Can't Judge a Powder B

robotman
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Re: Can't Judge a Powder B

Postby robotman » February 5th, 2011, 8:44 am

Also when taking the test, or when practicing, use the name of the test liquid that is given such as H20. Almost all of the judges will dock points for not using the scientific formula.
Oh, I never knew that. Thanks for sharing. c:
Most of the time it's easier to just write the formula anyway, so it's not like it's a hassle. :3
Just Make sure you don't write the wrong formula than you would have problems
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Re: Can't Judge a Powder B

Postby DanielleS » February 17th, 2011, 3:40 pm

Hi, this is going to seem like kind of a stupid question, but I'm a little confused. When a powder is dissolved in water, and there is a color change or the clearness of the water changes (transparent to translucent or opaque) is the powder soluble in water? For some reason, I am having a lot of trouble with solubility and Google isn't helping me too much. Thanks !

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Re: Can't Judge a Powder B

Postby robotman » February 17th, 2011, 3:48 pm

The easiest way is if the powder Totally disappears in water it is soluble (like you see the grains than maybe stir it a bit and than the grains are gone)
If you get a color change totally differant from the powder color (ie the powder is metalic looking and the water turns rustish colored (this most likely wont happen )) there is most likely a reaction that occurs not the powder dissolves with the exception of Cool Aid.

If it is cloudy the best thing to do is see if the powder settles out before saying that it is soluble or not if it doesnt settle out it is soluble if it does it isnt
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Re: Can't Judge a Powder B

Postby DanielleS » February 17th, 2011, 3:51 pm

Thank you very much, I understand it much better now !!

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Re: Can't Judge a Powder B

Postby Cheesy Pie » February 17th, 2011, 6:33 pm

What are some good things to test for at the Regionals - an excessively nervous person :oops:
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Re: Can't Judge a Powder B

Postby robotman » February 17th, 2011, 6:39 pm

the Wiki Has a decent list to start with. Look through some of the old tests on the Test Exchange Wiki also
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Re: Can't Judge a Powder B

Postby Cheesy Pie » February 18th, 2011, 12:16 pm

the Wiki Has a decent list to start with. Look through some of the old tests on the Test Exchange Wiki also

OMFG like thank you tons!!!!!!!!!!! :D

Don't laugh, but in 3 of the 4 tryouts, I had disasters.
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Re: Can't Judge a Powder B

Postby JSGandora » February 22nd, 2011, 4:27 pm

Which sentence(s) would be an observation or inference?

"Once placed in the NaOH, the powder formed a gel."

"Once placed in the NaOH, the powder formed a gel-like substance."

"Once placed in the NaOH, the powder formed an alloid."

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Re: Can't Judge a Powder B

Postby robotman » February 22nd, 2011, 4:51 pm

The third one for certain.
the other two would be fine in my book
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Re: Can't Judge a Powder B

Postby kcmom » February 24th, 2011, 1:14 pm

Hello! I'm a mentor and I need a bit of help! Can we bring a graduated cylinder with us? We don't see that it is specifically mentioned, so we are afraid to bring it and get disqualified. However, we have noticed that some of the practice questions ask for the volume of the powder.

Would it be provided by the person running the event?

Thank you!


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