Analytical Chemistry (questions and correct answers)

ANALYTICAL CHEMISTRY correct answers Branch of chemistry that deals with the separation, identification and composition of matter Gravimetric Method correct answers Measurement of mass of substance that is chemically related to the analyte Volumetric Method correct answers Measures the volume of solution necessary to read completely with the analyte. Spectroscopic Method correct answers Measures the electromagnetic radiation produced by the analyte or its interactions with it. Electroanalytic Method correct answers Measures the electrical properties of the analyte such as current, potential, resistance, and amount of charge Kjeldahl Method correct answers Determination of Organic Nitrogen (Amines, Amides, Nitriles and Nitro Group: %N or %Protein Double Indicator Method correct answers To determine the composition of a soda ash sample. Two indicators (one alkaline range one acidic) Example: Phenolphthalein endpoint (Na2CO3 and NaOH) and methyl red endpoint (Na2CO3 and NaHCO3) Argentometric titration correct answers Titration with Silver Nitrate AgNO3 Mohr Method correct answers Direct method for halides and cyanides; Titration is carried out between pH of 7-10. Usually, a low concentration of chromate is desired to detect the end point clearly since a chromate ion imparts an intense yellow color. Volhard Method correct answers For the formation of a colored complexion; Direct method for silver; Indirect method for halides; Titration is carried out in acidic condition to hasten precipitation of ferric ion to its hydrated oxide form. Fajan's Method correct answers For the formation of a colored adsorption complex; same as Mohr's but uses DCF dichlorofluorescein; between pH 4-7, dextrin is added to prevent excessive coagulation of the AgCl precipitate. Liebig Method correct answers Determination of Cyanide, carried by the dropwise addition of AgNO3 in a solution of a cyanide forming a soluble cyanide complex of silver Permanganate Process correct answers Oxidation-Reduction Titration with KMnO4; Self-indicating. Dichromate Process correct answers Cr2O72-+6e- - 2Cr3+