Preparation of Mohr's salt and Alum: Mohr's salt (Na2CrO4) is a salt that contains sodium, chromium(VI), and oxygen ions. It is prepared by the reaction of sodi...
Preparation of Mohr's salt and Alum:
Mohr's salt (Na2CrO4) is a salt that contains sodium, chromium(VI), and oxygen ions. It is prepared by the reaction of sodium hydroxide (NaOH) and nitric acid (HNO3). The balanced chemical equation for this reaction is:
2NaOH + 2HNO3 -> Na2CrO4 + 2H2O + NaOH
The sodium ions (Na+) from the NaOH react with the nitrate ions (NO3-) from the HNO3 to form sodium nitrate (NaNO3). The chromium(VI) ions (CrO42-) from the Na2CrO4 react with the hydroxide ions (OH-) from the NaOH to form chromium(VI) hydroxide (Cr(OH)6). The oxygen ions (O2-) from the HNO3 react with the hydroxide ions to form water (H2O).
Once the reaction is complete, the sodium salt (Na2CrO4) is filtered out, dried, and washed with water. The chromium(VI) hydroxide is insoluble in water, so it precipitates out of the solution.
Mohr's salt is used in various chemical analyses, such as the determination of chromium in ores and alloys. It is also used as an indicator in redox reactions