Quantitative Chemical Analysis and Leather Technology Experiments Flashcards

Vocabulary flashcards covering principles, reactions, indicators, standards, and experimental results from analytical chemistry lab experiments on lime, deliming agents, pickle liquor, chrome tanning materials, and salts.

Back Titration Method for Total Lime

A technique where a lime sample is dissolved in a known excess of standard $HCl$, and the remaining excess acid is back-titrated against standard $NaOH$ using a phenolphthalein indicator.

Potassium Hydrogen Phthalate (PHP / KHP)

A primary standard used to standardize $NaOH$ solution by titrating to a pale pink end-point in the presence of phenolphthalein indicator.

Formaldehyde Reaction with Ammonium Chloride

A reaction where neutral formaldehyde reacts with $NH_4Cl$ to form hexamethylenetetramine and release free $HCl$ according to $6HCHO + 4NH_4Cl \rightarrow (CH_2)_6N_4 + 4HCl + 6H_2O$, which is then titrated with alkali.

Silver Chromate ($Ag_2CrO_4$)

A brick-red precipitate formed at the end point of argentometric precipitation titration when excess $Ag^+$ ions react with potassium chromate indicator ($CrO_4^{2-}$).

Hexamethylene Tetramine (Urotropine)

A complex formed when formaldehyde ($HCHO$) reacts with ammonium sulfate $(NH_4)_2SO_4$, liberating free sulfuric acid ($H_2SO_4$) for titration against standard $NaOH$.

Polyhydroxy Compounds in Boric Acid Titration

Organic compounds such as glucose or glycerol added to weak boric acid ($H_3BO_3$) to form a complex that increases acidity, enabling direct titration with standard alkali using phenolphthalein.

Basic Chromium Sulphate (BCS) Analysis Principle

Method to estimate chrome percentage and basicity based on hydrolysis of basic chromium salt 2Cr(OH)SO_4 + 4H_2O \rightarrow 2Cr(OH)_3\rightdownarrows + 2H_2SO_4 and titration with $NaOH$.

Estimation of Chromium in Leather Principle

An iodometric titration where trivalent chromium ($Cr^{3+}$) in leather is oxidized to hexavalent dichromate ($Cr_2O_7^{2-}$) using an acid mixture, followed by reaction with $KI$ to liberate iodine ($I_2$) for titration with standard $Na_2S_2O_3$.

Sodium Sulfide ($Na_2S$) Estimation Method

Method where sulfide is precipitated as zinc sulfide ($ZnS$) using zinc acetate, reacted with $HCl$ and excess $I_2$, and the unreacted iodine is back-titrated with standard $Na_2S_2O_3$ using starch indicator.

Analysis of Pickle Liquor

Procedure to determine $H_2SO_4$ content by titration with standard $NaOH$, followed by salt ($NaCl$) determination in the neutralized liquor via titration with standard $AgNO_3$ using potassium chromate indicator.

Available Lime Analysis Result

The percentage of lime content present in the given sample as CaO in the available lime estimation experiment is $29.97\%$.

Pickle Liquor Analysis Results

The amount of $H_2SO_4$ present in pickle liquor is $1.21\%$ and the amount of $NaCl$ present is $27.6\%$.

Sodium Sulphide Estimation Result

The percentage of sodium sulphide estimated from the sample solution is $40.43\%$.

Chrome Oxide in Leather Result

The percentage of chrome oxide present in the chrome tanned leather sample is $2.59\%$.

Basic Chromium Sulphate (BCS) Results

Experimental results showing $1.712\%$ chromium as $Cr_2O_3$, $6.6887\%$ sulphate combined with chromium, and a basicity of $47\%$.

Boric Acid Purity Result

The percentage amount of boric acid present in the given sample as $H_3BO_3$ is $26.95\%$.

Ammonium Sulfate Purity Result

The percentage of ammonium sulfate $(NH_4)_2SO_4$ present in the given sample is $89.207\%$.

Sodium Chloride Purity Result

The percentage purity of sodium chloride ($NaCl$) present in the given sample is $65.46\%$.

Ammonium Chloride Deliming Agent Result

The percentage of ammonium chloride ($NH_4Cl$) present in the deliming agent sample is $102.98\%$.

Total Base Lime Sample Result

The percentage of lime content present in the sample as CaO in the total base analysis experiment is $59.25\%$.

Titration Method

A quantitative chemical analysis method used to determine the concentration of an identified analyte by adding a volume of titrant of known concentration until a reaction is complete.

End Point in Titration

The point in a titration where the amount of titrant added is exactly enough to completely react with the analyte.

pH Indicator

A substance that changes color at a specific pH level, used to signal the endpoint of a titration, such as phenolphthalein.

Standard Solution

A solution of known concentration used in titrations and other chemical analyses.

Back Titration Principle

A method used when the analyte is insoluble, involving the reaction of a known excess of reagent and subsequent titration of the excess.

Iodometric Titration

A method of titration used to determine halides or other substances that can react with iodine, often involving the reduction of iodine back to iodide.

Complex Formation in Titration

The process in which a reagent reacts with one or more components in solution to form a more stable complex, which alters the properties of the reactants.