Download Introduction To Solutions

Introduction To Solutions
Aretina Chan
A solution is a mixture in which particles of a solute are dissolved in the particles of a solvent
A homogenous mixture is a mixture in which all the components are evenly distributed.
A heterogeneous mixture is a mixture in which all the components are not uniform or have other regions
with different properties.
Miscible liquids can mix together
Immiscible liquids cannot mix together
Saturated solution is a solute that dissolves until it is unable to dissolve anymore, leaving undissolved
substances at the bottom.
Unsaturated solution is a solution that completely dissolves, leaving no remaining substances.
Supersaturated solution is a solution that contains more undissolved solute than the saturated solution
because of it’s tendency to crystallize and precipitate.
Water’s properties

In the solid state, the particles of matter are usually much closer together than they are in the liquid
state. So if you put a solid into its corresponding liquid, it sinks. But this is not true of water. Its solid
state is less dense than its liquid state, so it floats.

Water’s boiling point is unusually high. Other compounds similar in weight to water have
a muchlower boiling point.

Another unique property of water is its ability to dissolve a large variety of chemical substances. It
dissolves salts and other ionic compounds, as well as polar covalent compounds such as alcohols and
organic acids.
Why can we dissolve solvents in solutes?
We should first keep in mind that not ever solvent can be dissolved every solute
like gas. But liquid solvents have a ton of molecular interactions so the structure
of their molecules determine whether a substance will dissolve and how well it
will dissolve. Polarity is the key, for a substance to dissolve, it needs to interact
favorably with the solvent which can only happen if they have similar polarities
this allowing the water molecules to surround the charged particles of the salt
(right) with oppositely charged ends of the water molecules.
Left: NaCl crystals
Right: NaCl in water
Why do solutes dissolve faster when heat is applied?
When substances are heated, particles increase their molecular motion. Increase molecular motions
competes with the attraction between solute molecules and tends to make them come apart more easily.
Increased molecular motion causes more solvent molecules to contact solute molecules and pull on them
with more force, usually resulting in more dissolving.
Coke Burps
We all know CO2 makes sodas tastier, but how do we get the gas inside the can? Gas
gets dissolved in a solution under pressure, although it’s not just the pressure outside of
the solvent but also the partial pressure in the solute (a.k.a the portion of pressure
caused by the gas we’re interested in, CO2). Gas molecules want to escape the solution
so they will create an upward pressure on the surrounding gas, in order to keep the
CO2 dissolved, the partial pressure of carbon dioxide in the gas and outside the
solution has to be equal to or higher than the pressure of the CO2 molecules pushing
their way out of the solution. This explains why CO2 molecules rush out of soda cans
when opened. So to get the CO2 into the can, all you need to do is increase the pressure
of CO2 outside the liquid.
Textbook: pg 366-380 HW: Pg 381 #1-9