5 Steps to a 5 AP Chemistry

Measurements

In some cases, the distance a spot travels on the chromatographic media is measured. This

requires the use of a ruler.

Calculations

There are usually no calculations.

Comments

Instead of an ion exchange resin or silica gel, it is possible to use filter paper as a chromato-

graphic medium.

Experiment 19: Properties of Buffer Solutions

Synopsis

Buffer and non-buffer solutions are prepared. The pHs of these solutions are determined before

and after other substances—usually acids or bases—are added. (See the Equilibrium chapter.)

Equipment

beaker(s) pH meter pipet

volumetric flask

Measurements

1. volumes of the pipeted solutions


2. pH of various solutions

Calculations

The concentrations of the solutions may be calculated by using the dilution equation.

Concentrations may then be converted to moles by multiplying the concentration by the

liters of solution. This procedure applies to buffer components or any reactant species.

The moles of substances may be determined from the initial moles and stoichiom-

etry. Combined with the liters of solution, these may be used to determine the final

concentrations.

Experimental  295

Capillary tube

(a) Spotting the Chromatography Paper

Solvent

(b) Chromatography Development Jar

Figure 19.4