Transcript Solutions and Solubility

Solutions and Solubility
Mixtures
• Solutions are a type of mixture, so to
understand solutions, first we have to know
what a mixture is…
• A mixture is a combination of two or more
substances. Each substance keeps it’s own
properties, even though it is mixed with
another substance. They do not combine to
form a new chemical substance
Mixtures
• Mixtures are all around us: raisin bran, cakes,
soda, soup, salad, rocks, sweet tea, trail mix,
etc.
Mixtures
• There are 2 types of mixtures:
– Homogeneous mixtures: everything in the
mixture is even spread out and thoroughly mixed
• If you took 2 spoonfuls of this type of mixture, they
would be exactly alike
– Heterogeneous mixtures: there is more of 1
substance than another and they are not evenly
spread out and thoroughly mixed
• If you took 2 spoonfuls of this type of mixture, they
would not be exactly the same
Solutions
• Solutions are a type of homogeneous mixture
• We call it a solution when 1 substance dissolves
into another substance
– An example is sweet tea…the sugar dissolves in the
tea
– Another example is soda…the carbon dioxide dissolves
in the liquid soda
– Another example is air…the oxygen dissolves in the
nitrogen
– Another example is a metal alloy like steel, made of
iron and carbon
Solutions
• We give special names to the substances in a
solution
– The material that is doing the dissolving is called
the solvent.
• So many things dissolve in water that they call it the
“Universal Solvent.” It is the most common solvent
– The material that is being dissolved is called the
solute.
– There is usually more solvent in a solution than
solute
Solutions
• With our sweet tea example, the tea would be
the solvent and the sugar would be the solute.
Solutions
• By now you should see, solutions aren’t
always solids and liquids
Gas-Gas
Air
Gas-Liquid
Carbon Dioxide in
Soda
Liquid-Liquid
Gasoline
Liquid-Solid
Dental Fillings
Solid-Solid
Sterling Silver
Solubility
• Solubility is the amount of solute that can be
dissolved in a specific volume of solvent under
certain conditions
– Solubility basically tells us how well the solute will
dissolve in the solvent
Solubility
• Several factors can affect solubility
– Temperature of the solvent
• You can dissolve more sugar in hot tea than you can in
cold tea
• You can dissolve less gas in a hot liquid than in a cold
liquid
– Pressure of the system
• A closed soda can has more carbon dioxide in it than an
open one because the closed can is under pressure
Solubility
• The Chemical Nature of the Solvent
– Some solvents, like water, naturally dissolve more
substances than other solvents do.
• Stirring and Particle Size can affect how fast a
solute dissolves in a solvent
Saturation
• A solvent is said to be “saturated” when it is
holding as much solute as it possibly can and if
you add any more solute, it will start to come
out of solution
– An example is when you have extra sugar at the
bottom of your sweet tea. The tea can’t hold any
more sugar…it is saturated.
• Solubility is not affected by the amount of
matter present. It is just like density, melting
point and boiling point in that way
References
• www.chem4kids.com