Qualitative Inorganic Analysis of Aluminum Sulphate
Chemical Composition & solubility
Before understanding qualitative Inorganic Analysis of Aluminum Sulphate, Let’s understand chemical composition and solubility property of Aluminum sulphate, commonly known as alum, is a widely used chemical compound in various industries. Its chemical formula is Al2(SO4)3, indicating that it consists of two aluminum (Al3+) ions combined with three sulfate (SO42-) ions. This compound usually exists as a white crystalline solid and is typically found in its hydrated form, such as Al2(SO4)3·18H2O, where water molecules are integrated into its crystal structure. In terms of solubility, aluminum sulphate is highly soluble in water. When dissolved, it dissociates into aluminum and sulfate ions, which makes it useful in a variety of applications that rely on these ions. The solubility of aluminum sulphate increases with temperature, enabling it to readily dissolve in warm water to form clear solutions. However, it is practically insoluble in alcohol and other organic solvents.
Uses in chemical industries
Before understanding qualitative Inorganic Analysis of Aluminum Sulphate, Let’s understand uses in chemical industries, Aluminum sulphate is a widely utilized chemical compound in various industries due to its versatile properties. In the chemical industry, one of its primary uses is as a coagulating agent in water treatment processes. When added to water, aluminum sulphate reacts to form aluminum hydroxide flocs that help to trap and remove impurities, making water safer for consumption and industrial use. Additionally, it serves as a key ingredient in the paper manufacturing industry, where it is used to improve the sizing and quality of paper by helping to bind the fibers more effectively. Aluminum sulphate is also employed in the dyeing and tanning industries; it acts as a mordant to fix dyes on fabrics and assists in leather processing by stabilizing the tanning agents. Its role extends to the production of baking powders and antiperspirants, where its chemical properties aid in the desired reactions. Overall, aluminum sulphate is an essential compound that supports a wide range of chemical industry applications thanks to its effective coagulating, binding, and stabilizing capabilities.
Qualitative Inorganic Analysis of Aluminum Sulphate
Analysis of Acidic Radicals (Anions)
| Test | Observation | Inference |
|---|
Preliminary Test
| Color | Colorless | Salts of Cu2+, Ni2+, Co3+, CrO4 2- , Fe3+ etc. may be absent |
| Odor | No specific odor | Ammonium ions & Acetate ions may be absent |
Dry Test
| Dilute Sulphuric acid test: Take 0.5 gm of Salt and then add Dilute H2SO4 | No Effervescence of CO2 | CO3 2- ions absent |
| Concentrated Sulphuric Acid Test: Take 0.5 gm of salt and then add Concentrated H2SO4 dropwise from the side of the test tube | No gas evolved | Chloride, Bromide, Iodide, Nitrate and Acetate ions absent |
| Barium Chloride test: Take 0.2 gm of salt and add Aqueous Barium Chloride solution | White precipitates are observed | Sulphate ions are present. |
Confirmative test for Sulphate ions
| Barium Chloride Test: Take 0.2 gm of Salt, add Barium chloride solution. | White precipitates are formed, which are insoluble in dilute HCl | Sulphate ions Confirmed |
| Lead Acetate Test: Take 0.5 gm of salt, add aqueous Lead Acetate solution. | White Precipitates are formed | Sulphate ions Confirmed |
Thus, the acidic radical is Sulphate ions (SO42-)
Test for Basic Radicals
| Solubility in water: Take 2.0 gm of salt and add water | Clear solution formed This is referred as original Solution (O.S.) | Water soluble salt. |
| O.S. + Dilute NaOH: Take 5 ml of O.S. and add Dilute NaOH solution if required heat gently | No Ammoniacal odor | Group Zero absent NH4 1+ ions absent |
| O.S. + Dilute HCl: Take 5 ml of O.S. and add dilute HCl solution | No white Precipitates | First group absent Lead (II) ions absent |
| O.S. + Dilute HCl + H2S gas Take 5 ml of O. S. add dilute HCl and then pass H2S into the solution in test tube | No Black Precipitates | Second group absent Lead (II), Copper (II) Mercury (II) ions absent |
| O.S. + Ammonium Chloride (solid) + Aqueous Ammonium Hydroxide Take O.S. and add NH4Cl(s) + NH4OH(aq) | Gelatinous white precipitates | Third Group present Aluminum ions present. |
Confirmative Test for Aluminum (III) ions
| Lake Test: O.S. + two drops of dilute HCl (shake well) then add 2 drops of blue litmus solution followed with NH4 OH (aq) Solution drop wise | Blur precipitates floating on colorless solution | Al+3 (Aluminum (III)) ions Confirmed |
| Cobalt Nitrate Test: Add salt +cobalt nitrate in charcoal cavity test | Blue mass in charcoal cavity | Al+3 (Aluminum (III)) ions Confirmed |
Thus, Basic radicals are Al+3 (Aluminum (III)) ionsÂ
The given inorganic Salt is (Al2(SO4)3 Aluminum sulphate)Â
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