5 Steps to a 5 AP Chemistry

Equipment

analytical balance beaker(s) Erlenmeyer flask

evaporating dish pipet spectrophotometer

test tube(s) or cuvettes volumetric flask

Measurements

Synthesis

Quantities of the reactants are weighed and added to a beaker. A solvent may or may not

be present initially.

The mass of the product is determined by weighing.

Analysis

Weigh a sample of the compound into a volumetric flask, and dilute to volume.

Use a pipet to measure samples to be diluted.

Measure absorbency of the diluted solutions with a spectrophotometer. This may or

may not require the separate construction of a calibration curve.

Calculations

Calculate the moles of each reactant from the masses and molar masses. Then calculate the yield

based on the limiting reagent. The mass of the product, determined at the end of the synthesis,

divided by the mass calculated from the limiting reagent times 100%, gives the percent yield.

There are numerous possible analysis calculations.

Comments

Commonly synthesized coordination compounds include K 3 [Fe(C 2 O 4 ) 3 ] and [Co(NH 3 ) 6 ]Cl 3.

Experiment 16: Gravimetric Analysis

Synopsis

The amount of a substance present in a sample is determined by taking a solution containing

that substance and precipitating a compound containing that substance. The precipitate is

then dried and weighed. (See the Stoichiometry chapter.)

Equipment

analytical balance beaker(s) crucible and cover

desiccator drying oven funnel

Meker burner support stand triangle crucible support

Measurements

1. A sample is weighed and then dissolved.


2. Excess (unmeasured) reactant is added to the solution to form a precipitate.


3. The empty crucible and cover are weighed.


4. The crucible and cover containing the dried precipitate are weighed.

Calculations

The mass of the precipitate is found as the difference between measurements 3 and 4.

The mass of the dried precipitate is converted into moles by using the molar mass. Through

use of a stoichiometric ratio, the moles of precipitate are converted to the moles of the substance

of interest. The moles of this substance are converted to its mass using the molar mass.

Experimental  293