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Re: Crime Busters B: PETE v. PVC
Posted: December 7th, 2015, 12:37 pm
by sciolylover13
christseeker wrote:I got the following info from the internet, is this true? My pellets sure don't match what is described.
"What do these pellets feel like?
P.E. pellets feel like half of a sphere, and P.V.C. pellets are smaller than P.E. pellets, they feel cylinder but round on one side."
The shape and size of your pellets will vary with different distributors. You probably got your pellets from a different distributor than the source online.
Crime Buster
Posted: January 10th, 2016, 4:07 pm
by Ccde123456789
I was wondering if you are allowed to use a table in your analysis.
Please respond.
Thanks
Re: Crime Busters B
Posted: January 10th, 2016, 6:04 pm
by samlan16
Moving this question to the right forum:
Ccde123456789 wrote:I was wondering if you are allowed to use a table in your analysis.
Please respond.
Thanks
No, they specifically want an essay or short answer responses if given in that format. However, you may use a table to formulate your conclusion.
Re: Crime Busters B
Posted: February 9th, 2016, 11:31 am
by megan_scioly
I was wondering if there was a good way to tell the difference between mixtures of powders. If anyone has any links or techniques, do tell. Thanks!
Re: Crime Busters B
Posted: February 9th, 2016, 11:47 am
by samlan16
megan_scioly wrote:I was wondering if there was a good way to tell the difference between mixtures of powders. If anyone has any links or techniques, do tell. Thanks!
Here is a post of mine from last season about this. I should probably put this on the wiki.
First of all, there are 3 nonmetals which can never be mixed in this event: yeast, vitamin C, and sodium acetate. That being said, everything left is neutral or basic and non-biological.
The key to finding the components to a mixture is to react each off individually. If there appears to be a powder and a crystalline component, add HCl or iodine to a sample. If the iodine turns blue, finding the first component will be straightforward because you will only need to find the pH of the mixture with water. A more neutral pH will mean that it's flour; a more basic pH will mean cornstarch. If the iodine fizzes (and the HCl), then you have Alka-Seltzer. A fizz with only the HCl means the component is either CaCO3 or NaHCO3. Once again, a pH test will show the difference: a neutral pH means calcium carbonate, and a basic pH means baking soda. No reaction means gypsum. To find the crystal, test for solubility. Sand will not dissolve, whereas salt and sugar will. The difference between the latter two is that salt has cubic crystals, and sugar has irregular crystals.
Two crystals is fairly easy because you can skip the HCl and iodine and go straight for solubility. Once again, a component that does not dissolve is sand, and a component that does is either salt or sugar, which can be differentiated by crystal shape. If both dissolve, you have salt and sugar (probably the single most common mixture in this event).
For two powders, test with iodine first, then HCl if not all of the mixture fizzed or turned blue, and finally pH if needed. Go off of the information above to find each, and use logic if two things react at once.
Hope this helps!
Crime Busters B
Posted: February 16th, 2016, 5:53 pm
by yashicak
How are we supposed to differentiate the types of fibers during a test? Will we be allowed to use a microscope or just be given samples?
Re: Crime Busters B
Posted: February 18th, 2016, 6:57 pm
by samlan16
yashicak wrote:How are we supposed to differentiate the types of fibers during a test? Will we be allowed to use a microscope or just be given samples?
Most of the time, you will be given a microscope, but some regional tournaments may not give you one. They should also give you a candle for burn tests.
To differentiate the types of fibers, you will really only need the burn test results. Hold the fiber near, but not in, the flame and observe what happens. A fiber that quickly melts and/or smokes and leaves a plastic residue is a synthetic fiber. (Note that synthetic fibers are plastic, so the residue itself is plastic!) If the fiber burns or warps, and the smoke smells like burning hair, the type is animal. If the fiber burns and emits smoke that smells kind of like celery (it's really hard to describe), the fiber is plant-based.
That being said, I remember all of the above with this: animals have hair, celery is a type of plant, and plastic is synthetic.
Hope this helps!
Re: Crime Busters B
Posted: March 18th, 2016, 7:17 pm
by PrincessRibbons
Will I have to bring my own HCI, Iodine, pH paper, distilled water, and chromatography materials to the competition?
Re: Crime Busters B
Posted: March 19th, 2016, 6:39 am
by Panda Weasley
PrincessRibbons wrote:Will I have to bring my own HCI, Iodine, pH paper, distilled water, and chromatography materials to the competition?
You will be provided with HCl and iodine, but you'll need to bring pH paper and chromatography materials. You probably won't need to bring beakers for chromo, but I would double check your rules/tournament info. As for distilled water I am not sure. The rules regarding whether or not to bring it seems to change every year and I don't have a current copy of the rules. Hopefully someone else will be able to better answer your question.
Re: Crime Busters B
Posted: March 22nd, 2016, 6:57 pm
by PrincessRibbons
Panda Weasley wrote:PrincessRibbons wrote:Will I have to bring my own HCI, Iodine, pH paper, distilled water, and chromatography materials to the competition?
You will be provided with HCl and iodine, but you'll need to bring pH paper and chromatography materials. You probably won't need to bring beakers for chromo, but I would double check your rules/tournament info. As for distilled water I am not sure. The rules regarding whether or not to bring it seems to change every year and I don't have a current copy of the rules. Hopefully someone else will be able to better answer your question.
Thanks! I'll check the rules, then.