What is a solution? A homogeneous mixture of 2 or more substances.
Components of a solution
Solute (substance being dissolved ex. Sugar) + solvent
(substance holding the solute ex. Water)
Alloys- homogeneous mixtures of metals ex. Brass, steal
Liquid solution- a solution in which the solvent is a liquid. Rules for
liquid solutions:
Liquid solutions do not separate when standing
Liquid solutions pass through a filter
Liquid solutions do not disperse light. They are transparent
Water solution- a solution in which the solvent is water. Types of water
solutions:
Saturated solution- a solution in which the solvent is dissolving the
maximum possible solute at that temperature
Unsaturated solution- a solution in which the solvent can still dissolve
more solute at that temperature. Precipitation is when solid solute
falls out of the solution as it cools down.
Supersaturated- *rare exception* the solvent is actually dissolving more
solute than it should at that temperature. Very unstable and tends to
precipitate when disturbed.
Solubility curves
Factors affecting solubility
Temperature- as temperature increases, generally solubility of liquid
and solid solutes increases in water. But the solubility of gaseous
solute decreases at higher temperature.
Volume of solvent- more solvent can hold more solute.
Pressure- increasing pressure on the surface of a solution increases the
solubility of gaseous solutes. No affect on solubility of liquid and
solid solutes.
The nature of the solute and solvent “Like dissolves like”. Molecules
that are similar dissolve well in each other.
Polar and most ionic solutes dissolve well in water (dipole).
Because most ionic bonds break in water. For example, a water
molecule has one positive side and one negative side. So when a
polar ion comes to dissolves in it, the positive and negative sides
of the ion split and go to opposite sides of the water. And
this is why we say it dissolves well.
Non-polar solutes dissolve well in non-polar solvents ex. Benzene
and oil.
Predicting which ionic solutes are water-soluble.
Ionic and polar solutes that have a positive and a negative side dissolve
best in a polar solvent such as water.
Non-polar solutes that are nonsymmetrical do not dissolve in water, only
non-polar solvents like oil and benzene.
Electrolyte- a compound that when added to water “breaks” into + and – ions
and as a result, conducts electricityà
any water soluble ionic compound (Table F)
DILUTE SOLUTION
CONCENTRATED SOLUTION
Weak
Strong
Little solute or lots of solvent
Lots of solute or little solvent
·Table F
oNaHCO3 ;Soluble or insoluble? It is
soluble because on Table F, in the chart labeled “ions that form soluble
compounds”, the first rule says that any compound with an element from group 1
is soluble. Na is in group 1 and therefore soluble.
oAgCl; Soluble or insoluble? First we see on the
first chart that halides (Cl, Br, I) are soluble. But in the “exceptions” column
it says that the compound is not soluble is combined with Ag, Pb, or Hg2.
therefore AgCl is insoluble.
