Solutions

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Solutions their Physical Properties
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Solutions Solutions Solutions
Homogeneous mixtures are called solutions. Homogeneous mixtures are called solutions.
Solvent Solvent solute
is the component present in greatest amount or determines the state of solution exist is the component present in greatest amount or determines the state of solution exist is a component present in a lesser quantity and it is said to be dissolved in the solvent.
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Solute Solvent Solution example
Gas Gas Gas Air
Gas Liquid Liquid soda (CO2 in H2O)
Liquid Liquid Liquid ethanol in water
Solid Liquid Liquid Saline solution (NaCl in H2O)
Gas Solid Solid H2 in Pd
Solid Solid Solid 14 karat gold (Ag in Au)
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Solution Concentrations

• Mass of solute
• Percent by mass ------------------------
  x 100
• Mass of
  solution
• Volume of solute
• Percent by volume ------------------------- x
  100
• Volume of
  solution
• Mass of solute
• Mass / volume percent --------------------- x
  100 (gr/100ml)
• Volume of
  solution

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Solution Concentrations

• Number of moles of solute
• Molarity ------------------------------------
  -----------
• Number of liters of
  solution
• Number of moles of solute
• Molality -------------------------------------
  -------------
• Number of kilograms of
  solvent
• Moles of component i
• Mole fraction --------------------------------
  -------------------------
• total moles of all
  solution components
• Parts per million (ppm),
  Parts Per Billion(ppb)
• mg solute ?g
  solute
• 1 ppm --------------------
  1 ppb -----------------------
• kg solution
  kg solution

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• question.
• A solution has a density of 1.235g/ml and
  contains 90.0 glycerol C3H8O3 and 10 H2O by
  mass. Determine
• a- the molarity of C3H8O3
• b- the molarity of H2O
• c- mole fraction of C3H8O3
• d- mole percent of H2O
• e- the molality of H2O

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Solubility is the maximum amount of solute that dissolves in a given quantity of solvent at a specific temperature to produce a saturated solution

saturated solution. The solution in which no more solute can be dissolved is said to be saturated solution.

Super saturated solution. is a solution in which has higher amount of solute than saturated solution
Unsaturated solution is a solution in which contain less amount of solute than saturated solution
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• Solubility of most of solids increase with
  temperature.
• Solubility of gases decrease with increased
  temperature
• Solubility of a gas increases as the gas pressure
  is increased.
• Types of solvent and solute is important,
• like dissolves like, generally nonpolar
  substances are soluble in nonpolar substances,
  polar solvents dissolves ionic and polar
  substances.

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• Solution Process
• a- Separation of solvent molecules from one
  another
• Pure solvent ? separated solvent molecules
  ? H gt 0
• b- Separation of solute molecules from one
  another
• Pure solute ? separated solute molecules
  ? H gt 0
• c- mixing solvent solute molecules
• separated solvent molecules
• 
  ? solution ? H lt 0
• separated solute molecules

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ideal solution
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? H solution ? H a ? H b ? Hc
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• Intermolecular Forces in Mixtures
• Like dissolves like
• Substances with similar intermolecular attractive
  forces tend to be soluble in one another.
• Polar liquids tend to dissolve in polar solvents.
• Hydrogen bonding interaction between solute and
  solvent may lead to high solubility. (In alcohols
  as the length of the carbon chain increase, the
  solubility of alcohols in water decreases)
• The solubility of ionic compounds in water varies
  from one solid to another. (strength of bonding
  forces within the solid)
• - Nonpolar substances are soluble in nonpolar
  substances.

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• Question predict whether each of the following
  subtances is more likely to dissolve in CCl4 or
  in H2O
• C7H16 NaHCO3 HCl I2

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Solubility Temperature

• Solubility of most of solids increase with
  temperature.
• Solubility of gases decrease with increased
  temperature

crystallization
saturated solution. The solution in which no more solute can be dissolved is said to be saturated solution.
Super saturated solution. is a solution in which has higher amount of solute than saturated solution
Unsaturated solution is a solution in which contain less amount of solute than saturated solution
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• A solution is prepared by dissolving 95g NH4Cl in
  200.0g H2O at 60C,
• What mass of NH4Cl will crystallize when the
  solution is cooled to 20 C?
• The solubility of NH4Cl
• At 20 C is 37gNH4Cl/100gH2O
• At 60 C is 56gNH4Cl/100gH2O

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Solubility Pressure

• Solubility of a gas increases with increasing
  pressure

Henrys Law
C k Pgas
C solubility of gas k
Henrys Law constant Pgas is the partial
pressure of gas above the solution
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The solubility of pure nitrogen in blood at body
temperature (37C) and 1 atm is 6.2x10-4M. If a
diver breathes air (XN2 0.78) at a depth where
the total pressure is 2.5atm, calculate the
concentration of nitrogen in his blood?
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Vapor Pressures of Solutions

• Roault, 1880s.
• Dissolved solute lowers vapor pressure of
  solvent.
• The partial pressure exerted by solvent vapor
  above an ideal solution is the product of the
  mole fraction of solvent in the solution and the
  vapor pressure of the pure solvent at a given
  temperature.
• PA ?A P
• ?A Mole fraction
• P vapor pressure of pure solvent

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• Calculate the vapor pressure lowering caused by
  the addition of 100g sucrose (C12H22O11) to 1000g
  of water. (water pressure of pure water at 25C
  is 23.8mmHg.

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• A solution contains 102g of sugar
  (Mw342.30g/mol) in 375g of water. Calculate the
  vapor pressure lowering at 25C (vp of pure water
  23.76mmHg at 25C )

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• The vapor pressures of pure benzene and pure
  toluen at 25C are 95.1 and 28.4mmHg
  respectively,when 1 mol benzene mixed with 1 mol
  toluen calculate the total vapor presure of the
  solution.

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When a solution and a pure solvent (or two
solution of different concentration) are
separated by a semipermeable membrane, solvent
molecules pass through the membrane in a process
called osmosis.
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The osmotic pressure is equal to the external
pressure to prevent osmosis
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Osmotic Pressure
When a solution and a pure solvent (or two
solution of different concentration) are
separated by a semipermeable membrane, solvent
molecules pass through the membrane in a process
called osmosis. The osmotic pressure is equal
to the external pressure to prevent osmosis
pV nRT
M RT
For dilute solutions of electrolytes
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Reverse Osmosis - Desalination
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• The average osmotic pressure of blood is 7.7atm
  at 25C. What concentration of glucose will be
  isotonic with blood.
• Isotonic solutions are the solutions which have
  same osmotic pressure.

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Freezing-Point Depression and Boiling Point
Elevation
?Tb -Kb i m
?Tf -Kf i m
m molality i vant Hoff
factor
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vant Hoff
measured ?Tf
0.0361C
i 1.98
expected ?Tf
0.0186C
p -i M RT
?Tf -i Kf m
?Tb -i Kb m
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• List the following solutions in order to their
  expected freezing points
• 0.050m CaCl2
• 0.150m NaCl
• 0.100m HCl
• 0.050m HC2H3O2 (acetic acid)
• 0.100m C12H22O11

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• Calculate the freezing point and the boiling
  point of a solution of 100.0g ethyleneglicol
  (C2H6O2) in 900.0g H2O
• For water Kb0.52C/m Kf 1.86 C/m

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• The osmotic pressure of 5g/L hemoglobin solution
  at 25C is 0.0018atm, calculate the Mw of
  hemoglobin

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• When 0.2 of a nonionic subtances dissolved in 50g
  puer water the freezing point of this solution is
  found -0.22 C, calculate the Mw of the subtances

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• To determine the molar mass of vasopressin,
  10.00g of vasopressin is dissolved in 50.00g of
  Naphthalene (kf6.94C/m) the freezing point of
  the mixture is determined to be 79.01C, that of
  pure Naphthalene is 80.29C. what is the molar
  mass of vasopressin?

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Naphthalene (Mw128.2g/mol) is the active
ingredient of moth balls. in a solution prepared
by mixing 25.0g Naphthalene with 0.750L of CS2
(d1.263g/ml). Assume that volume remains 0.750L
when the solution is prepared.

• what is the mass percent of Naphthalene in the
  solution
• what is the concentration of Naphthalene in ppm
• what is the density of the solution
• what is the molarity of Naphthalene in the
  solution
• what is the molality of Naphthalene in the
  solution
• the vapor pressure of pure CS2 at 25C is
  358mmHg. Assume that the vapor pressure exerted
  by Naphthalene at 25C is negligible. What is the
  vapor pressure of the solution at this
  temperature?
• What is the osmotic pressure of the solution
• The normal boiling point of CS2 is 46.13C (Kb
  2.34C/m) what is the normal boiling point of the
  solution?