Transcript Chemistry B11 Chapter 6 Solutions and Colloids Mixtures Mixture: is a combination of two or more pure substances. Homogeneous: uniform and throughout Air, Salt in.

Chemistry B11
Chapter 6
Solutions and Colloids
Mixtures
Mixture: is a combination of two or more pure substances.
Homogeneous: uniform and throughout
Air, Salt in water
Solution
Heterogeneous: nonuniform
Soup, Milk, Blood
Solutions
Gas in gas (air)
solid in solid (alloys)
Gas in liquid (cokes)
liquid in liquid (alcohol in water)
solid in liquid (sugar in water)
Solutions
Well-mixed (uniform) – single phase
homogenous
transparent
sugar in water
cannot be separated by filtration
cannot be separated on standing
Solutions (liquid in liquid)
Solvent: greater quantity (water)
for liquid in liquid
Solute: smaller quantity (sugar)
Immiscible: two liquids do not mix.
miscible: two liquids can mix.
(in any quantities)
alcohol in water
Solutions
Saturated: solvent contains or holds all the solute it can (at a given T).
maximum solute that solvent can hold (Equilibrium).
Unsaturated: solvent can hold more solute (at a given T).
Is not the maximum solute that solvent can hold.
Supersaturated: solvent holds more solute that it can normally hold
(at a given T).
(more than an equilibrium condition)
Temperature and Solutions
Solubility: the maximum solute that will dissolve in a given amount of a solvent
(at a given T).
T
Solubility 
T
Crystal is formed
Temperature and Solutions
T
Solubility 
Supersaturated solution
Seeding
A surface on which to
being crystallizing.
gas in liquid: T ↑
Solubility ↓
Global Warming
Pressure and Solutions
Henry’s law
P
Solubility  (gas in liquid)
Concentration
Concentration: amount of a solute dissolved in a given quantity of solvent.
1. Percent concentration:
Weight / volume (W / V)% =
Weight solute
Volume of solution (mL)
Weight / Weight (W / W)% =
Weight solute
× 100
Weight of solution
Volume / volume (V / V)% =
Volume solute (mL)
× 100
× 100
Volume of solution (mL)
Concentration
2. Molarity (M): number of moles solute dissolved in 1 L of solution.
Molarity (M) =
moles solute (n)
volume of solution (L)
Molarity × V = number of moles (n)
prepare the solution: M, V → n (mol) → m (g)
Prepare the solution
prepare the solution: M, V → n (mol) → m (g)
m (g)
Volumetric flask
Concentration
3. Parts per Million (ppm):
g solute
ppm =
× 106
g solvent
Parts per billion (ppb):
ppb =
g solute
× 109
g solvent
Dilution
Concentrated solution
(Stock solution)
Dilute solution
Dilution
M1V1 = moles(n)
before dilution
M2V2 = moles(n)
after dilution
M1V1 = M2V2
% V1 = % V2
Equivalent
Number of Equivalents (Eq) in 1 mole of each ion is number of
charges of that ion.
Ion
Charge
# of Equivalents in 1 mole
Na+
1+
1 Eq
Ca2+
2+
2 Eq
Fe3+
3+
3 Eq
Cl-
1-
1 Eq
SO42-
2-
2 Eq
Equivalent
Ex. 1: How many equivalents of CO32- are in 1 mole of Al2(CO3)3?
The charge of CO32- is 2- → 1 mole Al2(CO3)3 has 2 Eq CO32-.
Ex. 2: How many equivalents of Fe3+ are in 5 mole of Fe2O3?
The charge of Fe3+ is 3+ → 1 mole Fe2O3 has 3 Eq.
5 moles: 5 × 3 = 15 Eq
Water in our body
1. About 60% of our body.
2. Most of the reactions occur in aqueous solution.
3. Participates in many biochemical reactions.
4. Transports reactants and products from one place in our
body to another.
5. Eliminates the waste materials from cells and our body (urine).
Solvent and Solute
polar dissolves polar
like dissolves like
Nonpolar dissolves nonpolar
Ions Hydrated by H2O
Hydration
Solvent and Solute
All nitrates (NO3-) and acetate (CH3COO-) are soluble in water.
Most chlorides (Cl-) and sulfates (SO42-) are soluble in water.
(except AgCl, BaSO4, and …)
Most carbonates (CO32-), phosphates (PO43-) and
hydroxides (OH-) are insoluble in water.
(except NaOH, LiOH, KOH, and NH4OH)
Electrolytes
bulb
Electrolyte: conducts an electric current.
Na+
Clelectrolyte
+
-
Ionization (Dissociation)
NaCl → Na+ + Cl-
strong electrolytes: molecules dissociate completely into ions (NaCl).
weak electrolytes: molecules dissociate partially into ions (CH3COOH).
nonelectrolytes: molecules do not dissociate into ions (DI water).
Colloids
Solutions: diameter of the solute particles is under 1 nm.
Colloids: diameter of the solute particles is between 1 to 1000 nm.
non transparent, non uniform, large particles, cloudy (milky)
but a stable system
Colloids
Tyndall effect:
You can see the pathway of the light passes
through a colloid. (particles scatter light.)
emulsion: a mixture of immiscible substances (liquid-liquid).
(milk and mayonnaise)
Suspension
suspension: system does not stays stable and settle (> 1000 nm).
(sand in water)
Brownian motion
Random motion of colloid particles.
Dust
Why do colloidal particles remain in solution and do not stick together?
1. Surrounding water molecules prevent colloidal molecules
from touching and sticking together.
2. A charged colloidal particle encounters another particle
of the same charge, they repel each other.
Freezing and boiling point
bp 
If we dissolve a solute in a solvent:
ΔT = ikM
fp 
ΔT: change of bp or fp (T2 - T1)
i: number of particles
K: constant (depend on solute) – Kb Kf
M: molarity
NaCl  Na+ + Cl-
i=2
K2SO4  2K+ + SO42-
i=3
C2H6O2
i=1
Osmotic Pressure
Semipermeable
membrane
osmotic
pressure
Higher concentration → Higher osmotic pressure
Osmotic Pressure
Water flows from
low concentration
to
high concentration.
Osmotic Pressure
Osmolarity (osmol) = M × i
M: molarity
i: number of particles
Osmolarity ↑ → Osmotic pressure ↑
Isotonic solution
Hypotonic solution Hypertonic solution
Hemolysis
Crenation
The most typical isotonic solutions
0.9% (m/v) NaCl
5% (m/v) Glucose
0.9 g NaCl/100 mL of solution
5 g glucose/100 mL of solution
Higher than these numbers → Hypertonic solution
Lower than these numbers → Hypotonic solution
Dialysis
Dilute solution