A sample of naphthalene, which should be pure white, was found to have a grayish color after the usual purification procedure. The melting point was correct, and the
melting point range was small. Explain the gray color.
The first explanation is impossible, since any purity would change the melting point, even if the impurity has the same melting point as naphthalene.
If the procedure involves the removal of colored impurities via charcoal, then it is likely that the color is caused by residual charcoal. Keep in mind, charcoal doesn't form a solution with naphthalene, so the melting point wouldn't be affected, even with the charcoal present as an impurity.
The gray color of the naphthalene sample could be due to the presence of impurities in the substance. Even though the melting point was correct and the melting point range was small, impurities can still affect the color of the substance.
Naphthalene is typically a pure white crystalline solid. However, impurities such as dust, dirt, or other organic compounds can introduce color to the substance, leading to a grayish appearance. These impurities may be introduced during the purification procedure or present in the original source material.
It is possible that the purification procedure used was not completely effective in removing all impurities, resulting in the gray color. However, since the melting point was correct and the melting point range was small, it suggests that the main component of the sample is still naphthalene.
To obtain a pure white color, further purification techniques such as recrystallization or sublimation may be needed to remove the remaining impurities.
The gray color observed in the sample of naphthalene after the purification procedure could be attributed to impurities present in the compound. When naphthalene undergoes purification, it is typically accomplished through processes like recrystallization or sublimation.
During these processes, impurities in the naphthalene may not be completely removed, leading to a grayish color in the final product. This grayish color indicates the presence of impurities that may have been dissolved or trapped within the crystal lattice of the naphthalene.
The impurities can come from various sources, such as manufacturing residues, other compounds that are not removed during the purification process, or even oxidation products formed during storage or exposure to air. These impurities can introduce a slight color change to the otherwise pure white naphthalene.
It is important to note that despite the gray color, the melting point of the naphthalene sample remains correct, and the melting point range is small. This indicates that the impurities present in the sample do not significantly impact the overall purity of the naphthalene, as they do not affect its melting behavior.
To obtain a purer white naphthalene, further purification methods, such as repeated recrystallization, may be employed to enhance the removal of impurities. Additionally, storing the purified naphthalene in a sealed container, protected from light and air, can help maintain its white color and prevent the formation of additional impurities.