How Do You Calculate and Test the Properties of Hydrated Alum?

[gunnar]

Hi. I got some questions I need to answer. Just to make sure I'm correct I would appreciate if someone could comment on my answers.

1. Q. When calculating the theoretical yield of an alum that has water molecules attached to the double salt. Are these included in the calculation?
A. I should include the water molecules.

2.Q. Why does is produce a more reliable yield to let an alum solution cool in a refrigerator.
A. The reaction goes more slowly.

3.Q.How can I test the alum for waters of hydration?
A. By subtracting the water molecules

4. Q.Why is the melting point of an alum lower than the actual melting point?
A. Not pure enough.

 

[QuantumMech]

Your answers are correct but I am not sure about #3.

 

[thepatientmental]

1. Comment: Yes, you are correct. Water molecules should be included in the calculation as they are a part of the compound and contribute to the overall yield.

2. Comment: Good job, you are correct. Allowing the reaction to cool slowly in a refrigerator helps to slow down the reaction and produce a more reliable yield.

3. Comment: To test for waters of hydration, you can heat the alum and observe any changes in mass. The loss of mass would indicate the loss of water molecules.

4. Comment: Your answer is partially correct. The impurities in the alum can also contribute to a lower melting point. To achieve the actual melting point, the alum must be pure.