Analytical Chemistry Practical Final Exam

Volumetric Analytical Techniques

• Redox is a type of volumetric analytical technique where electrons are transferred from a reducing agent (e.g. oxalic acid) to an oxidizing agent (e.g. potassium permanganate).

Laboratory Equipment

• Centrifuge: a device used to separate two or more substances (liquid and solid) that do not react chemically, resulting in two distinct layers: supernatant (upper layer) and precipitate (lower layer).

Measuring Concentration

• Photometer: a device used to measure the concentration of a solution by measuring its absorbance of light at a specific wavelength.

Absorbance and Wavelength

• Absorbable curve: a graph that illustrates the relationship between the absorbance of a colored solution and its wavelength at a constant concentration.

Practical Considerations

• Temperature control: water bath temperature should not boil, as this can cause the reduction of KMnO4 before the start of the reaction with H2C2O4.

Redox Reactions

• Oxidation and reduction occur concurrently, with the number of electrons lost in oxidation equal to the number of electrons gained in reduction.

Standard Solution Preparation

• NaOH cannot be prepared as a standard solution because it is a hygroscopic compound that absorbs CO2 and H2O from the atmosphere.

Precipitate Treatment

• Precipitates are washed with NH4OH to remove impurities.