if calculating molecular weight of unknown by freezing point depression...All of the unknowns in the activity were nonpolar organic molecules with molecular weight= 100-250 g/mol and using around 1g of the unknown. Provide an example of a solvent that could possibly be used for this experiment and provide reasons why it would be a good choice. Provide a solvent that should not be used for this experiment and provide reasons why it would not be a great choice. Other than using around 7g of benzophenone.

What is "other than 7g benzophenone" mean?

1. Compare the freezing point constants, Kf, for the solvents.
2. How accurately can you read the thermometer.
I would use those two things and calculate about how much of the solvent and how much of the unknown would be needed to read the temperature with reasonable accuracy using about 175 for the molar mass.

To calculate the molecular weight of an unknown compound using freezing point depression, you need to use a suitable solvent. Let's discuss an example of a solvent that could potentially be used for this experiment, along with reasons why it would be a good choice, and another solvent that should not be used and the reasons why it would not be ideal.

Example solvent: Hexane (C6H14)
Reasons why it would be a good choice:
1. Hexane is a nonpolar solvent, which makes it compatible with nonpolar organic compounds typically found in the given range of molecular weight (100-250 g/mol).
2. Hexane has a low freezing point (-95 °C), ensuring sufficient depression of the freezing point of the solution when mixed with the unknown compound.
3. Hexane is relatively inexpensive and readily available, making it practical for this experiment.

Solvent to avoid: Water (H2O)
Reasons why it would not be a great choice:
1. Water is a polar solvent, which may not efficiently dissolve nonpolar organic molecules. Therefore, it may not provide accurate results for determining the molecular weight of the unknown compound.
2. The freezing point of water is 0 °C, which is relatively close to room temperature. Consequently, the depression in freezing point may be insufficient, leading to inaccurate calculations.
3. Water is a common and easily accessible solvent, but it is not suitable for this experiment due to its polarity and freezing point characteristics.

It's worth noting that while benzophenone is mentioned in the question as an example, it is not a solvent but an example of a solute (unknown compound) used in the experiment. Therefore, we focused on discussing suitable and unsuitable solvents for the freezing point depression method.