Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: onefear on March 28, 2008, 02:06:23 PM
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hi i need help please i need someone to work out a formulae and word equation for me please so i know what happened in my test tube lol :)
i added copper(II) sulphate to water and added a magnesium ribbon (that started the sacraficial protection) i got bored so i added potassium iodide i now im left with a huge amount of iodine and something dark green at the bottom what happened and whats left???
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Can you start to work out this problem by expressing those substances by their chemical formulas? And seeing what reactions will go forward.
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well at the moment i have the unreacted formulae
Mg+2 + Cu(II)SO-2 + KI
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oops mistake there
Cu(II)SO-2 + H2O + Mg+2 + KI
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MgO + Cu(III)SO + K20 + i + H2
is it something like that??
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Oh no hold on i forgot the 5H2O in the sulphate
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This forum does have an option available to you to edit previous posts, ya know.
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Cu(II)SO4-2+5H2O + H2O + 3Mg+2 + 6KI -> 3MgO + 3K2O + I + Cu(III)SO4-2 + 6H2
oops ok i didnt know thanks emm would it be something like this? will the Mg an K take the oxygen out of th sulphate to???
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Well, lets try to break it down some. First off, since this reaction occurs in aqueous solution, the 5 H2O molecules attached to each CuSO4 don't really have to be accounted for, not while surrounded by the rest of the water.
You started with:
CuSO4 and Mg, right, what should have started to happen? Hint:look up a table of electronegativity.
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a right th Mg changes Cu(II) to something hold on im still reading
by the way im 15 so ive not bein doing chemistry long lol
Mg is 1,83 and Cu is 1,65 what ever that means lol :) (im trying here)
im sorry i dont get the electronegativity :) but what i do know is the electron from the Mg go to the Cu because the Mg is higher in the E.C.S so does Cu (II) become Cu(IIII) <<< i think thats impossible but im just guessin here
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Look at the table of electronegativities. At one end is gold and platinum, you see those all the time, they're always shiny, you'll often see copper and iron around as well, often, not as shiny. Look at the other end, metals like sodium and potassium, you don't see those lying around often, do you? Where do copper and magnesium fit in the sequence? And what are they closer to?
by the way im 15 so ive not bein doing chemistry long lol
Not to worry, the laws of chemistry remain the same no matter how old you are. ;)
Mg is 1,83 and Cu is 1,65 what ever that means lol :) (im trying here)
im sorry i dont get the electronegativity :) but what i do know is the electron from the Mg go to the Cu because the Mg is higher in the E.C.S so does Cu (II) become Cu(IIII) <<< i think thats impossible but im just guessin here
Nope, that's not what happens, but you're trying. Read up a bit, and then come on back with some other theories.
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ok Mg is right up the left beside K which is furthest left and Cu is sort in the middle we btty right o the middle
and yeah i know that metal like potassium are very reactive with oxygen and are never found in there pure form and gold is very unreactive and doesnt react with oxygen
so oooooooo.. magnesium wont be touched because there is a bigger gap between potassium and copper??
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ok Mg is right up the left beside K which is furthest left and Cu is sort in the middle we btty right o the middle
and yeah i know that metal like potassium are very reactive with oxygen and are never found in there pure form and gold is very unreactive and doesnt react with oxygen
So close ...
so oooooooo.. magnesium wont be touched because there is a bigger gap between potassium and copper??
And yet so far.
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OOOOOOOOOOOO potassium will just react with the oxygen in the water!! and magnesium will react with the copper and the oxygen in the water
man your making a bigger fool of me than im making of myself lol :)
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No, write a single replacement reaction.
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ah so the Mg+2 swaps with Cu(II)SO-2 to make Mg+2SO-2 + Cu????
btw i check the test tube it smells like the iodine and sulphur have joined and the metals have sunk to the bottom
AAAAAAAAa so the Mg never reacts with oxygen.
and the potassium reacts with the copper
so then i get potassium oxide and the copper is separate ??
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Well Arkcon was doing a good job but you seemed to miss the big picture. This experiment deals with several things, the reactivity of metals, ionic dissociation, solubility and reactivity. And sulfate is SO4-2. Magnesium ribbon is Mg0 not Mg2+. Please show all your steps sequentially.
Can you write a single replacement reaction?
Also don't smell things unless you know what is going on.
This may help
http://professormeyer.com/images/solubility%20chart.jpg
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Also don't smell things unless you know what is going on.
Everything agrobert: says is very important, but I did want to re-iterate this one point. You high school chemistry book will tell you the proper way to smell chemical reactions, by wafting fumes towards your nose without inhaling. Oh, and it explains the other stuff we've mentioned.
Can you write the magnesium and copper sulfate reaction now?
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To the OP...
Please take your time to explain yourself and get your explanations right. Help will come your way if you patiently and thoroughly explain what's going on.
Please stop writing SO for sulphate... Seriously. It's not how it is written and nobody will understand what you mean.
The initial reaction is a simple reduction-oxidation reaction, Mg is oxidising into Mg2+ and Cu2+ is reducing to Cu.
The reaction for the following would be: Cu2+(aq) + Mg(s) --> Mg2+(aq) + Cu(s)
As for the precipitate? Could it be the insoluble Copper (I) Iodide? It's not green but may appear so in the remaining Cu solution.
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i know how to smell things properly :D oh and thanks mrOHBrown makes sense now (not all of it yet but gettin there.)
just to let you know our schools so poor we dont have chemistry books just get lectured and write note and that part we havent been taught yet.. i suppose the money goes towards the chemicals not the books i should be glad of that lol