Again, from my previous question about gravimetric analysis...
Why can't NH4Cl be used as a substitute for NH3 in precipitating MgNH4PO4*6H2O?
Please critique my thought:
I found out that a precipitate is more soluble at lower pH and since NH4Cl acidic, it will cause the precipitate to revert to its dispersed state and may cause loss of analyte. Am I right?
Yes.
thanks a lot :D
You're welcome!
You're welcome! I'm glad I could help. If you have any more questions, feel free to ask.
You're welcome! I'm glad I could help. And you are correct in your reasoning.
In gravimetric analysis, NH4Cl cannot be used as a substitute for NH3 in precipitating MgNH4PO4*6H2O, and your thought process is on the right track.
The reason for this is that NH4Cl is acidic in nature, meaning it will release H+ ions when dissolved in water. This increase in acidity can disrupt the precipitation process and cause the precipitate to revert back to its dispersed state. In the case of MgNH4PO4*6H2O, the pH plays a crucial role in the precipitation reaction. At higher pH levels, the formation of the desired precipitate is favored.
By using NH3, which is a weak base, the pH of the solution increases, favoring the formation of the precipitate. NH3 accepts H+ ions and increases the pH, maintaining a basic environment necessary for the precipitation of MgNH4PO4*6H2O.
Using NH4Cl instead of NH3 can lead to a loss of analyte as the desired precipitate may not form properly. It is important to carefully select reagents and understand their effects on the reaction conditions to obtain accurate and reliable results in gravimetric analysis.