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Solutions

Solutions. Properties of Water Solutions. Predict the % water in the following foods. Predict the % water in the following foods. 88% water 94% water 85% water 86% water. Water in the Body. water gain water loss liquids 1000 mL urine 1500 mL

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Solutions

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  1. Solutions Properties of Water Solutions

  2. Predict the % water in the following foods

  3. Predict the % water in the following foods 88% water 94% water 85% water 86% water

  4. Water in the Body water gain water loss liquids 1000 mL urine 1500 mL food 1200 mL perspiring 300 mL cells 300 mL exhaling 600 mL feces 100 mL Calculate the total water gain and water loss Total ______ mL _____ mL

  5. Water • Most common solvent • A polar molecule O- a hydrogen bond H + H +

  6. Hydrogen Bonds Attract Polar Water Molecules

  7. Explore: Surface Tension HW • Fill a glass to the brim with water • How many pennies can you add to the glass without causing any water to run over? Predict _________________ Actual _________________ • Explain your results

  8. Explore 1. Place some water on a waxy surface. Why do drops form? 2. Carefully place a needle on the surface of water. Why does it float? What happens if you push it through the water surface? 3. Sprinkle pepper on water. What does it do? Add a drop of soap. What happens?

  9. Surface Tension • Water molecules within water hydrogen bond in all directions • Water molecules at surface cannot hydrogen bond above the surface, pulled inward • Water surface behaves like a thin, elastic membrane or “skin” • Surfactants (detergents) undo hydrogen bonding

  10. Solute and Solvent Solutions are homogeneous mixtures of two or more substances • Solute The substance in the lesser amount • Solvent The substance in the greater amount

  11. Nature of Solutes in Solutions • Spread evenly throughout the solution • Cannot be separated by filtration • Can be separated by evaporation • Not visible, solution appears transparent • May give a color to the solution

  12. Types of Solutions air O2 gas and N2 gas gas/gas soda CO2 gas in water gas/liquid seawater NaCl in water solid/liquid brass copper and zinc solid/solid

  13. Discussion Give examples of some solutions and explain why they are solutions.

  14. Learning Check SF1 (1) element (2) compound (3) solution A. water 1 2 3 B. sugar 1 2 3 C. salt water 1 2 3 D. air 1 2 3 E. tea 1 2 3

  15. Solution SF1 (1) element (2) compound (3) solution A. water 2 B. sugar 2 C. salt water 3 D. air 3 E. tea 3

  16. Learning Check SF2 Identify the solute and the solvent. A. brass: 20 g zinc + 50 g copper solute = 1) zinc 2) copper solvent = 1) zinc 2) copper B. 100 g H2O+5 g KCl solute = 1) KCl 2) H2O solvent = 1) KCl 2) H2O

  17. Solution SF2 A. brass: 20 g zinc + 50 g copper solute = 1) zinc solvent = 2) copper B. 100 g H2O+5 g KCl solute = 1) KCl solvent = 2) H2O

  18. Learning Check SF3 Identify the solute in each of the following solutions: A. 2 g sugar (1) + 100 mL water (2) B. 60.0 mL ethyl alcohol(1) and 30.0 mL of methyl alcohol (2) C. 55.0 mL water (1) and 1.50 g NaCl (2) D. Air: 200 mL O2(1) + 800 mL N2 (2)

  19. Solution SF3 Identify the solute in each of the following solutions: A. 2 g sugar (1) B. 30.0 mL of methyl alcohol (2) C. 1.5 g NaCl (2) D. 200 mL O2 (1)

  20. Like dissolves like A ____________ solvent such as water is needed to dissolve polar solutes such as sugar and ionic solutes such as NaCl. A ___________solvent such as hexane (C6H14) is needed to dissolve nonpolar solutes such as oil or grease.

  21. Learning Check SF4 Which of the following solutes will dissolve in water? Why? 1) Na2SO4 2) gasoline 3) I2 4) HCl

  22. Solution SF4 Which of the following solutes will dissolve in water? Why? 1) Na2SO4 Yes, polar (ionic) 2) gasoline No, nonnpolar 3) I2 No, nonpolar 4) HCl Yes, Polar

  23. Formation of a Solution H2O Hydration Na+ Cl- Na+ Dissolved solute Cl- H2O Na+ Cl- solute

  24. Electrolyte:a substance that conducts electricity when dissolved in water. Acids, bases and soluble ionic solutions are electrolytes. Non-electrolyte:a substance that does not conduct electricity when dissolved in water. Molecular compounds and insoluble ionic compounds are non-electrolytes. Electrolyte and Non-electrolyte

  25. Electrolytes • Some solutes can dissociate into ions. • Electric charge can be carried.

  26. Types of solutes high conductivity Strong Electrolyte - 100% dissociation, all ions in solution Na+ Cl-

  27. Types of solutes slight conductivity Weak Electrolyte - partial dissociation, molecules and ions in solution CH3COOH CH3COO- H+

  28. Types of solutes no conductivity Non-electrolyte - No dissociation, all molecules in solution Sugar C6H12O6

  29. Types of Electrolytes • Strong electrolyte dissociates completely. • Good electrical conduction. • Weak electrolyte partially dissociates. • Fair conductor of electricity. • Non-electrolyte does not dissociate. • Poor conductor of electricity.

  30. A weak electrolyte: CH3COOH(aq)← CH3COO-(aq) +H+(aq) → A non-electrolyte: CH3OH(aq) Representation of Electrolytes using Chemical Equations A strong electrolyte: MgCl2(s) → Mg2+(aq) + 2 Cl-(aq)

  31. Electrolytes in Action

  32. Strong Electrolytes Strong acids: HNO3, H2SO4, HCl, HClO4 Strong bases: MOH (M = Na, K, Cs, Rb etc) Salts: All salts dissolving in water are completely ionized. Stoichiometry & concentration relationship NaCl (s)  Na+ (aq) + Cl– (aq) Ca(OH)2 (s) Ca2+(aq) + 2 OH– (aq) AlCl3 (s)  Al3+ (aq) + 3 Cl– (aq) (NH4)2SO4 (s)  2 NH4+ (aq) + SO42– (aq)

  33. Writing An Equation for a Solution When NaCl(s) dissolves in water, the reaction can be written as H2O NaCl(s) Na+ (aq) + Cl- (aq) solid separation of ions in water

  34. Learning Check SF5 Solid LiCl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom(-) of water 2) hydrogen atom(+) of water B. The Cl- ions are attracted to the 1) oxygen atom(-) of water 2) hydrogen atom(+) of water

  35. Solution SF5 Solid LiCl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom(-) of water B. The Cl- ions are attracted to the 2) hydrogen atom(+) of water

  36. Rate of Solution You are making a chicken broth using a bouillon cube. What are some things you can do to make it dissolve faster? • Crush it • Use hot water (increase temperature) • Stir it

  37. How do I get sugar to dissolve faster in my iced tea? Stir, and stir, and stir Fresh solvent contact and interaction with solute Add sugar to warm tea then add ice Faster rate of dissolution at higher temperature Grind the sugar to a powder Greater surface area, more solute-solvent interaction

  38. Learning Check SF6 You need to dissolve some gelatin in water. Indicate the effect of each of the following on the rate at which the gelatin dissolves as (1) increase, (2) decrease, (3) no change A. ___Heating the water B. ___Using large pieces of gelatin C. ___Stirring the solution

  39. Learning Check SF6 You need to dissolve some gelatin in water. Indicate the effect of each of the following on the rate at which the gelatin dissolves as (1) increase, (2) decrease, (3) no change A. 1 Heating the water B. 2 Using large pieces of gelatin C. 2 Stirring the solution

  40. SolubilityPercent ConcentrationColloids and Suspensions

  41. Solubility The maximum amount of solute that can dissolve in a specific amount of solvent usually 100 g. g of solute 100 g water

  42. Saturated and Unsaturated • A saturated solution contains the maximum amount of solute that can dissolve. Undissolved solute remains. • An unsaturated solution does not contain all the solute that could dissolve

  43. UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form Solubility increasing concentration

  44. Factors Affecting Solid Solubility Polarity Temperature Surface Area Stirring

  45. Factors Affecting Solubility Polarity Temperature Pressure

  46. Intramolecular Bonding • Intramolecular bonding refers to the chemical bonding that holds atoms together within a molecule of a compound Covalent bonding and ionic bonding are the two main types of intramolecular bonding • Covalent bonding involves the sharing of valence electrons involves the sharing of valence electrons between two atoms. POLAR- unequal sharing of electrons NON POLAR – equal sharing of electrons • Ionic bonding involves the transference of valence electrons

  47. Learning Check S1 At 40C, the solubility of KBr is 80 g/100 g H2O. Indicate if the following solutions are (1) saturated or (2) unsaturated A. ___60 g KBr in 100 g of water at 40C B. ___200 g KBr in 200 g of water at 40C C. ___25 KBr in 50 g of water at 40C

  48. Solution S1 At 40C, the solubility of KBr is 80 g/100 g H2O. Indicate if the following solutions are (1) saturated or (2) unsaturated A. 2 Less than 80 g/100 g H2O B. 1 Same as 100 g KBr in 100 g of water at 40C, which is greater than its solubility C. 2 Same as 60 g KBr in 100 g of water, which is less than its solubility

  49. Temperature and Solubility of Solids Temperature Solubility (g/100 g H2O) KCl(s) NaNO3(s) 0° 27.6 74 20°C 34.0 88 50°C 42.6 114 100°C 57.6 182 The solubility of most solids (decreases or increases ) with an increase in the temperature.

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