Presentation on theme: "Properties of Solutions: Most things in life are solutions"— Presentation transcript:
1Properties of Solutions: Most things in life are solutions Properties of Solutions: Most things in life are solutions. Get with the program.Chapter 13
2February 13th, 2013Do Now:Clear desk except for a writing utensil- Intermolecular Forces Quiz
3Definitions GALORE Define the following words with a neighbor: Solvent:Solute:Aqueous solution:Entropy:Spontaneous:
4Ammonium Nitrate + Water Predict the resulting reaction for Ammonium Nitrate and WaterDo we expect this process to be endothermic or exothermic? Why?Why is this reaction surprising?What can we ask for the aim today?
5Natural AbilitiesHow is the ability of a substance to form a solution affected?Types of I.M.F in solution processNatural tendency of substances to mix/spread when not restrainedWhy is the mixing of gases a spontaneous process?No energy input from outside the systemWhy is it important to discuss entropy in solution?Increase in entropy is favored in solutionsExplain why NaCl mixes in water and not gasoline.
7…furthermore.Three types of intermolecular attraction in solution formation:Solute-solute: interactions between molecules of solute must be overcome to disperse soluteSolvent-solvent: interactions between solvent molecules must be overcome to make way for soluteSolvent-solute: occur as particles mixIn terms of intermolecular attraction, what must be true in order for a solution to form?In terms of intermolecular attractions, explain why heptane and pentane can mix.
8Water + NaClWrite a paragraph explaining why NaCl is able to dissolve in water. Include the following terms:Solvent-soluteSolute-soluteSolvent-solventIon-dipole attractionDefine:Solvation:Hydration:
9So what you’re saying is… As we experienced in our demo, solution processes generally are accompanied by:How might we be able to determine how the interactions in the solution influence enthalpy?Formulate an equation to calculate ∆Hsoln
10February 14th, 2013Do Now:Write a paragraph explaining why NaCl is able to dissolve in water. Include the following terms:Solvent-soluteSolute-soluteSolvent-solventIon-dipole attraction
11…Hess, you’ve come back!Predict for each of the three types of interactions whether or not they are endothermic or exothermic. Explain your reasoning.Why is enthalpy useful to us in determining extent of reaction?
16Is your brain saturated yet? How about super-saturated? On the molecular level, explain the interactions of solute and solvent as concentration increases.Define the following terms with a neighbor:Saturation:Unsaturated:Supersaturation:Solubility
17Explain the trend:How does solubility of gas relate to intermolecular forces?
19Mis-a-what? How do we differentiate between miscible and immiscible? How can we alter hexane to make is miscible? Explain in terms of attraction.
20Predict the trend:**Hint: how does the number of carbons affect solubility in water?
21February 15th, 2013DO NOW:Predict whether each of the following substances is more likely to dissolve in the solvent carbon tetrachloride or water:C7H16Na2SO4HClI2Arrange the following in order of increasing solubility in water (explain your reasoning *psst.. Please actually write the reason in your notebook.**):c5H11OH, c5H12, c5H11Cl, c5H10(OH)2
22Welp…As the world is evolving, the number of habitable lakes for wildlife is slowly declining.
23 Predict the trend between pressure and solubility. Can you think of an example?
24Explained.At equilibrium, rate of gas molecules entering and leaving solution is equal.Exert pressure: what happens to the rate at which molecules are colliding with the surface?How can we relate this to the partial pressure of gas?Solubility of gas in a liquid solvent increases in direct proportion to partial pressure of gas.
25Henry’s Law Relationship between pressure and gas solubility: Sg = kPg Sg= solubility of the gas in the solvent (usually expressed as molarity)Pg= partial pressure of the gas over solutionk= proportionality constant (Henry’s Law Constant)**k depends on solute, solvent, and temp.
26অনুশীলন (Bengali)Calculate the concentration of CO2 in a soft drink that is bottled with a partial pressure of 4.0 atm over the liquid at 25 degrees celcius. The Henry’s law constant for CO2 in water at this temperature is 3.4 x 10-2 mol/L-atm
27Temperature EffectsAs temperature increases, the solubility of most solid solutes increases. How do you think gas solubility is effected by temperature?
28Think about it…Why do bubbles form on the inside of the cooking pot when water is heated on a stove, even though the water temperature is well below the boiling point?
29Well how do we represent concentration? How can we differentiate between mass percentage, ppm, and ppb?When would we use ppm or ppb?IE: toxic concentrations expressed in ppm or ppb:Max allowable concentration of arsenic in drinking water is ppm. How do we express this in grams?
30Практика (Bulgarian)A solution is made by dissolving 13.5 g of glucose in kg of water. What is the mass percentage of solute in this solution?A 2.5 gram sample of groundwater was found to contain 5.4 microliters of zinc 2+. What is the concentration of Zn 2+ in ppm?
31February 20th, 2013Do Now:Calculate the mass percentage of NaCl in a solution containing 1.50 g of NaCl in 50.0 g of H2O.A commercial bleaching solution contains 3.62% by mass sodium hypochlorite (NaOCl). What is the mass of NaOCl in 2.50 kg of bleaching solution?
32What does this suggest for our aim? 3.0 Molar3.0 Molal
33Molarity, Molality, and Mole fractions: Oh My! How do we express mole fractions?IE: Solution contains 1.00 mol of HCl mol of H2O. What is the mole fraction of HCl?How do we express Molarity?IE: What is the molarity of a solution with 0.50 mol of solute in L solution?How do we express molality?IE: mols of NaOH is mixed with kg of H2O. What is the concentration?
34…huh? How can we differentiate between molality and molarity? **Note: when water is solvent, the 2 numbers will be very similar. Why?Why do we use molality when varying temperature of solution?
35Pràctica (Catalan)A solution is made by dissolving 4.35 g of glucose in 25 mL of 25 degrees celcius. Calculate the molality.What is the molality of a solution made by dissolving 36.5 g of Naphthalene (C10H5) in 425 g of Toluene (c7H8)?
36Converting UnitsSometimes it is necessary to interconvert units when given a different unit.IE: An aqueous solution of HCl contains 36% HCl by mass.
37Molal/Molar Conversions A solution with a denistry of g/mL contains 5.0 g of Toluene and 225 g of Benzene. Calculate the molarity.
39实践 (Chinese- simplified) Remember that worksheet you were given for homework? Time to go take another look at it…
40February 21st, 2013Do now:A solution containing equal masses of glycerol (C3H8O3) and water has a density of 1.10 g/ml. Calculate:The molality of glycerolThe mole fraction of glycerolThe molarity of glycerol
41So, why do properties of solutions change? Define Colligative Properties:Properties of solvents that depend on total concentration of solute particles presentGive Examples of Colligative Properties:Vapor-Pressure LoweringFreezing Point LoweringBoiling Point ElevationOsmotic Pressure
42Vapor-PressureRedefine the following words in terms of vapor pressure:Vapor Pressure:Volatile:Non-volatile:Describe what would happen if you added a nonvolatile solute to a volatile solvent.
44Raoult’s LawVapor pressure of solution containing non-volatile solue/volative solvent is proportional to solvent concentrationHow do we express this qualitatively?IE: Vapor pressure of 20 degrees Celsius is 17.5 torr. If temp is held constant and sugar is added, mol fraction of water is XH2O= How does the addition of glucose effect the vapor pressure?
45实践 (Chinese- Simplified) Glycerine- a nonvolatile nonelectrolyte with a density of 1.26 g/ml is used to make a solution with 50.0 mL glycerine with mL water. At 25 degrees Celsius, the vapor pressure of water is 23.8 torr and density is 1.00 g/ml.
46Una Mas.The vapor pressure of pure water at 110 degrees Celsius is 1070 torr. A solution of ethylene glycol and water has a vapor pressure of 1.00 atm at 110 degrees Celsius. What is the mole fraction of ethylene glycol?
47February 22, 2013Do Now:Calculate the Vapor Pressure of water above a solution prepared by adding 22.5 g of lactose (C12H22O11) to g of water at 338 K. (pure water = torr)Calculate the mass of propylene glycol (C3H8O2) that must be added to kg of water to reduce the vapor pressure by 2.88 torr at 40 degrees Celsius. (pure water = 55.3 torr)
48Ideal SolutionsUsing prior knowledge, how might we relate the concept of an ideal gas to that of an ideal solution?Explain what this means for solute-solute, solvent-solvent, and solute-solvent interactions.** Be aware, not all solutions are “ideal” will be discussed in later chapters.
49Boiling PointIf the addition of non-volatile solute lowers vapor pressure, how is the boiling point effected?
50Numerically speaking… How can we represent the increase in boiling point numerically?IE: NaCl is dissolved in water. A 1 molal solution is created. Calculate the boiling point elevation of the solution.Summarize: A solute dissolved in water causes the boiling point to increase by 0.51 degrees celsius. Does this necessarily mean that the concentration of the solute is 1.0 m? Explain.
52Freezing Point How do we determine the freezing point of a liquid? How is freezing point effected when creating solutions? Explain.
53Calculation time! How might we calculate the change in freezing point? IE: Automotive antifreeze consists of ethylene glycol, CH2(OH)CH2(OH), a nonvolatile nonelectrolyte. Calculate the boiling point and greezing point of a 25.0 mass % solution of ethylene glycol in water. (Kb= 0.51 C/m) (Kf= 1.86 C/m)
54February 28th, 2013Which of the following solutes will produce the largest increase in boiling point upon addition to 1 kg of water and whyCo(NO3)22 mol of KCl3 mol of ethylene glycol (C2H6O2)
55Osmosis Define semipermeable Define Osmosis Why does osmosis take place?*note: rate at which solvent passes from less concentrated solution (lower solute, higher solvent) to more concentrated solution is greater than the rate in the opposite direction
57Application Similar to ideal gas law: ∏ = (n/V)RT∏ = osmotic pressureV= volume of the solutionn= number of moles of soluteR = ideal gas constantT = temperature in KelvinHow can we change the equation to include Molarity?
58Behind door 1…Using these diagrams and the concept of osmotic pressure, label and define which of these are isotonic, hypotonic, and hypertonic.
59Cells? Why in Chemistry… Describe what would happen if a red blood cell was placed in a solution that is hypertonic relative to the intracellular solution.Crenation: process in which a cell shrivelsDescribe what would happen if the cell is hypotonic relative to intracellular fluids.Hemolysis: process of cell repture
60Praksa (Croatian)The average osmotic pressure of blood is degrees celsius. What molarity of glucose will be isotonic with blood?What is the osmotic pressure at 20 degrees Celsius of a M sucrose solution? (C12H22O11)
61Determination of Molar mass Any of the four colligative properties can be used to determine molar mass:1. Freezing Point Depression/ Boiling Point Elevation:A solution of unknown solute was prepared by dissolving g of the substance in 40.0 g of CCl4. The resultant boiling point of the solution was degrees higher than that of the pure solvent. Calculate the molar mass.
62Determination of Molar Mass Cont. Osmotic Pressure:The osmotic pressure of an aqueous solution of a certain protein was measured to determine the proteins molar mass. The solution contained 3.50 mg of protein dissolved in sufficient water to form 5.00 mL of solution. The osmotic pressure of the solution at 25 degrees celsius was found to be 1.54 torr. Calculate the molar mass.
63cvičit (czech)Camphor (C10H16O) melts at degrees Celsius and it has a large Kf= 40.0 C/m. When g of an organic substance of unknown molar mass is dissolved in g of liquid camphor, the freezing point is found to be What is the molar mass?A sample of 2.05 g of polystyrene of uniform polymer chain length was dissolved in enough toluene to form L of solution. The osmotic pressure of the solution was found to be 1.21 kPa at 25 degrees Celsius. Calculate the molar mass.