• Fill half a beaker with water.
• Put a watch glass on the mouth of the beaker (Fig. 2.5).
• Put few drops of ink on the watch glass.
• Now start heating the beaker. We do not want to heat the ink directly. You will see that evaporation is taking place
from the watch glass.
• Continue heating as the evaporation goes on and stop heating when you do not see any further change on the
• Observe carefully and record your observations.
• What do you think has got evaporated from the watch glass?
• Is there a residue on the watch glass?
• What is your interpretation? Is ink a single substance (pure) or is it a mixture?
We find that ink is a mixture of a dye in water. Thus, we can separate the volatile component (solvent) from its non-volatile solute by the method of evaporation.