|In many acid-base reactions, the equilibrium is displaced
completely toward the product side. These reactions may be considered quantitative
and can be used as the basis for the analysis of the amount of acid or
base in a given sample. The process is termed volumetric analysis.
|The requirements are:
1) Only a single, specific reaction must take place between the unknown substance and the known substance used for the analysis.
|2) The unknown substance must react completely and rapidly
the added standard reagent. ie; it must be a quantitative reaction.
|3) An indicator or method must be available to signal when
unknown substance has reacted with the added standard reagent.
|The usual objective is to determine the mass or percentage
qualitatively identified component in a sample whose quantitative
is unknown. If the sample is a solution, the objective may be to
its molar concentration.
|An acid-base titration is just a method by which we can
a volumetric analysis. The concentration of an acid-base solution may
determined by measuring the volume of the base of known concentration
to react completely with a specific volume of an acid solution.
|Standard solution: A solution of known
Titration: the process of adding the standard solution from a graduated tube in controlled amounts.
Buret: a graduated tube with a dispensor control at the bottom.
Stoichiometric Point: the point at which equal molar quantities of reactants are present.
Chemical Indicators: a chemical that will change colour at or very near the ph of the stoichiometric point.
Endpoint: The place in the titration when the indicator
|The indicator used, should in theory coincide with the
point of the reaction.
|A 0.660 mol/L NaOH solution is used to determine the molar
of H2SO4 solution. What is the molarity of the
20.0 mL of which is just neutralized by 36.0 mL of the standard base?
|This is a standard problem which can be
|MaVa = MbVb
is the molarity, V is the volume, a is 'of the acid', b
is 'of the base'.
|Therefore Ma = Mb * Vb =
mol/L * 36.0 mL = 1.19 mol/L
Va 20.0 mL
|1. What is the molarity of a hydrochloric acid solution,
of which is just neutralized by 48.0 mL of 0.100 mol/L NaOH?
2. How many mL of 0.100 mol/L HCl are required to neutralize 25.0 mL of 0.100 mol/L Ba(OH)2?