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from yesterday
Please write the ORANGE words
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Solvents and Solutes

1)
2)


Solution - a homogenous mixture, that is
mixed molecule by molecule; made of:
a Solvent - the dissolving medium
a Solute - the dissolved particles
Aqueous solution- a solution with water
as the solvent.
The solvent dissolves the solute
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Examples:
1. the Solute
A solute is the dissolved substance in a
solution.
Salt in salt water
Sugar in soda drinks
Carbon dioxide in soda drinks
2. the Solvent
A solvent is the dissolving medium in a
solution.
Water in salt water
Water in soda
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Solutions
 Keep
in mind that solutions do
not have to contain water
 Solvents and solutes can be
gases, liquids or solids
 Examples: air (Gas in a gas) and
jewelry (alloy: solid in a solid)
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Solvents
There are a tremendous
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number of solutions we use in our daily lives!
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
Standard 6b - Students know how to
describe the dissolving process at the
molecular level by using the concept of
random motion
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The Water Molecule

Water is a simple tri-atomic molecule, H2O
molecule due
to its shape and the
electronegativity of O and H.
 Water
is a polar
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The Water Molecule
δ is the lowercase Greek symbol delta
δ+water
means
a a
δ- means a
Thus,
has
partial
partial
partial negative end
positive
negative
(0xygen)
and a
charge
δcharge
partial
positive end
(Hydrogen), and it
O
is called “polar”
H
H
because of these
δ+
δ+
areas of difference
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Aqueous Solutions

Water dissolves ionic compounds and
polar covalent molecules very well.
The rule is: “like dissolves like”
 Polar dissolves polar.
 Nonpolar dissolves nonpolar.
 Oil (hydrocarbons) is nonpolar.
– Oil and water don’t mix.
 Salt is ionic –dissolves in water.

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The Solution Process
 Solvation
- the process by which the
positive and negative ions are
surrounded by the solvent and dissolve.
 To form a solution the solute particles
(ions, atoms or molecules) must
separate from each other and solute
and solvent must mix.
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How Ionic solids dissolve in water
These ions have been pulled away from the
main crystal structure by water’s polarity.
H
H
H
H
H
These ions have been
surrounded by water,
and are now dissolved!
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Example: Salt in Water
 The
solvent and solute particles are in
constant random motion
 The water molecules “bump” into the
ions of the NaCl
 Water 1) breaks the + and - charged
pieces apart, and 2) surrounds them.
•
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Salt dissolving in Water
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Solids will dissolve if the attractive force of
the water molecules is stronger than the
attractive force of the crystal.
 If not, the solids are insoluble.
 Water dissolves other polar compounds
that have O-H bonds.
 Non-polar solvents dissolve non-polar
compounds – i.e. gasoline (non-polar can
dissolve oil (also non-polar)

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Concentrated vs.
vs. Dilute
Dilute
Concentrated
Lots of solute, but
little solvent
Lots of solvent,
but little solute
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