Why can water be separated from inky water by simple distillation?
A. Ink does not mix with water.
B. Ink evaporates, leaving the water behind.
C. Water and inks have different boiling points.
D. Water evaporates, leaving the ink particles behind.
The correct answer and explanation is:
Correct Answer: C. Water and inks have different boiling points.
Simple distillation is a method used to separate a solvent from a solution based on differences in boiling points. In the case of inky water, the mixture consists of water as the solvent and ink as the solute. The key reason water can be separated from this mixture through simple distillation lies in the fact that water and ink components have different boiling points.
Water boils at 100°C at standard atmospheric pressure. Ink, on the other hand, contains dyes, pigments, and other compounds that do not evaporate at this temperature. When the inky water mixture is heated during distillation, the water turns into steam (vapor) at its boiling point. The ink particles, which have much higher boiling points or may not evaporate at all, remain in the distillation flask.
The water vapor then passes through a condenser where it cools and changes back into liquid water. This distilled water is collected separately in a receiving container. The remaining ink, which could not evaporate, stays behind in the boiling flask.
Simple distillation works effectively only when the components of a mixture have significantly different boiling points. In the case of inky water, the components of ink do not vaporize with water and hence are left behind. This difference in boiling points makes it possible to obtain pure water from the solution.
This technique is commonly used in laboratories and industries to purify water or recover solvents. It is important to note that if ink were made from volatile substances (which evaporate easily), then simple distillation might not be effective, and fractional distillation or another method would be required. But in this case, the simple method is sufficient due to the large difference in boiling points.