The solubility of a compound is 59g per 100mL in boiling methanol and 30g per 100mL in cold methanol, whereas its solubility in water is 7.2g per at 95 degrees Celsius and 0.22g per 100mL at 2 degrees Celsius. Which solvent would be better for recrystallization of the compound? Explain.
I would use H2O as the solvent because the methanol dissolves 30 g/100 mL whereas you lose only 0.22 g/100 in water.
i will go for methanol
To determine which solvent would be better for recrystallization of the compound, we need to consider the solubility characteristics of the compound in each solvent at the desired temperature.
In this case, we have two solvents: methanol and water. Let's compare the solubilities of the compound in each solvent at their respective temperatures:
1. Methanol:
- Solubility in boiling methanol: 59g/100mL
- Solubility in cold methanol: 30g/100mL
2. Water:
- Solubility at 95 degrees Celsius: 7.2g/100mL
- Solubility at 2 degrees Celsius: 0.22g/100mL
Solubility is usually higher at higher temperatures, and recrystallization typically involves dissolving the compound in a hot solvent, followed by slow cooling to promote crystal formation.
Considering these solubility values, it is evident that the compound has a significantly higher solubility in methanol compared to water. Both boiling and cold methanol have higher solubilities for the compound (59g and 30g/100mL, respectively) compared to the solubilities in water (7.2g and 0.22g/100mL at 95 and 2 degrees Celsius, respectively).
Therefore, methanol would be the better solvent choice for recrystallization of the compound, as it offers a higher solubility and would allow for more effective dissolution and subsequent cooling for crystal formation.
To determine which solvent would be better for recrystallization of the compound, we need to consider the solubilities of the given compound in both methanol and water, at different temperatures.
In recrystallization, the goal is to dissolve the compound in a solvent at a high temperature and then have it crystallize out of the solution upon cooling. The ideal solvent should have a significant difference in solubility between its high-temperature and low-temperature states, allowing for efficient crystallization.
Let's compare the solubilities of the compound in methanol and water:
1. Methanol:
- Solubility in boiling methanol: 59g per 100mL.
- Solubility in cold methanol: 30g per 100mL.
2. Water:
- Solubility at 95 degrees Celsius: 7.2g per 100mL.
- Solubility at 2 degrees Celsius: 0.22g per 100mL.
From the given information, we can observe that the solubility of the compound in methanol has a relatively smaller difference between boiling (59g) and cold (30g) temperatures. This indicates that the compound does not significantly precipitate or crystallize out upon cooling. Methanol may not be the best solvent for efficient recrystallization.
On the other hand, the solubility of the compound in water shows a substantial difference between higher (7.2g) and lower (0.22g) temperatures. The compound has a higher solubility at higher temperatures but significantly lower solubility at lower temperatures. This suggests that water could be a promising solvent for recrystallization, as the compound is more likely to crystallize out upon cooling due to the significant change in solubility.
Therefore, based on the solubility data provided, water would be a better solvent for the recrystallization of the compound compared to methanol.