Suggest reasons why recrystalization from water would probably not be a suitable procedure for purifying the following substances:
sodium chloride
Calcium carbonate
ethanol
NaCl--too soluble
CaCO3--not soluble enough
ethanol--miscible with water in all proportions.
Sodium chloride:
- Recrystallization from water would not be suitable for purifying sodium chloride because it is highly soluble in water. The solubility of sodium chloride in water is very high, meaning that it would be difficult to separate it from impurities using this method.
Calcium carbonate:
- Recrystallization from water would not be suitable for purifying calcium carbonate because it is insoluble in water. Calcium carbonate has a low solubility in water, which means that it will not readily dissolve for the recrystallization process. This would make it challenging to separate impurities from the calcium carbonate using water as the solvent.
Ethanol:
- Recrystallization from water would not be suitable for purifying ethanol for two main reasons. Firstly, ethanol is highly soluble in water, which means that it would be difficult to selectively crystallize and separate the ethanol from impurities. Secondly, water can form an azeotrope with ethanol, which means that the two substances can form a constant boiling mixture, making it challenging to separate them by simple crystallization.
To determine why recrystallization from water might not be a suitable purification method for sodium chloride, calcium carbonate, and ethanol, we need to consider the solubility properties and other characteristics of these substances.
1. Sodium Chloride:
Recrystallization from water is likely not suitable for purifying sodium chloride because it is extremely soluble in water. Sodium chloride has a high solubility, meaning that even at room temperature, a significant amount of sodium chloride would remain dissolved in water rather than precipitating out as pure crystals. Additionally, sodium chloride has a simple crystal structure, which makes impurity removal challenging using recrystallization techniques.
2. Calcium Carbonate:
Recrystallization from water is also not appropriate for purifying calcium carbonate. Although calcium carbonate is less soluble in water compared to sodium chloride, it still has appreciable solubility. This means that during recrystallization, significant amounts of impurities might co-precipitate with the calcium carbonate, leading to a contaminated final product. Furthermore, calcium carbonate can undergo decomposition or phase changes at high temperatures, making recrystallization conditions difficult to control.
3. Ethanol:
Recrystallization from water is generally unsuitable for purifying ethanol due to their significant miscibility (ability to mix) with each other. Ethanol and water form an azeotropic mixture, meaning they form a constant boiling point mixture, making it challenging to separate them by simple recrystallization. Traditional recrystallization methods rely on the solubility differences between the substance and the solvent, which is not the case for ethanol and water.
Overall, other purification techniques such as distillation, chromatography, or extraction are generally better suited for purifying substances like sodium chloride, calcium carbonate, and ethanol, rather than recrystallization from water.