During the preparation of K3[Al(C2O4)3].3H2O, NaOH was added slowly and with stirring over an approximately 10-minute period to a solution of Al2(SO4)3 solution. The combined solution was heated to almost boiling and left to stand for a few minutes.
1. Why does NaOH added slowly with stirring over a 10-minute period?
2. Why was the combined solution heated and left to stand for a few minutes?
You haven't written all of your procedure for the oxalate hasn't been added at this time. One reason NaOH is added slowly is to prevent the pptn of Al(OH)3.
1. NaOH is added slowly with stirring over a 10-minute period to ensure proper mixing and reaction between NaOH and Al2(SO4)3 solution. By adding NaOH slowly, it allows for a controlled reaction and prevents sudden pH changes, which could lead to inappropriate precipitation or other unwanted side reactions. Stirring ensures uniform mixing and enables the reactants to come into contact with each other effectively.
To achieve this, you would need to set up the experiment by first measuring the appropriate amounts of NaOH and Al2(SO4)3 solution. Then, slowly add NaOH to the Al2(SO4)3 solution while stirring continuously for about 10 minutes. It is important to keep a consistent stirring speed and ensure that NaOH is added gradually rather than all at once.
2. The combined solution is heated to almost boiling and left to stand for a few minutes to promote the formation of the desired compound K3[Al(C2O4)3].3H2O and to facilitate any necessary reactions or changes in the solution.
Heating the solution to almost boiling provides the energy needed for the reaction to occur at a faster rate. This is important for ensuring that the reaction proceeds to completion and that the desired compound is formed.
After heating, leaving the solution to stand for a few minutes allows for any precipitates or solid materials to settle down. This process is called gravity filtration, where denser solids will settle to the bottom of the container. By allowing the mixture to settle, you can then easily separate the clear supernatant liquid from any solid impurities.
Overall, both the heating and standing steps are crucial for obtaining a pure product with improved purity and clarity.