Physical and Inorganic Chemistry Lab 2 PDF

Physical and inorganic chemistry Section 2 PMC (101) [email protected] Qualitative determination of Anions Acid + base →Salt + water Na Cl HCl + NaOH → NaCl + H2O Na+ Cl-...

Physical and inorganic chemistry Section 2 PMC (101) [email protected] Qualitative determination of Anions Acid + base →Salt + water Na Cl HCl + NaOH → NaCl + H2O Na+ Cl- Cation Anion Cation: is positive charged fragment of salt Anion: is negative charged fragment of salt The scheme of classification of anions depend on: 1-Dry reactions: Identification of volatile product when salts are treated with acid (dil HCl, dil H2SO4) Ex: HCl and H2SO4 displace carbonic acid. It divided into: A- Involving volatile product upon treatment with dil. acid. B- Involving gases with conc. H2SO4. 2-Wet reactions: Colour, precipitation, oxidation reduction reactions. 3-Specific and selective reactions for each anions:  Identification of carbonate group Carbonate (CO32-) & Bicarbonate (HCO3-)  I. Carbonate group This group includes carbonate CO32- and bicarbonate HCO3-. These are the salts of carbonic acid. The anion are represented as: 1. Carbonate ion: CO32- 2. Bicarbonate ion: HCO3- The first step of carbonic acid ionization produces bicarbonate ion , and the second step results in the formation of carbonate ion H2CO3 HCO3- + H+ CO32- + H+ Tests of carbonate and bicarbonate  Dry reactions: 1-Action of dil. HCl A- In Carbonate: Effervescence due to evolution of colorless, odorless CO2 gas. This gas turns lime water Ca(OH)2 turbid due to precipitation of CaCO3 B- In Bicarbonate: The same as CO32-   Wet reactions: 2-BaCl2 test A- In Carbonate: Immediate white ppt of BaCO3 soluble in dil. HCl. B- In Bicarbonate: White ppt of BaCO3 after boiling. Wet reactions: 3-MgSO4 test A- In Carbonate: Immediate white ppt of MgCO3. 𝑁𝑁𝑁𝑁2 𝐶𝐶𝐶𝐶3 + 𝑀𝑀𝑀𝑀𝑆𝑆𝑆𝑆4 ⎯⎯⎯ 𝑀𝑀𝑀𝑀𝐶𝐶𝐶𝐶3 + 𝑁𝑁𝑁𝑁2 𝑆𝑆𝑆𝑆4 B- In Bicarbonate: White ppt of MgCO3 after boiling.  Wet reactions: 4- HgCl2 test A- In Carbonate: Reddish brown ppt of basic mercury carbonate (Hg4O3.CO3). B- In Bicarbonate: *No observation Identification of carbonates & bicarbonates CO32- HCO3- Soluble in dil. HCl  Test Observation Comment Effervescence due to evolution of Action of Maybe CO32- colorless, odorless CO2 gas. Dil. HCl Immediate white ppt. of BaCO3 soluble BaCl2 test Maybe CO32- in dil. HCl. Conclusion: ………………………………………………………. Sample is CO (Carbonate) 2- 3 Thank You gu.edu.eg