Download The Nature of Solubility

The Nature of
Solubility
Structure of Water
Properties of Solutions
Factors Affecting Gas and Solid Solubility
What is a Solution?
• In your science notebooks, write down the definition of a solution as
it applies to science.
• Yes, a solution is also the answer to a problem, but in science…
• Solutions:
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A solutions is a mixture of materials.
One material is usually a fluid.
A fluid is a material that flows, such as a liquid or a gas.
The fluid of a solution is usually the solvent.
The material other than the solvent is the solute.
In science, we say that we dissolve the solute into the solvent.
• What are some examples of solutions you use daily?
What is a solute?
• Solutes:
• The material (or chemical) present in the lesser amount
• The substance which dissolves in the solvent to form a solution
• Any reagent that undergoes a change in state when it forms a
solution
What is a solvent?
• Solvents:
• The material (or chemical) present in the greater
amount
• The substance in which the solute dissolves to form a
solution
• The most widely used solvent is water.
Some Properties of Solutions:
• The mixture does not separate upon standing.
• Once the solute and solute are completely mixed, the mixture
is homogeneous.
• This means you could take a sample from anywhere in the
solution and the proportions of the materials will be the same.
• The mixture will be transparent. (This doesn’t mean it is clear,
or colorless. It means that the mixture is not cloudy.)
The Structure of Water
• Every water molecule has one oxygen atom and two
hydrogen atoms.
• The chemical formula is H2O.
• The hydrogen atoms are 105° apart from each other.
• The hydrogen atoms have a positive charge and the
oxygen atom has a negative charge. Why does that
matter? Like charges repel, unlike charges attract.
• There is an unequal distribution of charges on the water
molecule. This makes the water molecule a polar
molecule.
Polarity
• “Like dissolves like”
• One end of the water molecule is more negative (oxygen), and the
other is more positive (hydrogen).
• The partial negative end of the oxygen atom is attracted to the
partial positive end of the hydrogen atom on an adjacent molecule.
• The hydrogen bonds give water its unique properties.
Factors Affecting Solid Solubility
• The solubility of a solute at a particular
temperature is the number of grams of a solute
which must be added to 100 g of a solvent to
produce a saturated solution.
• The solubility of a solid increases with
temperature.
Universal Solvent
• Water is often described as a universal solvent. It is capable of
dissolving a variety of different substances.
• Water can dissolve polar or ionic substances.
• Water cannot dissolve nonpolar substances.
• It is water's chemical composition and physical characteristics
that make it such an excellent solvent.
• Water, as a universal solvent, is important to every living thing
on Earth.
• Wherever water goes (through the air, ground, or our bodies), it
carries valuable chemicals, minerals, and nutrients.
Unique Properties of Water
• Water is the universal solvent.
• It exists naturally on Earth as a solid, liquid, and gas.
• It exists at room temperature as a liquid.
• In its solid state (ice) is less dense than liquid water.
• It has a high surface tension. (That is why there can be water
drops and waves in the ocean.)
• It has a high specific heat. (It keeps the beach cool during the
day and warm at night.)