1. Low solubility: Lead hydroxide is insoluble in water. This means that only a very small amount of lead hydroxide will dissolve in the solution, limiting the concentration of hydroxide ions (OH-) available to react with ammonium salts. This makes the reaction slow and inefficient.
2. Formation of lead salts: Lead hydroxide reacts with ammonium salts to form lead salts, which are insoluble and precipitate out of the solution. This effectively removes lead hydroxide from the reaction mixture, further hindering the production of ammonia.
3. Toxicity: Lead compounds are toxic. Using lead hydroxide in the preparation of ammonia introduces the risk of lead contamination in the final product, which is undesirable.
4. Alternative alkalis: There are more suitable and readily available alkalis for the preparation of ammonia, such as sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2). These alkalis are highly soluble in water, react efficiently with ammonium salts, and do not pose the same toxicity concerns as lead hydroxide.
In summary, using lead hydroxide for ammonia preparation is inefficient, leads to unwanted side reactions, and introduces toxicity concerns. Therefore, it is not preferred in favor of other readily available and more suitable alkalis.
