ALKALIMETRY Flashcards
The strength of an acid
solution is determined by
titrating it against a standard
base solution or determining the
strength of an alkali solution by
titration with a standard acid
solution.
Principle of Acid – Base
Titration
is used to monitor
the reaction
pH indicator
reaction
usually occurs between acid and
base, hydroxide ions and hydrogen
protons, resulting in the formation
of water
neutralization
re chemical processes
whereby an amount of an acid has reacted with
an equivalent amount of a base with the
production of salt and water.
Neutralization reactions
is the measurement of basic
substances by titration with
a standard acid
ACIDIMETRY
involves the determination
of acidic substances by
titration with a standard
base solution.
ALKALIMETRY
any substance which releases H ions in water solution
ARRHENIUS ACID
any substance which releases OH ions in water solution
ARRHENIUS BASE
any substance which donates a proton
BRONSTED LOWRY ACID
any substance which accepts a proton
BRONSTED LOWRY BASE
any substance which can accept an electron pair
LEWIS ACID
any substance which can donate an electron pair
LEWIS BASE
is any substance which in water ionizes to give hydrogen ions
(hydronium ions*)
ACID
is any substance which in water ionizes to give hydroxyl ions
BASE
is the combination of the proton and hydroxyl ion to
form the water molecule.
NEUTRALIZATION
by-product of neutralization
SALT
NEUTRALIZATION
Based on Media (Solvent) Used
Aqueous titrimetry
Non-aqueous titrimetry
use water as the solvent for
dissolving the analyte samples for the
titration.
Aqueous titrimetry
the concept of acids and bases has been
extended to include solvents other than
water, acids other than proton donors, and
bases other than hydroxyl ions donors.
These are considered, on nonaqueous
titrimetry
Non-aqueous titrimetry
Non-aqueous titrimetry use ______ for dissolving the
sample.
organic solvents
Strong Acid + Strong Base
Phenolphthalein, methyl red, methyl orange
Weak Acid + Strong Base
Phenolphthalein
Weak Acid + Weak Base
No indicator
Strong Acid + Weak Base
Methyl red
Weak Base + Salt
Crystal violet, Quinaldine red, malachite green
Relatively Strong Base
Methyl red, methyl orange
Weak acid
Azo-violet, o-nitro-aniline (very WA)
Strong Acid
Thymol blue
BASES’ BURETTE
MOHR’S BURETTE
ACIDS BURETTE
GEISSLER’S BURETTE
The most common application of acid-base
titrations is
determining an unknown analyte’s acid
or base concentration
_______ is carried out with ACID-BASE TITRIMETRY
Quantitative chemical analysis
Pharmaceutical applications of Acid-Base
Titrimetry
A barbiturate, aspirin, and amino acid
An environmental analysis can be conducted with
it.
Application of Acid-Base
Titrimetry
percentage potency, strength or
percentage purity of a drug or preparation.
- amount per 100
% assay
Types of Titration Based On The
Number of Volumetric Solution
DIRECT AND RESIDUAL/BACK TITRATION
Titrant is added into the analyte until chemical
equivalent amounts of them reacts together
DIRECT
Described as the amount of
volumetric solution in excess. The excess is back titrated with
another volumetric solution
RESIDUAL OR BACK TITRATION
ONLY 1 VOLUMETRIC SOLN/STD. SOLUTION
DIRECT
USES 2 VOLUMETRIC SOLN. (VISS)
1 or more std. sol’n., involve addition of excess std. sol’n. & the
excess is back titrated w/ another std. sol’n
RESIDUAL
WHY Residual Titration?
❖ Volatile
❖ Sample is insoluble in water
❖ Reaction with standard solution is
slow
❖ Sample does not give a distinct
endpoint with an indicator by
direct titration (No sharp
endpoint)
can be calculated by dividing the mass
of the pure chemical by the total mass of the sample, and then multiplying
this number by 100.
Percentage Purity
s carried in the same manner as
the actual test BUT without the sample
Blank test
Blank test are Performed to correct errors due to
- the presence of impurities in the reagents
- changes in volume at different temperature
- absorption of carbon dioxide by the alkali
- by the alkalinity imparted by the glass
ml in the blank titration is ml of acid =
total base
ml in actual is ml of acid =
base found in excess
l of acid that reacted with sample =
ml of
the base that reacted with the sample
is the analysis of an acid , acid
salt or other acidic substance
Alkalimetry
f using an accurately measured volume
of a standard alkali solutions
DIRECT
if the process requires adding an
excess of the standard alkali solution and
determining the amount in excess by residual
titration with standard acid solution
RESIDUAL
