Sponsored by the
CHEMICAL INSTITUTE OF CANADA'S
NATIONAL CHEMISTRY WEEK
Here you will learn how this year's contest was conducted.
PAST RESULTS
Sections will be encouraged to make three submissions:
Best Overall,
Best Quality, and
Best Teacher's.
STEP ONE - REGISTER
This contest is open to any high school student or teacher in Canada
Contact your Local Area Coordinator to let him/her know that you are participating.
If you are unsure of who your coordinator is, contact The Wizard
(also known as Dr. Chris Young) at:
E-mail youngjc@em.agr.ca or
Phone 519 829-2400 x3114 or
FAX 519 829-2600 or
Backup E-mail thewiz@sentex.net
If you do not "fit" into one of the established Local Areas, contact The Wizard and you will be placed in the "Outliers" group. The deadline for submission of your crystals will be October 31, 2001.
STEP TWO - GET YOUR STARTING MATERIAL
This year we will be using aluminum potassium sulfate (also known as Alum) kindly donated by Anachemia Science.
To order your material, call Anachemia directly at 1-800-361-0209 and ask for Part Number 0391 - 500g PROMO. They will ship 500 g of Alum directly to you FOR FREE!
NOTE: Only teachers may order material, which must be shipped directly to a school.
If you need more material (for possible reason, see below) order it at the same time. This year, there will be NO charge for an extra bottle or two.
STEP THREE - PREPARE YOUR CRYSTAL(s)
You are free to use any procedure you like to prepare crystals. For your convenience, suggested seed crystal growing procedures followed by detailed instructions are provided here.
Also included is background information and links to other web sites on crystals and general approaches to growing crystals.
However there is no limit to the number of students asssigned to a team, nor is there a limit to the number of teams permitted at a given school.
(a) [Handbook of Chemistry and Physics, 45th Ed (1964-5)]
About 10 g in 100 mL water is about pH 3
(b) [Merck Index, 10th Ed (1983)]
STEP 4 - HAVE YOUR CRYSTAL(s) JUDGED
Make arrangements with your Local Coordinator for your best crystal(s) to be judged.
Each school is encouraged to submit two crystals to the Local Coordinator; one for best quality and one for best overall. It is recognized that where several crystals from a school may be of roughly equivalent over-all quality, and it is difficult to make a choice, it may be necessary to submit several crystals. Of these several crystals from a particular school, only one may be the "official" crystal to be considered for all prize(s) awarded locally.
Nominally, we would like to have the crystals judged early in National Chemistry Week (October 14-20, 2001), so that the winners can be displayed later in the week.
However, there may be unforseen delays in getting starting material to schools. Then, at the discretion of the Local Coordinator, judging may have to take place at a later time.
In November, the best crystal from each Local Area will be sent for judging at the National Level. A Trophy and cash prizes are given to the students preparing the best crystals.
JUDGING CRITERIA
The idea is to grow a SINGLE CRYSTAL, not a bunch of crystals. It is therefore essential to avoid excessive rapid growth, which encourages the formation of multiple crystals, not a single crystal.
One single crystal will be judged only on the basis of quality as outlined below.
The other single crystal will be judged on the basis of combining mass and quality factors as outlined below.
The quality is judged by experts who will rank the crystals on a scale of 0-10. A score of 10 will be given to a perfect gem quality crystal which fits the ideal crystal structure known for the chemical.
1. The crystal is weighed, and the mass M recorded.
2. The quality of the crystal is judged on a scale of 1 to 10, with 10 representing a perfect crystal. The following factors will be considered in judging quality:
Total Quality Q = x.xx (out of 10)
3. The total score is then determined as follows:
Total Score = [log (M+1)] x Q x 10
The logarithm of the mass is chosen so that large poor quality crystals don't swamp out smaller good quality crystals.
The crystal with the highest score is the winning crystal.
This score is nearly an absolute score that could be used to judge different types of crystals. The term "nearly" must be added, since the absolute score will depend upon how much starting material was used. For example:
In the 1998 NCW Contest the maximum mass would have been 201 g. A crystal that heavy that scores a perfect 10 on quality would get
The best crystal that year scored
In one other contest we know about, the maximum allowable amount of starting material is 500 g. A perfect crystal from there would get
In this example, the smaller crystal would get a slightly higher score.
NEED MORE STARTING MATERIAL?
Obviously, the 500 g of starting material supplied will be insufficient where there are more than three teams at a school. If a school wishes greater participation, then the school will have to obtain more material.
This can be done by requesting extra from Anachemia at the time of ordering.
a) match/mismatch with crystal type (out of 2)
b) presence/absence of occlusions (out of 2)
c) intact/broken edges (out of 2)
d) well formed/misformed faces (out of 2)
e) clarity/muddiness (out of 2)
The value 1 is added to the mass so that crystals weighing less than 1 g get a positive score.
[log (201+1)] x 10 x 10 = 230
the highest possible score.
[log (57+1)] x 9.80 x 10 = 172.8
or 85.1 % of theoretical maximum.
[log (500 +1)] x 10 x 10 = 270
and a 250 g crystal scoring 9.5 would get
[log (250 + 1)] x 9.5 x 10 = 228
or 84.4% of maximum.
You will note that as the crystals get bigger, unless you pay very close atttention to details, the quality of the crystal may decrease (e.g. become milky as is illustrated here).
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