292 Step 4. Review the Knowledge You Need to Score High
- Measure the initial temperature.
- Measure the final temperature.
Calculations
The masses are converted to moles using the molar mass. The volumes of solutions may be
converted to moles using the molarity.
The mass of a solvent or solution may be calculated from the volume and density.
A total mass may need to be calculated by adding the individual masses together.
The change in temperature (ΔT) is calculated from the difference between the final and
initial temperatures.
The energy (joules or calories) is calculated by multiplying the mass times the change
in temperature times the specific heat (from a table).
The enthalpy change is calculated by dividing the calculated energy by the moles, mass,
or some other designated quantity.Comments
Any reaction or phase change may be used.Experiment 14: Qualitative Analysis of Cations and Anions
Synopsis
Solutions containing various ions are tested for the presence of certain specified ions. The
formation of colors, gases, or precipitates indicates the presence or absence of certain ions.
(See the Reactions and Periodicity chapter.)Equipment
beaker(s) centrifuge evaporating dish
funnel mortar and pestle Pt or Ni test wire
test tube(s) watch glassMeasurements
This is primarily an observation experiment. No precise measurements are needed.Calculations
No calculations are required.Comments
A wide variety of cations or anions may be used. Many of the results are a simple applica-
tion of the solubility rules.Experiment 15: Synthesis and Analysis of a
Coordination Compound
Synopsis
A coordination compound is usually synthesized from a transition metal ion that is in solu-
tion. The compound is filtered from the solution and tested in various ways to determine
the composition of the substance. (See the Reactions and Periodicity chapter.)