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Solutions, Suspensions Colloids

Solutions, Suspensions Colloids. Solutions . Appears to be a single substance but really two or more substances dissolved in a solvent and evenly distributed Very small particles that never settle out Homogeneous. Examples of Solutions .

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Solutions, Suspensions Colloids

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  1. Solutions, Suspensions Colloids

  2. Solutions • Appears to be a single substance but really two or more substances dissolved in a solvent and evenly distributed • Very small particles that never settle out • Homogeneous

  3. Examples of Solutions • Alloys – solid solutions of metals or non-metals dissolved in metals • Iced tea, salt water, soda, gasoline

  4. Solute versus Solvent • A solute is the substance in a solution that gets dissolved • A solvent is the substance in a solution that does the dissolving • If something is soluble, the solute can be dissolved in a particular solvent • If something is insoluble, the solute will not be dissolved in a particular solvent • Solutes can be soluble in some solvents but insoluble in others

  5. Concentration • The comparison of solute to solvent • When there is not a lot of solute compared to solvent, the solution is dilute • When there is a lot of solute compared to solvent, the solution is concentrated

  6. Saturated Solutions • Saturated solution – contains all of the solute it can hold at a given temperature. • If you add even one more molecule of the solute, it will fall out of solution and rest on the bottom

  7. Unsaturated Solutions • Contains less solute than it can hold at a given temperature • Can add more solute and it wont fall out of the solution

  8. Supersaturated Solution • Solution that holds more than it usually would at a given temperature

  9. Solubility • The amount of solute needed to make a saturated solution in a given solvent at a given temperature • For solid solute in liquid solvent – solubility rises as temperature rises. • For gas solute in a liquid solvent – solubility lowers as temperature rises ex – soda goes flat at warm temperatures

  10. Solubility Table gases solids Solubility vs. Temperature for Solids 140 KI 130 120 NaNO3 110 100 KNO3 90 80 HCl NH4Cl 70 Solubility (grams of solute/100 g H2O) 60 NH3 KCl 50 40 30 NaCl KClO3 20 10 SO2 LeMayJr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517 images.hboys2011.multiply.multiplycontent.com/.../SOLUBILITY%20CURVE%202.ppt?... 0 10 20 30 40 50 60 70 80 90 100

  11. How to determine the solubility of a given substance? • Find out the mass of solute needed to make a saturated solution in 100 cm3 of water for a specific temperature(referred to as the solubility). • This is repeated for each of the temperatures from 0ºC to 100ºC. The data is then plotted on a temperature/solubility graph,and the points are connected. These connected points are called a solubility curve.

  12. How to use a solubility graph? A. IDENTIFYING A SUBSTANCE ( given the solubility in g/100 cm3 of water and the temperature) • Look for the intersection of the solubility and temperature.

  13. Example: What substance has a solubility of 90 g/100 cm3 of water at a temperature of 25ºC ?

  14. Example: What substance has a solubility of 200 g/100 cm3 of water at a temperature of 90ºC ?

  15. Look for the temperature or solubility • Locate the solubility curve needed and see for a given temperature, which solubility it lines up with and visa versa.

  16. What is the solubility of potassium nitrate at 80ºC ?

  17. At what temperature will sodium nitrate have a solubility of 95 g/100 cm3 ?

  18. At what temperature will potassium iodide have a solubility of 230 g/100 cm3 ?

  19. What is the solubility of sodium chloride at 25ºC in 150 cm3 of water ? • From the solubility graph we see that sodium chlorides solubility is 36 g.

  20. C. Determine if a solution is saturated,unsaturated,orsupersaturated. • If the solubility for a given substance places it anywhere on it's solubility curve it is saturated. • If it lies above the solubility curve, then it's supersaturated, • If it lies below the solubility curve it's an unsaturated solution. Remember though, if the volume of water isn't 100 cm3 to use a proportion first as shown above.

  21. Sol. Sol. To To Solids dissolved in liquids Gases dissolved in liquids As To , solubility As To , solubility

  22. Sometimes you'll need to determine how much additional solute needs to be added to a unsaturated solution in order to make it saturated. For example,30 grams of potassium nitrate has been added to 100 cm3 of water at a temperature of 50ºC.

  23. How many additional grams of solute must be added in order to make it saturated? From the graph you can see that the solubility for potassium nitrate at 50ºC is 84 grams

  24. If there are already 30 grams of solute in the solution, all you need to get to 84 grams is 54 more grams ( 84g-30g )

  25. gases solids Solubility vs. Temperature for Solids 140 KI Classify as unsaturated, saturated, or supersaturated. 130 120 NaNO3 110 80 g NaNO3 @ 30oC 45 g KCl @ 60oC 50 g NH3 @ 10oC 70 g NH4Cl @ 70oC 100 KNO3 90 =unsaturated 80 per 100 g H2O HCl NH4Cl 70 Solubility (grams of solute/100 g H2O) =saturated 60 NH3 KCl 50 =unsaturated 40 30 NaCl KClO3 20 =supersaturated 10 SO2 LeMayJr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517 images.hboys2011.multiply.multiplycontent.com/.../SOLUBILITY%20CURVE%202.ppt?... 0 10 20 30 40 50 60 70 80 90 100

  26. Methods to speed up dissolving • Crushing a solute increases the surface area of the solute allowing more solvent to surround it thus dissolving it faster • Ex. Putting butter in macaroni and cheese • Heating a solution increases the energy of the molecules making them move more quickly thus spreading the solute throughout the solvent and speeding up the rate at which the solute dissolves • Ex- cooking iced tea • Mixing has the same effect as heating does • Ex- making chocolate milk

  27. Suspensions • A suspension is a mixture in which particles of material are dispersed throughout a liquid or gas and are large enough to settle out • The particles are insoluble • Heterogeneous mixtures • Ex snow globe

  28. Colloids • Have properties of both solutions and suspensions • Particles in a colloid are much smaller than particles in a suspension • Colloids have the same definition as suspensions in that a colloid is a mixture in which particles of material are dispersed throughout a liquid or gas, but the particles of a colloid are not large enough to settle out • Particles in a colloid scatter light • Ex milk, fog, jello

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