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MiniWalkingExplosive
Probably not a bot. Junior Member.
Joined: 26 May 2007
Posts: 3
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 Posted: Sat May 26, 2007 2:38 am Post subject: URGENT HELP PLEASE! |
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 I have an assignment to identify 5 out of 11 unknown white solids for chemestry and a HUGE portion of our grade depends on it so if you can give us help or hints or ideas w.e anything would help please and thank you and if you have any links.... just basicly anything. THANKS! here are the chemicals we have to identify ^^"   :S
Sodium Chloride
Sodium Bicarbonate: i think vingar would be good?
Sodium carbonate
sodium hydroxide
boric acid
calcium sulfate
calcium carbonate
corn starch: iodine?
fructose
sucrose
magnesium sulfate
again thank you for your kindness and help much apperaceted. <3
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RobJim
Senior Member
Joined: 13 Feb 2005
Posts: 320
Location: Los Angeles, CA
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| Posted: Sat May 26, 2007 3:01 am Post subject: |
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What resources will you have investigating? Just visual, or do you get access to a chem lab?
First - get access to as many of these chemicals as you can ahead of time and carefully observe it. Look at it, shake it around, see if it dissolves in water, maybe see if it dissolves in other common solvents, etc. Read about each of them on Wikipedia whether or not you have the chem lab access.
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MiniWalkingExplosive
Probably not a bot. Junior Member.
Joined: 26 May 2007
Posts: 3
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| Posted: Sat May 26, 2007 6:16 am Post subject: |
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ah well i dont get to handle the substances untill the day of the lab and i need to do physical and chemical results anything that will identify it and if i do something i need to say why i cant just say cuz it looks like cornstarch =/ so ya but thank you for ur suggestion ^_^
o and i did look at resources =/ kinda confusing and unhelpful.... some were pretty helpful but mostly it was just about the chemical it's self or pH testing and stuff =/
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RobJim
Senior Member
Joined: 13 Feb 2005
Posts: 320
Location: Los Angeles, CA
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| Posted: Mon May 28, 2007 9:15 pm Post subject: |
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My first instinct is to test water solubility. At least some of those chemicals are water soluble. I don't know if any are insoluble. Wikipedia has this information. For example,
http://en.wikipedia.org/wiki/Sodium_carbonate
shows that Na2CO3 has a water solubility of 30 g/100 mL. Sucrose, which we all know is very soluble in water, has a solubility of 212 g/100 mL, which means that Na2CO3 should be much harder to dissolve in water than table sugar.
NaCl has a water solubility of 36 g/100 mL, but this is at a slightly higher temperature (25 deg. C). This is also better than that of Na2CO3, though these solubilities should be checked at the same temperature using the CRC Handbook or something similar.
Now, let's look at calcium sulfate. According to the Wiki, it's water solubility at 20 deg. C is 0.24 g/ 100 mL. Thus we can differentiate it from the others based on solubility.
Now you have two tools; inspection and solubility tests. Find the water solubility at room temperature for each of these substances and make sure the units match and the temperatures are the same.
Simplicity is key at first. You can try chemical tests for further info, but start with simplicity.
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MiniWalkingExplosive
Probably not a bot. Junior Member.
Joined: 26 May 2007
Posts: 3
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| Posted: Thu May 31, 2007 5:39 pm Post subject: |
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XD ahahaha ya ^^" we started testing yesterday and we already used water and vinigar and we already have a clue to what the solids might be one becomes hot w water and vinigar and the other is cold w water.
also we got baking soda, plaster, and corn starch lucky huh? xD
THANK YOU SO MUCH FOR UR HELP SIR! ^_^ have a happy forth of july!
 i know i willl BWAHAHAHHAHAHAHHAHAHAHAHHA
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dr. dugmore
Junior Member
Joined: 03 Jun 2007
Posts: 4
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| Posted: Sun Jun 03, 2007 6:30 am Post subject: |
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| put all the chemicals into their chemical formulas first, i have dont this assignment before it makes it easier
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cynthia joffrion
Junior Member
Joined: 15 Jun 2007
Posts: 5
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| Posted: Fri Jun 15, 2007 3:17 am Post subject: Tables |
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| Yes I have done the same and it worked.
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RobJim
Senior Member
Joined: 13 Feb 2005
Posts: 320
Location: Los Angeles, CA
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| Posted: Fri Jun 15, 2007 6:20 am Post subject: |
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| MiniWalkingExplosive wrote: |
XD ahahaha ya ^^" we started testing yesterday and we already used water and vinigar and we already have a clue to what the solids might be one becomes hot w water and vinigar and the other is cold w water.
also we got baking soda, plaster, and corn starch lucky huh? xD
THANK YOU SO MUCH FOR UR HELP SIR! ^_^ have a happy forth of july!
i know i willl BWAHAHAHHAHAHAHHAHAHAHAHHA |
One becomes hot with water and vinegar and the other is cold with water...that sounds like there's an exothermic reaction with water with the one (vinegar has water in it I believe). Possible there's an endothermic reaction with water with the other one; did the solution get colder when the solid was mixed in or did it just stay cold?
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