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Offline Rutherford

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Equilibrium issue
« on: April 03, 2012, 12:26:28 PM »
How many percents of iodine will dissociate on 1273K if the density of iodine vapors toward hydrogen in this temperature is 92?
How can I calculate it without the Keq? How to use the density towards hydrogen? 92*2=184g of I2?

Offline Olympiad_Tutor

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Re: Equilibrium issue
« Reply #1 on: April 03, 2012, 01:13:03 PM »
can you get density out of PV=nRT?

what's relative density?
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Offline Rutherford

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Re: Equilibrium issue
« Reply #2 on: April 03, 2012, 02:01:46 PM »
p=mRT/(MV)
m/V=d
p=dRT/V
What to do now? What is that relative density?

Offline Olympiad_Tutor

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Re: Equilibrium issue
« Reply #3 on: April 04, 2012, 03:09:26 PM »
relative density here is 184.

since we are chemists we want to deal with moles and molar masses.

what exactly does density(I2)/density(H2) mean in this case?
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Offline Rutherford

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Re: Equilibrium issue
« Reply #4 on: April 05, 2012, 07:42:44 AM »
Don't have a clue. I only know that it is 92. Could you explain it more clearly?

Offline Olympiad_Tutor

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Re: Equilibrium issue
« Reply #5 on: April 05, 2012, 10:07:12 AM »
i am sorry. i meant the relative density is 92 as per your problem.

you need to plug that in and focus on mollar mass ratios.
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Offline Rutherford

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Re: Equilibrium issue
« Reply #6 on: April 05, 2012, 10:23:52 AM »
density(I2)/density(H2)=92
m(I2)/M(H2)=92
m(I2)=92*2=184
So, what to do now?

Offline Olympiad_Tutor

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Re: Equilibrium issue
« Reply #7 on: April 05, 2012, 12:20:33 PM »
what's the molar mass of I2. what's the molar mass of your mixture? why are they different?
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Offline Rutherford

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Re: Equilibrium issue
« Reply #8 on: April 05, 2012, 12:38:54 PM »
Hard for me to understand because I never done similar problems before and I there is no explanation in my book.Is this right:
The mass of the mixture is 184g, and the molar mass of I2 is 254g, so 70g dissociated?

Offline Olympiad_Tutor

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Re: Equilibrium issue
« Reply #9 on: April 05, 2012, 05:37:32 PM »
write the equation of dissociation, come up with the formula for the average weight: we started with 1 mole, x moles dissociated, etc.

the average weight of the mixture is dependent on x, so is Keq.

what's your formula for the average weight of your mixture?
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Offline Rutherford

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Re: Equilibrium issue
« Reply #10 on: April 06, 2012, 07:20:56 AM »
 I2 ::equil:: 2I
1-x      2x
[m(I2)+m(2I)]/2=... is this 184?

Offline Olympiad_Tutor

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Re: Equilibrium issue
« Reply #11 on: April 07, 2012, 01:22:55 AM »
we have 6 apples 80 g. each and 8 apples 60 g. each, what's the average weight of an apple?
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Offline Rutherford

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Re: Equilibrium issue
« Reply #12 on: April 07, 2012, 03:40:13 AM »
10.42g?
How to use it here?
I2 ::equil:: 2I
1-x      2x
[m(I2)+m(2I)]/2=... is this 184?
Why is this wrong?

Offline Olympiad_Tutor

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Re: Equilibrium issue
« Reply #13 on: April 19, 2012, 12:58:39 PM »
how can it be 10.42 g.? the smallest apple weights 60 g.
it is a good idea to check if the answer makes sense.


>>>[m(I2)+m(2I)]/2=... is this 184?

why do you divide by 2? you will get the same value regardless of the degree of dissociation. how is it useful for anything?
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Offline Rutherford

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Re: Equilibrium issue
« Reply #14 on: April 20, 2012, 10:57:33 AM »
The average weight is of an apple is 70g. Could you please write how to solve this?

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