Grant Fluga
5 Oct. 1998
6th Hour


The purpose of this experiment was to observe crystals form. To compare crystal shapes formed from different substances. To compare crystal shapes from same substance formed during different lengths of time. Last of all to determine if crystal shapes change when substances are mixed.


In this lab the equipment used was as follows. Equipment consisted of a Monocular Microscope, Hot Plate, Chemical Forceps, Microscope Slides, Safety Glasses, Plain White Paper, Pencil, and different kinds of crystals.


Crystals from an evaporate:

1. Place 3-4 drops of salt (NaCl) solution on a microscope slide.

Do not use a cover slip (you want it to evaporate) .

Set the slide on a piece of paper with your name on it and place it
on top of one of the cabinets.
Allow it to evaporate overnight and observe it tomorrow.

Observe the crystals formed on the slide using the monocular
microscope at high power.

Draw the shape of the crystal, measure the average crystal size
and make any written observations necessary.

Compare the salt (NaCl) crystal that grew naturally to the ones
you observed growing in lab.

2. Repeat #1 using a comparable amount of alum solution.

3. Mix and Match

Mix 2 drops of salt solution with 2 drops of alum solution.
Repeat #1

Crystals from a melt:

4. Place ~1 flake (~1 g) of paradichlorobenzene (moth crystal)
microscope slide.

Heat the microscope slide by holding it with chemical forceps just
above the surface of a hot plate until the crystal melts.
(note: if you set the slide directly on the surface of the hot
plate, it will shatter- - wear safety glasses during the time
you are melting the crystals on the hot plate.

Transfer the slide to the microscope stage, but DO NOT place the
slide directly on the stage. Cover the stage first with
either white or black paper. Observe the crystals

Draw the shape of the crystal, measure the average crystal size
and make any written observations necessary.

Compare the paradichlorobenzene crystals that grew for years in
The large stock jar to the ones you observed growing.

5. Repeat #4 using a comparable amount of sulfur.

6. Mix and Match. Repeat Step #4, but this time, put both sulfur
and paradichlorobenzene crystals together on the slide.



We watched crystals grow from two different sets of conditions. Those conditions were melted, and evaporated. The shapes of the crystals formed from both the sulfur and paradichlorobenzene were different. The shapes formed by the table salt and alum formed from an evaporate were also different. The crystal shapes in this lab were all prism shapes. The factor that must determine crystal shape is the way they come together. The thing I liked most about this lab is that the crystals looked really cool.

Applying to nature

I was in the Mammoth Caves once and saw lots of shiny looking things but couldn’t figure out what they were called and why they were there. This lab helped me figure this out.