Solutions

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Solutions

• Ch.13

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(13-1) Mixtures

• Suspension appears uniform, but separates out
  when settled
• Ex muddy water
• Colloid small particles suspended in a solvent
  doesnt settle out
• Ex milk

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Solution

• Solvent substance in which solute dissolves
• Solute substance dissolved
• Aqueous soln in which solvent is H2O

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Concentration

• Amt. of solute in a specific amt. of solvent or
  soln
• Low conc. dilute soln
• High conc. concentrated soln

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Measuring Conc.

• Molarity (M) mols of solute
• L of soln
• Molality (m) mols of solute
• kg solvent

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Molarity Practice

• Whats the molarity of a KCl soln that has a V of
  400 mL contains 85 g of KCl?
• List known
• V 400 mL
• m 85 g

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Molarity Practice

• Convert into appropriate units
• 400 mL x 1 L 0.4 L
• 1000 mL
• 85 g KCl x 1 mol 1.14 mol KCl
• 74.6 g
• Substitute solve
• M mols 1.14 mol 2.85 M
• L 0.4 L

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Molality Practice

• How many mols of NaF are required to make a 0.30
  m soln using 0.6 kg of water?
• List known
• m 0.30
• kg solvent 0.6

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Molality Practice

• 2. Write eq., substitute, solve
• m mols ? mols (m)(kg)
• kg (0.30 m)(0.6 kg)
• 0.18 mol

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Separating Mixtures

• Filtration
• Evaporation
• Centrifuge
• Distillation
• Drinking water from sea water
• Chromatography
• Separating dyes in ink

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(13-2) Solubility

• Max amt. of a chemical that will dissolve in a
  given quantity of solvent at a specified T
• Soluble can be dissolved
• Insoluble does not dissolve

Rxn of KI soln Pb(NO3)2 soln
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General Interest
Shellfish form their shells from CaCO3. The
organism secretes Ca2 from cells in contact w/
seawater, which contains dissolved CO2, some of
which is present as CO32-. The ions combine to
give a precipitate of CaCO3.
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General Interest
Kidney stones are generally also insoluble
calcium cmpds such as calcium carbonate, calcium
phosphate, or calcium oxalate.
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Henrys Law

• Solubility of a gas in a liquid is directly
  proportional to the partial P of that gas
• Pop bottle w/ CO2
• Gas solubility depends on P T
• Inc. P, inc. solubility
• Inc. T, dec. solubility

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Saturated

• Containing amt. of solute specified by solubility
• Supersaturated containing more than the amt. of
  solute specified by solubility

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Miscible

• Liquids that dissolve in 1 another
• Similar polarity
• Immiscible liquids that will not dissolve in
  each other
• Ex oil water

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(13-3) Conductivity

• Ability to conduct electric current
• Electrolyte conducts electricity
• Ex NaCl dissolved in H2O
• Ionic
• Nonelectrolyte does not conduct
• Ex C6H12O6 dissolved in H2O
• Covalent

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Electrolytes

• Strong electrolyte almost completely dissociates
  (separates into fragments) in soln
• Ex NaCl(s) H2O(l) ? Na(aq) Cl-(aq)
• Weak electrolyte small dissociates in soln
• Ex NH3(aq) H2O(l) ? NH4(aq) OH-(aq)

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Hydronium Ion

• H ion bonded to a H2O molecule (H3O)
• Hydration H2O molecules surround each ion in a
  soln

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(13-4) Colligative Properties

• Physical properties that are dependent on the
  of solute particles present rather than the
  particle identity

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Boiling-point Elevation

• Difference b/w the bp of a soln a pure
  substance
• Freezing-point depression difference b/w the fp
  of a pure solvent w/ a soln