Vocabulary Solublemiscible will dissolve in a solvent Insolubleimmiscible will not dissolve in a solvent Both of these terms require a solvent For example vitamin A is a fat soluble vitamin meaning it will dissolve in oils fat ID: 560587
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Slide1
Solubility and cleaningSlide2
Vocabulary
Soluble/miscible- will dissolve in a solvent
Insoluble/immiscible- will not dissolve in a solvent
~Both of these terms require a solvent
For example vitamin A is a fat soluble vitamin, meaning it will dissolve in oils (fat)
However it is insoluble in water
Water soluble (vitamin C) vitamins dissolve in water but are insoluble in oils.Slide3
Polarity of solvent
molecules and compounds can either be polar or nonpolar.
General rule- like dissolves like
polar dissolves polar; nonpolar dissolves in nonpolar.Slide4
Both polar and nonpolar
O
H
H
H
H
H
O=
O-
C
H
Methane
Hydrogen is always on the
outside so it has the same charge
Water
Hydrogen is on one side oxygen is
on the other.
-
+
soap molecule
This side is polar, two ends
with different charges.
This side is a long
nonpolar branch.
nonpolar
polar
this has a “Y” shape (3 ends)Slide5
Cleaning
Washing is normally dissolving the “stain” material.
Hard stains to get out are usually nonpolar.
Dry cleaners use a nonpolar solvent (that is a liquid) that doesn’t harm most materials (tetrachloroethene)
Soap is both polar and nonpolar.Slide6
Soap
The nonpolar “tail” sticks in the stain, dissolving it.
Leaving the polar “head” exposed.
Many
more soap molecules do this.
This is called a soap micelle.
So water encounters a sphere of nonpolar material with a polar “coating” on it (micelle).
the water picks up the “polar” sphere and sweeps it away.Slide7
Soap Micelle
Nonpolar
part
Polar
part
Soap molecule
Nonpolar part
of soap
“dissolves”
nonpolar stain
Nonpolar stain
Outside edge is
polar so it “dissolves”
in waterSlide8
Emulsions
This creates an emulsion (colloidal suspension of liquids)
Mayonnaise is another emulsion.
Mayonnaise is made up oil and vinegar (and other things) but an emulsifier allows them to mix in a colloidal suspension.Slide9
Polar stains
Water cleans polar stains itself.
Soap’s polar side does not clean polar stains.
Soap only works in conjunction with water.
The soap must be dissolved in the water to dissolve a nonpolar stain.Slide10
Hand sanitizer (
Purell
) vs. soap
The purpose of soap is to help you
remove
stain material.
Hand sanitizer is an alcohol based antiseptic.
The purpose is to kill any bacteria present.
The remains of the bacteria are still there.In a chemistry room, we need to remove any chemical that may irritate your skin. Therefore you should wash with soap and water after a labSlide11
More on Soap
Your body naturally secretes oil (sebum)
This oil can cover a polar stain and make it difficult to clean off.
Soap is very good at dissolving the oil off your skin, so you can clean what is underneath.Slide12
Detergents
Soaps are made from naturally occurring fats and sodium hydroxide.
Detergents are made from mixing crude oil products or synthetic oils and sodium hydroxide.
Detergents came into heavy use during World War II when oils were in short supply.Slide13
Which is better?
Soap will react with some ions in “hard water”, water with heavy metal ions, to form an insoluble film ~
soap scum
Detergents will not.
Soaps tend to be better for the environment (more biodegradable)
Soaps tend to be less harsh on your skin
We use detergents for nonliving things, and soap for bathing.Slide14
Solubility
~A measure of how soluble something is.
Nothing is completely soluble or completely insoluble.
Increasing the temperature normally increases the amount of a solid solute a solution can hold.Slide15
Gases dissolved in a liquid
Colder solutions hold more of a gaseous solute.
Heating a solution forces gases to come out of solution (pre-boiling bubbles)
Higher pressure solutions can hold more gases.
~Why a pop can fizzes when openedSlide16
Decompression Sickness
If you dive deep into the ocean (submarine or scuba) the pressure increases
More gases will dissolve in the fluids of your body
If you rise too quickly, gases dissolved in the fluids of your body will come out of solution
This painful and deadly situation is called decompression sickness or “the bends”Slide17
Saturation
Saturated solution- solution that has all the solute it can hold. If any more is added it will not dissolve.
Supersaturated solution- a soln. holding more solute than it should
Made by heating a solution to dissolve more solute and then cooling it.
If you disturb a supersaturated solution the solute will fall out of solution.Slide18
Solubility Curve
Graph of grams of solute
vs. temperature
g of solute
per 100 g
of water
Temperature (
o
C)
0 20 40 60 80 100
100
80
60
40
20
0
KNO
3
KCl
NaCl
NH
3