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Solutions

Solutions. What is a solution ?. A homogeneous mixture Composed of a solute dissolved in a solvent. Solute. Solvent. How is a solution formed?. Through the process of Solute particles separate from each other and mix with the solvent particles Solvent particles

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Solutions

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  1. Solutions

  2. What is a solution? A homogeneous mixture Composed of a solute dissolved in a solvent Solute Solvent

  3. How is a solution formed? Through the process of Solute particles separate from each other and mix with the solvent particles Solvent particles surround the solute particles and pull them away from other solute particles solvation

  4. Solute and Solvent Solvent Does the dissolving Greater quantity (usually) Solute What is dissolved Lesser quantity (usually)

  5. Like dissolves like Baking soda will dissolve in water, but not in oil…..why? “Like dissolves like” refers to the bonding and polarity of the particles in the solute and solvent Polar means a substance has a positive and a negative end Ionic compounds

  6. Ionic compounds in solution Cl- Cl- Cl- Cl- Na+ Na+ Na+

  7. Solubility Only a certain amount of solute can dissolve in a solvent under a certain set of conditions When too much solute is added to a solution at that temperature, the excess solute will crystallize and fall out of solution Solubility is the maximum amount of a solute that dissolves in a solvent at a given temperature

  8. Saturation A saturated solution contains the maximum amount of dissolved solute for a given amount of solvent at a specifictemperature and pressure

  9. Supersaturation A supersaturated solution contains more dissolved solute than a saturated solution at the same temperature.

  10. Solubility Curves Shows how much solute will dissolve in 100 g of water at a certain temperature The line represents the saturated amount of solute Underneath the line represents an unsaturated amount Above the line represents a supersaturated amount

  11. NaNO3 • Which substance is most soluble at 40°C? ~ 50 grams • How many grams of NH4Cl will dissolve at 50°C? Yb2(SO4)3 KNO3 • What two substances have the same solubility at 24°C? • If you place 70 grams of KBr into 100g of water at 60°C, what unsaturated type of solution have you made? • How many grams of NaNO3 will dissolve in 300.0g of water at ~ 240 grams (80 x 3) 10.0°C?

  12. Increasing Solubility - Solids Increase the temperature Why? Increases the amount of solute-solvent collisions and increases speed and energy of particles Agitate the solution (stir) Why? Brings more solvent particles closer to the solute Decrease the particle size Increases the surface area of the solute, making it easier for solvent particles to surround the solute

  13. Increasing Solubility – Gases Decrease the temperature Increase the pressure If you increase the pressure, think of pressing the gas particles into the liquid. Increasing pressure always increases the amount of gas that can be dissolved in a liquid.

  14. Rate of Solvation Greater solubility = Faster solvation The same factors that increase solubility, increase the rate of solvation

  15. Concentration The larger the ratio of solute to solvent becomes, the more concentrated the solution is. Concentrated – large ratio of solute to solvent Dilute – small ratio of solute to solvent

  16. Rates of Reaction Concentration affects the rate of reaction Concentrated solutions react faster than dilute solutions

  17. Molarity Most commonly used in chemistry Abbreviated as M Moles of solute in per liter of solution moles of solute Liters of solution M =

  18. Electrolytes Electrolyte – ionic compound whose aqueous solution conducts an electric current – electrolyte – non-electrolyte NaCl Sugar How many moles of ions are produced by dissolving 1 mole of NaCl in water?

  19. Colligative Properties Colligative - depending on the collection Properties dependent on concentration, number of particles present

  20. Boiling Point Elevation When vapor pressure equals atmospheric pressure, water boils More particles = lower vapor pressure Lower vapor pressure = higher boiling point More particles = higher boiling point Which raises boiling point more, 1 mole of NaCl in water, or 1 mole of sugar in water?

  21. Freezing Point Depression Solute particles interfere with attraction between solvent particles More particles = lower freezing point

  22. Osmosis Osmosis – diffusion of solvent across a semi-permeable barrier Solvent goes from: Area of more solvent → Area of less solvent

  23. Osmosis Semi-permeable barrier Pure Solvent Solution

  24. Osmosis and Concentration Higher concentration = more osmotic pressure

  25. Osmosis and you

  26. Colligative Properties Review Atmosphere Vapor Pressure

  27. Miscible and Immiscible • Substances that are miscible will dissolve in each other. • Example: alchohol and water • Substances that are immiscible will mix but immediately separate. • Example: oil and vinegar

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