5 Steps to a 5 AP Chemistry

Measurements

1.the volume of the solution of acid or base using a pipet

2.the initial reading of the buret

3.intermediate readings from the buret

4.the final reading of the buret

5.the pH of the solution at various times during the reaction

Calculations

The volume added is calculated by taking the difference between measurement 2 and either

measurement 3 or 4.

A plot of pH versus the volume added is made. This graph or the difference between

measurements 2 and 3 gives the volume of titrant.

The volume of titrant is converted to liters.

The pipeted volume is converted to moles by multiplying the liters of solution by

its molarity. The moles of titrant are determined using the mole ratio in the balanced

chemical equation for the acid–base reaction. The molarity of the solution is calculated by

dividing the moles of titrant by the liters of titrant used.

Comments

It does not matter whether an acid is titrated by a base or vice versa.

Experiment 8: Oxidation–Reduction Titration

Synopsis

The concentration of either an oxidizing or a reducing agent may be determined by titrat-

ing a solution of an unknown concentration versus a solution of a known concentration or

containing a known mass of solute. (See the Stoichiometry chapter.)

Experimental  287

Acid (or base)

and indicator

Stopcock

Buret containing

base (or acid)

Figure 19.3 General acid–base titration set-up