1. Definitions Solution - homogeneous mixture
Solute - substance being dissolved
Solvent - present in greater amount

2. Solutions What the solute and the solvent are determines
whether a substance will dissolve.
how much will dissolve.
A substance dissolves faster if it is stirred or
shaken.
The particles are made smaller.
The temperature is increased.
Why?
Stirring
In order to dissolve the solvent molecules must touch the solute.
Solvent molecules hold on to and surround the solute
Stirring moves fresh solvent next to the solute.
Dissolves faster
Particle Size
The solvent touches the surface of the solute.
Smaller pieces increase the amount of surface of the solute.
Solvent and solute touch each other more often
Smaller particles dissolve faster
Temperature
Higher temperature makes the molecules of the solvent move around faster and contact the solute harder and more often.
More pieces are broken off
Speeds up dissolving.
Usually increases the amount of solid that will dissolve.

3. Solution = Solute + Solvent
Solute - gets dissolved
Solvent - does the dissolving
Aqueous (water)
Tincture (alcohol)
Amalgam (mercury)
Organic
Polar
Non-polar
Dental filling
Solutions are always homogeneous – evenly mixed.
Solutions
– In all solutions, whether gaseous, liquid, or solid, the substance present in the greatest amount is the solvent, and the substance or substances present in lesser amounts are the solute(s).
– Solute does not have to be in the same physical state as the solvent but the physical state of the solvent determines the state of the solution.
– If solute and solvent combine to give a homogeneous solution, solute is said to be soluble in the solvent.
The difference between hydrophilic and hydrophobic substances has substantial consequences in biological systems.
– Vitamins can be classified as either fat soluble or water soluble.
1. Fat-soluble vitamins (Vitamin A) are nonpolar, hydrophobic molecules and tend to be absorbed into fatty tissues and stored there.
2. Water-soluble vitamins (Vitamin C) are polar, hydrophilic molecules that circulate in the blood and intracellular fluids and are excreted from the body and must be replenished in the daily diet.
Nightmare on White Street
Chem Matters, December 1996

4. Solution Definitions solution: a homogeneous mixture
-- evenly mixed at the particle level
-- e.g., salt water
alloy:
a solid solution of metals
-- e.g., bronze = Cu + Sn; brass = Cu + Zn
solvent: the substance that dissolves the solute
water
salt
Solutions
– A homogeneous mixture in which substances present in lesser amounts, called solutes, are dispersed uniformly throughout the substance in the greater amount, the solvent
– Aqueous solution — a solution in which the solvent is water
– Nonaqueous solution — any substance other than water is the solvent
– Water is essential for life and makes up about 70% of the mass of the human body.
– Many of the chemical reactions that are essential for life depend on the interaction of water molecules with dissolved compounds.
soluble:
“will dissolve in”
miscible:
refers to two gases or two liquids that form
a solution; more specific than “soluble”
-- e.g., food coloring and water

5. Types of Solutions Solute Solvent Solution Gaseous Solutions
liquid
air (nitrogen, oxygen, argon gases)
humid air (water vapor in air)
Liquid Solutions
solid
carbonated drinks (CO2 in water)
vinegar (CH3COOH in water)
salt water (NaCl in water)
Solid Solutions
dental amalgam (Hg in Ag)
sterling silver (Cu in Ag)
Solutions are not limited to gases and liquids; solid solutions also exist.
• Amalgams, which are usually solids, are solutions of metals in liquid mercury.
• Network solids are insoluble in all solvents with which they do not react chemically; covalent bonds that hold the network together are too strong to be broken and are much stronger than any combination of intermolecular interactions that might occur in solution.
• Most metals are insoluble in all solvents but do react with solutions such as aqueous acid or base to produce a solution; in these cases the metal undergoes a chemical transformation that cannot be reversed by removing the solvent.
Charles H.Corwin, Introductory Chemistry 2005, page 369

6. Factors Affecting the Rate of Dissolution
As To , rate
1. temperature
As size , rate
2. particle size
More mixing, rate
Formation of a solution from a solute and a solvent is a physical process, not a chemical one.
Both solute and solvent can be recovered in chemically unchanged form using appropriate separation methods.
Dissolution of a solute in a solvent to form a solution does not involve a chemical transformation.
Substances that form a single homogeneous phase in all proportions are said to be completely miscible in one another.
If two substances are essentially insoluble in each other, they are immiscible.
3. mixing
4. nature of solvent or solute

7. Classes of Solutions aqueous solution: solvent = water
water = “the universal solvent”
amalgam:
solvent = Hg
e.g., dental amalgam
tincture:
solvent = alcohol
e.g., tincture of iodine (for cuts)
organic solution:
solvent contains carbon
e.g., gasoline, benzene, toluene, hexane

8. Non-Solution Definitions
insoluble:
“will NOT dissolve in”
e.g., sand and water
immiscible:
refers to two gases or two liquids that will NOT form a solution
e.g., water and oil
suspension:
appears uniform while being stirred, but settles over time

9. Solubility Experiment 1: Add 1 drop of red food coloring A B A B
Before
Water
HOT
AFTER
COLD
A B
Miscible – “mixable”
two gases or two liquids
that mix evenly
Water
COLD
Water
HOT
You should observe that temperature effects the rate of solution. As the temperature of the liquid solvent increases, the molecules move faster, and the food coloring dissolves more quickly.
A B

10. Solubility Experiment 2: Add oil to water and shake T0 sec T30 sec
AFTER
Before
Immiscible – “does not mix”
two liquids or two gases
that DO NOT MIX
Oil
You should observe that for solutions to mix they must be chemically similar. Polar and polar molecules will mix, non-polar and non-polar molecules will mix, but polar and non-polar molecules will not mix. The reasons for this will be explained later.
Remember, ‘like dissolves like’. polar dissolves polar
non-polar dissolves non-polar
Water
Water
T0 sec
T30 sec

11. Muddy Water: Dissolved Solids
Experiment 3:
Add soil to water, shake well, and allow to settle
AFTER
Before
Muddy
Water
Dissolved solids can be calculated
as a percentage:
v/v (volume/volume)
w/v (weight/volume)
w/w (weight/weight)
Water
5% v/v soil in water
5 mL solid / 95 mL water
T1 min T5 min
5 mL / 100 mL = 5%

12. Muddy Water: Flocculation
Al2(SO4) Ca(OH)2  2 Al(OH) CaSO4
Experiment 4:
Add soil to water, shake well, and allow to settle
AFTER
AFTER
Before
Before
Muddy
Water
Muddy
Water
Water
Water
Demonstrate flocculation – a method used to settle out solids from waste water.
Two 50-mL graduated cylinders
pea-sized ball of moist mud (clay or silty-clay) in each
Fill ¾ full of tap water
Cover top with thumb and shake until well-mixed
Go on with something else for minutes (like stoichiometry calculations dealing with Al2(SO4) Ca(OH)2  2 Al(OH) CaSO4
ADD POWDERED MIXTURE OF ~3 g Al2(SO4) H2O g Ca(OH)2 to one graduated cylinder and shake [DO NOT MIX AHEAD OF TIME]
Flocculation begins within one minute and is complete in 4 – 5 minutes!
T1 min T15 min
T1 min T5 min
NO Flocculation material
WITH Flocculation material

13. Centrifugation
Spin sample very rapidly: denser materials go to bottom (outside)
Separate blood into serum and plasma
Serum (clear)
Plasma (contains red blood cells ‘RBCs’)
Check for anemia (lack of iron)
AFTER
Before
RBC’s
Serum
Blood
When you donate blood, the phlebotomist will check for anemia before drawing your blood. A small amount of blood will be taken from your fingertip into a thin glass tube. The blood may be placed in a centrifuge as described above to check for sufficient amounts of red blood cells. An alternate method is to drop the blood in a solution of copper sulfate. If the blood contains enough RBC’s the blood drop will sink to the bottom of the container, if it is not dense enough (lacks adequate number of RBC’s), the blood will float and you will not be allowed to donate blood. A
B C