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Solution Chemistry. Recall that a Solution:. Is a homogeneous mixture that forms when one substance disperses uniformly throughout another. Recall that a Solution:. may be any phase: Solid solids evenly spread throughout Liquid liquid solvent with gas, solid, or liquid dissolved in it
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Recall that a Solution: • Is a homogeneous mixture that forms when one substance disperses uniformly throughout another.
Recall that a Solution: • may be any phase: Solid solids evenly spread throughout Liquid liquid solvent with gas, solid, or liquid dissolved in it Gas gases or vapors dissolved in one another
Recall that a Solution: • Does not settle on standing and will pass directly through a filter
Physical vs. Chemical Solutions • Physical solutions are the result of physical changes, and therefore can be separated physically. • Chemical solutions are the result of chemical reactions, and therefore cannot be separated by physical separation.
Solution Composition • Solute: Substance being dissolved, may be solid, liquid, or gas • Solvent: The dissolving medium, will be present in greater quantity. If the solvent is water aqueous If the solvent is alcohol tincture
Practice • For each of the following solutions, determine the solute and the solvent. • 20.0g of H2O & 35.0g of alcohol • 15.5g of alcohol & 2.5g of I2 • 0.002g of O2 & 200.5g of H2O
Solvation or Hydration NaCl(s) + H2O Na+(aq) + Cl-(aq)
Ionic Compounds in Water • Ionic compounds dissociate in water so that each ion separates from the solid structure and disperses throughout the solution.
Electrolytes • A substance whose aqueous solution contains ions, and therefore can conduct electricity
Molecules in Water • Molecules can dissolve in water if there are complementary intermolecular forces; however, the molecules remain intact rather than dissociating into ions.
Nonelectrolytes • A substance that does not form ions in a solution.
Solubility • The amount of substance that can be dissolved in a given quantity of solvent at a specific temperature
Solution Equilibrium • Solute + Solvent dissolve Solution • Solute + Solvent crystallize Solution Solute + Solvent Solution
Saturation • Which one is saturated? • Regardless of saturation, all solutions will be clear and homogeneous!
Saturation • Saturated Solutions: Have the maximum amount of solute dissolved in them. No more solute can dissolve. Will be at equilibrium with undissolved solute. • Unsaturated Solutions: Have less than the maximum amount of solute dissolve in them. • Supersaturated Solutions: Have more than the maximum amount of solute dissolved in them This is not normally possible. If a crystal is added to a supersaturated solution, precipitation of all the extra solute will occur.
Factors Affecting Solubility Solute-Solvent Interactions Soluble Insoluble Insoluble Soluble Insoluble Soluble
Alcohol Solubility Alcohol: hydroxyl group on a carbon chain Alcohol solubility *The greater the number of OH groups, the more water soluble. *The longer the carbon chain, the more organic-solvent soluble.
Gas Solubility • Kr (84 amu), N2(28 amu), CO (28 amu), O2 (32 amu), Ar (40 amu) From slide 139, Unit 5 PPT: • When the molecules of two substances have comparable molecular weights and shapes, dispersion forces will be approximately equal. In this case, the more polar molecules will have the greater attractive forces. • When the molecules of two substances differ widely in molecular weights, dispersion forces tend to be decisive in determining which substance has the stronger intermolecular attractions. In this case, The larger the molecule, the greater the attractive forces. • N2, CO, O2, Ar, Kr
Factors Affecting Solubility Pressure