L4 - Volumetric Analysis

 VOLUMETRIC ANALYSIS

• the determination of the volume of a solution of known concentration required to react with a given amount of a substance to be analyzed.

• volume

• known concentration

 VOLUMETRIC ANALYSIS

• the determination of the —— of a solution of ——— required to react with a given amount of a substance to be analyzed

• It is used in determining the purity of drugs 

• Food industry 

  determination of salt, vit, and fatty acid content. 

• Water treatment 

  determination of contaminants and pH (acid and base titration - neutralization)

 VOLUMETRIC ANALYSIS IMPORTANCE

Food industry 

determination of salt, vit, and fatty acid content. 

Water treatment 

• determination of contaminants and pH (acid and base titration - neutralization)

• QUANTITATIVE CHEMICAL ANALYSIS

  known concentratio

  unknown solution

 TITRATION

• a common laboratory method of _____ where a solution of ____  is used to determine the concentration of an ______ .

 TITRATION

• a common laboratory method of QUANTITATIVE CHEMICAL ANALYSIS where a solution of known concentration (No. 2)  is used to determine the concentration of an unknown solution. (No. 1)

1. Analyte/Titrand 

2. Standard solution/ Volumetric Solution/ Titrant 

3. Indicator (end point)

PARTS OF A TITRATION SET-UP: 

Analyte

• The chemical substance being analyzed or the active constituent in the sample. 

• Analyte 25-30 mL

Standard solution

a solution which concentration is accurately known.

Indicator (end point)

a chemical which CHANGES COLOR at or very near the endpoint.

ENDPOINT (PRACTICAL) 

• point during a titration when an indicator shows that the AMOUNT OF REACTANT necessary for a complete reaction has been added to a solution

• Equivalence point or stoichiometric point or theoretical endpoint 

    -   is the theoretical point at which equivalent amounts of each substance have reacted 

NEUTRALIZATION

reaction between an acid and a base to form salt of water

PRECIPITImetry

• reactions that from an insoluble precipitate (Salting out)

• May precipitation bec due common ion effec

COMPLEXOmetry

• reaction between metal ions and a  ligand (ability to bind)

REDOX TITRATION

• reaction that involves the transfer of electrons

Indicator (end point)

• Chemical substance, which changes color at or very near the endpoint. 

TS or Test Solutions 

INDICATORS

REFERRED: 

INDICATORS

USED:   avoid errors during titration 

0.05%

INDICATORS

USUAL CONCENTRATION: —— , with 0.1 mL (2 drops) to 0.2 mL (4 drops) of indicator used for 10 ml of the analyte.

0.1 to 0.2 mL

INDICATORS

 0.05%, with ——- of indicator used for 10 ml of the analyte. 

EQUIVALENT 

number of moles of reactive unit in a compound which reacts or takes the place of one mole of Hydrogen ion

EQUIVALENT WEIGHT 

weight that is chemically equivalent to the reacting power of one of one atomic weight of hydrogen.

TITER

• strength in grams equivalent to milliliter of standard solution or the weight of a substance chemically equivalent to 1 ml of a standard solution. 

 NORMALITY

• no. of equivalents of solute per liter 

MOLARITY

• refers to the no. of moles of solute per liter of solution

 STANDARD SOLUTION

• a solution of known concentration or a solution whose exact concentration is known 

• HCl

• H2SO4

• HClO4 

STANDARD ACID SOLUTION 

• NaOH

• KOH

• CH3ONa

STANDARD ALKALI SOLUTION 

STANDARDIZATION

Process of determining exact concentration of a solution.

PRIMARY standard

chemically pure solid substance almost 99.9% pure used in the standardization of a solution

SECONDARY standard

• substance that is not necessarily pure but whose exact purity is known. 

• A standard solution is a commonly used secondary standard. 

• Common practice 

  - to standardize only one of the solutions by using a primary standard and the other is standardized by using a secondary standard.