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Topic: Unknowns University/High School lab  (Read 7277 times)

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Offline Omggg

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Unknowns University/High School lab
« on: October 28, 2008, 09:13:57 PM »
We are given 11 chemicals, and then will be given 5 unknown from those 11 chemicals, we much do tests on them to figure out which is which, cannot use boiling point to find out the chemical

chemicals are

Starch
Boric Acid
Epson salt
table salt
table suger
fructose
baking soda
salicyclic acid
paradichlro benzene
potassium nitrate
Calcium carbonate

i know what to do for some of these, but not all

Any help on testing for these would be good,

Thanks

Offline Arkcon

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Re: Unknowns University/High School lab
« Reply #1 on: October 28, 2008, 10:57:46 PM »
Which ones are giving you the most trouble?  Which ones are you so sure of, you can exclude them from your list of substances you need help with?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline enahs

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Re: Unknowns University/High School lab
« Reply #2 on: October 28, 2008, 10:59:16 PM »
Also, what kind of test will you be able to do/have you learned about.

Offline Omggg

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Re: Unknowns University/High School lab
« Reply #3 on: October 29, 2008, 01:14:51 AM »
Starch
Boric Acid
Epson salt
table salt
table suger
fructose
baking soda
salicyclic acid
paradichlro benzene
potassium nitrate
Calcium carbonate

alright out of those, i know that the boric two of them are acids, so a simple PH reading can tell that.
I am unsure about the differentiate of sugers such as starch,table suger, fructose , and the potassium nitrate

For the potassium nitrate, i can try to react it with NaCl, of something, but i don't know what would happen/take place, so i cannot predict it.

i am also unsure about the differentiate between the two different types of salts.
i am not sure if this would work for the salts,
for espon salt, since it contains Mg, burning it should give me white powder or something, but we are originally given a white powder. so i have no idea what to do there.

we have learned about reactions, using stiochemetry (eg, mole, molarity..), titration, and the other basic experiments..

any help would be nice, thanks.

Offline Arkcon

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Re: Unknowns University/High School lab
« Reply #4 on: October 29, 2008, 11:18:39 AM »

I am unsure about the differentiate of sugers such as starch,table suger, fructose , and the potassium nitrate

OK, let me give you a little hint for fructose vs table sugar.  Look up the definitions of fructose, and the correct chemical name for table sugar.  There may be one word that jumps out at you.  See if you can use it to solve the problem.

Quote
For the potassium nitrate, i can try to react it with NaCl, of something, but i don't know what would happen/take place, so i cannot predict it.

Ummm...read more in your text book.  Terms like "react with NaCl of something" and "happen/take place" are not proper chemical terms.

Quote
i am also unsure about the differentiate between the two different types of salts.
i am not sure if this would work for the salts,
for espon salt, since it contains Mg, burning it should give me white powder or something, but we are originally given a white powder. so i have no idea what to do there.

we have learned about reactions, using stiochemetry (eg, mole, molarity..), titration, and the other basic experiments..

any help would be nice, thanks.

Read.  Read.  Read.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Omggg

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Re: Unknowns University/High School lab
« Reply #5 on: October 29, 2008, 03:49:59 PM »
read what?
there is absolutely no information in my textbook for these chemicals, hence why our instructor chose them.
is there anything you recommend i read for the reactions and their products?

i know that sucrose is fructose and glucose, .. i dont get what your trying to say.

Offline 7453K

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Re: Unknowns University/High School lab
« Reply #6 on: October 29, 2008, 08:50:24 PM »
iodine reacts with starch to make a black/purple. glucose reacts with somethign blue, i cant remember the name. but not methylene blue

Offline Bioionic

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Re: Unknowns University/High School lab
« Reply #7 on: October 31, 2008, 12:38:10 PM »
Benedict's reagent.

Offline Omggg

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Re: Unknowns University/High School lab
« Reply #8 on: January 26, 2012, 03:57:34 PM »
sorry for bumping this old thread.

I wanna give an update as to what happened during my grade 12 lab..

I used flame test with solubility/pH and melting point to figure out most of my stuff..

at the end, I had two salts. the epsom and nacl. both had very high melting points.. 5 minutes left till the end up lab..

I ended up putting the salts in my mouth.. I knew epsom tastes more like sea salt.. I only took one of them in. I KNOW ITS A MISTAKE.. I had no idea salts can be dangerous in grade 12.. lol

so I luckily put NaCl into my mouuth.. I got confused and told my mind that it tastes more like sea salt.. got those two wrong but the others were correct ;)

so fun, yet so risky.. I guess i got lucky. It was 4 years ago :), now im taking some biochem courses in undergrad and back fro some more help..

sorry again for bumping an old thread.. I just thoguht you guys would like to know the result of this experiment. :)

Offline Arkcon

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Re: Unknowns University/High School lab
« Reply #9 on: January 26, 2012, 08:48:07 PM »
Please don't ever taste anything in a university lab again.  Especially the reagents used in biochemical labs -- some might seem to be safe, physiological buffers and such may seem safe, but you never know when they might be contaminated with something really dangerous.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Omggg

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Re: Unknowns University/High School lab
« Reply #10 on: January 26, 2012, 08:53:32 PM »
Please don't ever taste anything in a university lab again.  Especially the reagents used in biochemical labs -- some might seem to be safe, physiological buffers and such may seem safe, but you never know when they might be contaminated with something really dangerous.

lol i realize that now. That was 4 years ago, in high school. I realized that after my organic chem labs .. :)

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