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Topic: balanced chemical equation for the reaction of Cu(NO3)2 (aq) with KI (aq)  (Read 25480 times)

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renots

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sry i cant figure the answer to this problem out and its due b4 my lab in like 2 hrs

Write the balanced chemical equation for the reaction of Cu(NO3)2 (aq) with KI (aq) including states. Note: Two of the products are CuI and I2.  Which of the above reactants change oxidation states?  What are the changes?

if anyone could help i would greatly appreciate it.
« Last Edit: February 14, 2006, 06:35:12 AM by Mitch »

Offline Borek

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Re:easy question
« Reply #1 on: February 13, 2006, 11:55:04 AM »
Cu2+ + I- -> CuI + I2

This is not balanced, but that's relatively easy (note: charge must be balanced as well as atoms). Write oxidation numbers near all ions/atoms - which ones are changing?
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renots

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Re:easy question
« Reply #2 on: February 13, 2006, 12:05:31 PM »
what happens to the K and the NO? do they get used up or something?

Offline Mitch

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Re:easy question
« Reply #3 on: February 13, 2006, 12:44:10 PM »
K+ is just a spectator ion, but if you must you can think of KNO3 being formed, but its not accurate way to think.
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renots

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Re:easy question
« Reply #4 on: February 13, 2006, 12:52:59 PM »
Cu(NO3)2 + KI -----> CuI + I2 + X

would the X be kno3, and how would i balance that?  could i take the kno3 completely out of the equation?  when im balancing i just end up going in a never ending circle of increasing coefficiencts

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Re:easy question
« Reply #5 on: February 14, 2006, 02:52:16 AM »
This is a quite easy redox reaction, which can be split into two steps. The fiirst one is a double exchange reaction
Cu(NO3)2 + 2KI = CuI2 + 2KNO3
The next step is a redox one
2CuI2 = 2CuI +  I2

After joining both reaction together (with proper coefficients):
2Cu(NO3)2 + 4KI =
AWK

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Re:easy question
« Reply #6 on: February 14, 2006, 04:50:54 AM »
2CuI2 = 2CuI +  I2

Interesting thing is that this reaction equilibrium is driven by low CuI solubility. Comparison of potentials of both half-reactions (Cu2+/Cu+, I2/I-) suggests that no redox reaction should take place.
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