To determine the concentration of a saturated solution of NaCl, sodium chloride, in moles per liter.
To compare the relative solubility of two solutes in two solvents.
To study double replacement reactions, specifically, the effect of adding
solutions containing selected negative ions (anions) to solutions containing
positive ions (cations) of metals in group II (Mg, Ca, Sr, and Ba).
To observe the energy changes, which occur when a substance dissolves in
The solubility of a solute is the maximum amount of solute, which
can be dissolved in a given quantity of solvent or solution. The solubility
of a substance is often expressed in moles of solute per liter of solution.
Substances are considered to have a high solubility if more than 0.1 mole can
dissolve in one liter of solution.
A saturated solution is a solution,
which contains the maximum amount of solute that can dissolve at a given temperature.
In general, solubility increases as temperature increases. The amount of solute
that is dissolved in a solution is expressed as concentration. The unit of concentration
is referred to as molarity, M. We can express
molarity in an equation form
The amount of solute, which can dissolve in a given amount of solvent
depends on the nature of the solute and solvent. In general, "Like
dissolves like", describes the general principle of solubility (i.e.
polar solvents dissolve polar solutes and non-polar solvents dissolve non-polar
solutes). Thus, mineral acids, bases and salts, which are polar, tend to be
much more soluble in water, which is polar, than in solvents such as ether or
hexane, which are essentially non-polar. Conversely, non-polar substances tend
to be only slightly soluble in water, but very soluble in non-polar solvents.
Liquids that dissolve in one another are said to be miscible.
Again, the general principle "Like dissolves like"
dictates whether two liquids are miscible. If both liquids are polar then the
liquids are miscible. If the two liquids are nonpolar then the liquids are miscible.
a polar liquid and a nonpolar liquid are immiscible. They repel one another
and separate into two layers. Two liquids will be studied in this lab,
water and hexane. Water is a polar liquid. Hexane is a non-polar liquid.
The specific gravity of water is 1.0. The specific gravity of hexane is
Which layer do you think is on top?
A matrix of solutions will be studied in this lab. We will be
mixing solutions together and observing whether reactions occur. The type of
reaction we will be studying is known as Double Replacement
Reactions or Metathesis Reactions. When
two solutions are mixed, the ions in the mixture may combine to form a compound,
which has a low solubility in water. In such a case, a precipitate will appear.
The dissolving process may be endothermic (with a net absorption
of energy) or exothermic (with a net release of energy).