Whats Going On?
Why does the string need to be soaked
and then dried?
string will provide the surface on which the crystals will
grow. As water evaporates from the string, small crystals
of sugar will encrust the string. These tiny seed crystals
provide starting points for larger crystals. Future growth
will be concentrated around these points.
What makes the crystals grow?
different methods will contribute to the growth of the crystals
on the string. You have created a supersaturated solution
by first heating a saturated sugar solution (a solution
in which no more sugar can dissolve at a particular temperature)
and then allowing it to cool. A supersaturated solution is
unstableit contains more solute (in this case,
sugar) than can stay in a liquid formso the sugar will
come out of solution, forming what's called a precipitate.
This method is called precipitation.
other is evaporationas time passes, the water
will evaporate slowly from the solution. As the water evaporates,
the solution becomes more saturated and sugar molecules will
continue to come out of the solution and collect on the seed
crystals on the string. The rock candy crystals grow molecule
by molecule. Your finished rock candy will be made up of about
a quadrillion (1,000,000,000,000,000) molecules attached to