflection of KE 3/10/2016 copyright www.brainybetty.com 2006 All Rights Reserved 10 ENERGY AND PHASES REVIEW Kelvin (K) -273oC 0K Freezing point of water 0 oC 273 K 100oC 373 K Boiling point of water Remember: K = C + 273 copyright www.brainybetty.com 2006 All Rights Reserved Absolute zero 3/10/2016 Celsius (oC) 11 AGENDA 3/4/15 Hand Back Unit 2 Tests 5 Minute Remediation Notes on Solutions and Solubility Solubility Curves Pre-Lab for Solubility Lab Tomorrow HW: Complete Solubility Curve WS SOLUTIONS Solutions Free template from www.brainybetty.com Homogeneous mixture is the same throughout Stable won’t spontaneously separate Examples: Kool-Aid, saltwater, pop Made of 2 parts: Solute – chemical that is dissolved (Kool-Aid mix) Solvent – chemical that does the dissolving (water) 3/10/2016 13 SOLUTIONS Aqueous Solution – a solution where H2O is the solvent Why do things dissolve? Molecule – Ion Attraction Similar chemical structure 3/10/2016 Free template from www.brainybetty.com 14 SOLUTIONS NaCl (s) H Na+ (aq) + - + - - + - + + - + - O H H H O H O O H H H O + H O H H H 3/10/2016 Free template from www.brainybetty.com 15 SOLUTIONS NaCl (s) + - + - - + - + - + - Na+ (aq) + H H O H H O H H O - H H O O H 3/10/2016 Cl- (aq) H Free template from www.brainybetty.com H O H 16 SOLUTIONS Solvation Occurs on the surface of a solid May be exothermic or endothermic Heat of Solution – energy change caused by dissolving Ex: acid in water is warm 3/10/2016 Free template from www.brainybetty.com 17 AGENDA 3/5/15 Finish notes on Solutions and Solubility Solubility Lab of Ammonium Chloride Solubility Curves Examples of Solubility Curves Notes on Molarity Practice Problems HW: Complete Solubility Lab WARM-UP What is a solute? What is a solvent? What are three ways to dissolve solids faster? Explain solvation to your partner. How do you get things to dissolve faster? SOLUTIONS Factors that affect the rate of solvation: 1. Stirring – fresh solvent is brought to surface of solute (faster) 2. Increase T – solvent molecules have more KE (faster) 3. Surface area – powder dissolves faster than a chunk 3/10/2016 Free template from www.brainybetty.com 21 SOLUTIONS *LIKES DISSOLVE LIKES* water & food coloring “miscible” 2 substances are alike and will mix water & oil “immiscible” 2 substances are different and will not mix 3/10/2016 Free template from www.brainybetty.com 22 SOLUBILITY LAB Safety: Do not reach over the hot plate Tips: Heat the test tube in the water very gently Use the distilled water in the test tube only Use tap water in the beaker Make sure you know the amount of Ammonium Chloride your group is responsible for. AGENDA 3/6/15 Wrap-Up Solubility Lab What does it mean? Notes on Solubility Curves Saturation/Super-Saturation Practice Problems with Solubility Notes on Molarity Practice Problems HW: Complete Solubility WS SOLUBILITY LAB What was the solubility of Ammonium chloride at 55 degrees C? What would the solubility be at 85 degrees C? What would the solubility be at 35 degrees C? What does our best-fit line tell us about the solubility of Ammonium chloride? Solubility – the maximum amount of solute that can be dissolved in a given amount of solvent SOLUBILITY CURVES Solid in Liquid Solutions - 3 “stages” Unsaturated 1. • • Contains less than the maximum amount of solute All solute dissolves and there is room for more SOLUBILITY CURVES 2. Saturated maximum amount of solute is dissolved additional solute will not dissolve at that T depends on T occurs when rate of dissolving = rate of crystallization SOLUBILITY 3. Supersaturated more solute dissolved than the solution would normally hold can make by carefully cooling a saturated solution unstable, wants to crystallize SOLUBILITY = dissolving Sugar cube dissolving in H2 O = crystallizing Some dissolves Some crystallizes Solution is saturated! Equilibrium dissolving = crystallization AGENDA 3/9/15 Review Solubility Check HW Notes on Molarity Practice Problems with Molarity HW: Complete Molarity WS SOLUTIONS WARM-UP Explain the following terms: Unsaturated Saturated Supersaturated How do we measure the amount of solute in a solvent? Concentration – the amount of solute dissolved in a given amount of solvent Dilute – small amount of solute (weak) Concentrated – a lot of solute (strong) MOLARITY Molarity A unit of concentration # of moles of solute per 1 L of solution Molarity (M) = moles of solute = Liters of solution mol L MOLARITY Examples: A salt solution has a volume of 152 mL and contains 0.90 mol NaCl. What is the molarity of the solution? MOLARITY M = mol L 152 mL = 0.152 L M = 0.90 mol 0.152 L = 5.9 M MOLARITY A 3.0 L aqueous solution contains 45.0 g KI. What is the solution’s molarity? 45.0 g KI 1 mol KI = 0.271 mol KI 166.00 g KI M = mol L M = 0.271 mol 3.0 L M = 0.090 M MOLARITY How many moles of NaCl are in 1.5 L of a 3.0 M NaCl solution? What mass of salt is this? M = mol L 3.0 M = x mol 1.5 L 3.0 M(1.5 L) = x mol x = 4.5 mol MOLARITY 4.5 mol NaCl 58.44 g NaCl = 262.98 g NaCl 1 mol NaCl 260 g NaCl AGENDA 3/10/15 Check Molarity HW Warm-Up Notes on Dilution Salt Lab HW: Write-Up Lab WARM-UP Example: A 500.00 mL solution of HCl contains 45.0 grams of the chemical. What is the molarity of this solution? Ans: 2.47 M ANSWERS TO 1-5 ON SOLUTIONS PRACTICE 1. 2. 3. 4. 5. .901M 83.9 g KCl 6.09M 1.47 x 106 g KOH 20.5 M Pb in Sn DILUTIONS Dilutions – making a less concentrated solution from a stock solution soln of known concentration DILUTIONS M=mol/L → M x L = mol M1V1 = moles of solute before dilution M2V2 = moles of solute after dilution The moles of solute does not change during a dilution. You’re just adding more water. DILUTIONS M1V1 = M2V2 DILUTIONS Examples: How would you prepare 305 mL of 0.500 M AgCl from a 1.20 M stock solution? DILUTIONS M1 = 1.20 M V1 = ? M2 = 0.500 M V2 = 305 mL = 0.305 L M1V1 = M2V2 DILUTIONS (1.20M)(V1) = (0.500M)(0.305L) (1.20M)(V1) = 0.1525 1.20 1.20 V1 = 0.127 L V1 = 127 mL 127 mL of stock soln & 178 mL of H2O DILUTIONS To prepare 1.00 L of 6.0 M HCl, what volume of concentrated (12.1 M) HCl must be used? M1 = 12.1 M V1 = ? M2 = 6.0 M V2 = 1.00 L M1V1 = M2V2 DILUTIONS (12.1 M)(V1) = (6.0 M)(1.00 L) (12.1 M)(V1) = 6.0 12.1 12.1 V1 = 0.496 L V1 = 0.50 L V1 = 500 mL 500 mL of 12.1 M HCl should be added to 500 mL of H2O SALT SOLUTIONS LAB Safety: Bunsen Burners: Keep your hair tied back Tips: Have the fresh samples of water ready to go while boiling the first solution and salt solutions. Keep data on the back of the lab for easy reference. Be sure to use distilled water, not tap water. AGENDA 3/11/15 1st Hour: Complete Lab, graph and conclusion 7th and 8th: Review Findings in the lab Practice Dilution and Molarity calculations HW: Finish any make-up work you have left SALT LAB WARM-UP Answer these questions with your partner: 1. How did adding the salt to the water affect the boiling temperature of the water? 2. How did diluting the salt concentration affect the boiling temperature of the water? 3. Bonus question: Why would adding salt to pasta water make the pasta cook faster? CONCLUSION Take time to write up your lab conclusion. When you are complete turn in your lab and pick up the dilutions worksheet. When finished with the dilutions worksheet, pick up the molarity and dilution worksheet. AGENDA 3/12/15 1st Hour: Collect Lab Check Dilutions Hw Notes on Evaporation and Boiling Boiling Demonstration Colligative Properties HW: Complete WS as study guide for Quiz SALT LAB WARM-UP Answer these questions with your partner: 1. How did adding the salt to the water affect the boiling temperature of the water? 2. How did diluting the salt concentration affect the boiling temperature of the water? 3. Bonus question: Why would adding salt to pasta water make the pasta cook faster? PHASE CHANGE: EVAPORATION Evaporation – Process of changing from l g Occurs at any T Occurs at the surface of the liquid PHASE CHANGE: EVAPORATION Saturated air with vapor (“air is full”) PHASE CHANGE: EVAPORATION Vapor Pressure The pressure (collisions) caused by the vapor above a liquid in a sealed container of equilibrium Caused by the collision of vapor molecules with the surface of the liquid PHASE CHANGE: EVAPORATION VP depends on: T (as T ↑, evaporation ↑, vapor ↑ and VP ↑) Because more molecules have the E to break free of the surface T (as T ↓, evaporation ↓, vapor ↓ and VP ↓) Because fewer molecules have E to break free of the surface PHASE CHANGES: BOILING Occurs when the VP of a liquid = the atm P on it Vapor forming within the liquid, not at surface The pressure from the atmosphere would crush bubbles P inside = P outside PHASE CHANGE: BOILING Boiling Point – T at which VP = atmospheric P Normal Boiling Point (NBP) = BP when P = 1 atm P inside = P outside PHASE CHANGE: BOILING Why would the vapor pressure need to be equal to or greater than the atmospheric pressure? How could we increase the vapor pressure? 1 atm Think how to increase the amount of vapor present in a liquid. ANSWER: We heat it…vapor pressure is directly related to the temperature. .022 atm PHASE CHANGES What if you’re not at 1 atm? Pike’s Peak, CO CLC, IL PHASE CHANGES 1.05 atm (mine) 107oC 1.00 atm (IL) 100oC 0.894 atm (Denver) 94oC Pike’s Peak 89oC Mt. Everest 70oC H2O VP = 0.022 atm PHASE CHANGES Will foods cook faster in Denver? No, because the BP is lower, water is cooler, cooking takes longer. What causes the boiling point and melting point to change when a salt is dissolved in it? COLLIGATIVE PROPERTIES Properties that depend entirely on the number of particles dissolved in a given mass of solvent Ex: Boiling point and melting point COLLIGATIVE PROPERTIES Vapor Pressure Lowering Allows liquids to boil at temperatures lower than their normal boiling point. Vacuum Demo!! COLLIGATIVE PROPERTIES Why? = solvent = solute Because vaporization occurs at the surface and the solute is in the way….so less vaporizes, therefore VP is lower. *depends on the # of particles of solute COLLIGATIVE PROPERTIES 2. Boiling Point Elevation – a solution boils at a higher T than a pure solvent (like our salt lab) Why? Boiling occurs when VP = atm P Since VP is lowered by adding salt, more E must be added to raise VP to atm P Proportional to # of particles COLLIGATIVE PROPERTIES Example: Salt in H2O for cooking pasta H2O boils at a higher T, pasta cooks faster H2O does not boil faster COLLIGATIVE PROPERTIES 3. Freezing Point Depression – a solution freezes at a lower T than a pure solvent Why? Particles in liquid disrupt the orderly pattern of solid crystal, bonds cannot form as easily Must get colder to solidify Proportional to the # of particles COLLIGATIVE PROPERTIES Example: Melting Ice Sand doesn’t melt ice NaCl dissolves, melts ice by lowering fp AlCl3 better (more particles) AGENDA 3/13/15 Check Molarity and Dilutions HW Last minute questions before quiz Molarity and Dilutions Quiz AGENDA 3/16/15 Quizzes Tomorrow/Maybe Today Back to Balancing Equations Equations in Solutions Predicting States of matter *** GRAB A WS FROM THE BACK TABLE*** HW: Ionic Equations SOLUTIONS NaCl (s) H Na+ (aq) + - + - - + - + + - + - O H H H O H O O H H H O + H O H H H 3/10/2016 Free template from www.brainybetty.com 78 AGENDA 3/17/15 ST. PATTY’S DAY!! Review Quiz Ionic Equation Review HW Check Ionic Reaction Demo Energy/Phases Review HW: Energy and Ionic Equation Worksheet IONIC REACTIONS DEMO I have a solution of lead (II) nitrate and lithium chloride. Will a precipitate form? If not, why not? If yes, what is the precipitate that formed? Write a complete balanced reaction including phases. IONIC REACTION DEMO I have a solution of sodium hydroxide and a solution of hydrogen chloride. Will a precipitate form? If not, why not? If yes, what is the precipitate that formed? Write a complete balanced equation including phases. PHASE DIAGRAMS Describe the conditions of T and P where each phase is most likely to exist Gas Liquid High T, low P middle Solid Low T, high P 82 PHASE DIAGRAMS Phase Diagram – shows the relationship between the 3 phases in a sealed container 83 PHASE DIAGRAMS Features: Lines of Equilibrium 1. 2. 3. On the lines, the substance exists in equilibrium between two states At that T and P, both phases exist s s l g l g 84 PHASE DIAGRAMS Features: Triple Point One specific point at which all three phases exist in equilibrium in a sealed container A 85 PHASE DIAGRAMS Features: Critical Point Point past which neither liquid nor gas truly exist An intermediate fluid phase (plasma*) B 86 PHASE DIAGRAMS 87 Phase Diagram for H2O