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![[Post New]](/templates/default/images/icon_minipost_new.gif) 11 Nov 2007 16:01:26 IST
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1) The composition of a sample of wustite is Fe0.93O1.00. What % of iron is present in the form of Fe(III)? 2)If in diamond, there is unit cell of carbon atoms as fcc and if carbon atom is sp3 what fractions of void are occupied by carbon atom? (A) 25% Tetrahedral (B) 50% Tetrahedral (C) 25% Octahedral (D) 50% Octahedral 3) Fe3O4 is ferromagnetic. Why? Explain using concepts of solid state. For the next two ques, i require only the answer,i will ask for calculations if my answer wud not match urs i) Polonium crystallizes in a simple cubic unit cell. It has an atomic mass = 209 and density = 91.5 Kg m-3. What is the edge length of its unit cell? ii) Xenon crystallizes in face centre cubic lattice and the edge of its unit cell is 620pm. What is the radius of xenon atom? Plz reply soon for assured rates....
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-Anonymous |
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11 Nov 2007 16:44:48 IST
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q1) Fe0.93O1.00 = Fe93O100 The charge on 93 units of Fe should be 200 for the molecule of wustite to remain neutral. Let x units be of charge 3 and remaining 93-x would be of charge 2. .: 3x + 2(93-x) = 200 => x = 14 % of +3 Fe = 14/93*100 = 15.05%
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11 Nov 2007 19:34:48 IST
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ans 1) wrong answer...ans must be 11.5
this composition i.e Fe0.93O1.00 instead of FeO is becoz some Fe2+ ions are replaced by Fe3+ ions
this formula implies that 93 atoms of Fe combine with 100 atoms of O...
out of 93 let Fe3+ ions = x, Fe2+ = 93-x
as the compound is neutral , total charge on Fe2+ & Fe3+ ions = charge on 02- ions
3.x + 2(93-x) = 2.100
x = 14
Fe3+ = 14
so Fe2+ = 79
so the formula becomes
Fe2+0.79 Fe3+.14 O2-1.0
total mol mass = 0.93.56 + 1.16
= 68.08g
Fe3+ present = .14 x 56 = 7.84
% age = (7.84/68.08)*100
= 11.5%
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frnds are like diamonds , if u hit them , they don't break but they slip frm ur hands
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11 Nov 2007 19:36:01 IST
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ur xenon qs ans 219.25 pm
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I always like to walk in rain as no one can see me crying there :(
frnds are like diamonds , if u hit them , they don't break but they slip frm ur hands
-----It is better to be hated for what you are than to be loved for what you are not.----
*****wen love and skill work together--expect a masterpiece*****
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11 Nov 2007 19:38:36 IST
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Fe3O4 is ferrimagnetic...i think so
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I always like to walk in rain as no one can see me crying there :(
frnds are like diamonds , if u hit them , they don't break but they slip frm ur hands
-----It is better to be hated for what you are than to be loved for what you are not.----
*****wen love and skill work together--expect a masterpiece*****
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11 Nov 2007 19:58:00 IST
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no himanshu i m afraid u r wrong about the first ques, joyfrancis's answer exactly matches with the answer that i have
actually u have calculated the percentage taking in consideration oxygens mass, the ques was to calculate Fe(III)'s percentage out of total iron present in the compound
ur xenon's answer matches mine thank u
and i will rechk whether it was ferrimagnetic or ferromagnetic....
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Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.
-Albert Einstein
Generally people who take the piss out of other people hang around in groups of five, because they have a fifth of a personality each.
- Eddie Izzard
It's my life
And it's now or never
I ain't gonna live forever
I just wanna live while I'm alive
-Bon Jovi
By the time a son realizes that his father was probably right, he has a son who thinks he is wrong.
-Anonymous |
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12 Nov 2007 12:50:39 IST
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please check ur answer again...confirm with ur sir....
m again getting the same answer...plzz check...
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I always like to walk in rain as no one can see me crying there :(
frnds are like diamonds , if u hit them , they don't break but they slip frm ur hands
-----It is better to be hated for what you are than to be loved for what you are not.----
*****wen love and skill work together--expect a masterpiece*****
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12 Nov 2007 17:19:47 IST
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chimanshu leave that ques, try others, i m more than sure its rite
and yeah its ferromagnetic only
anyone gettinf the 2nd ques, i think its easy but aint getting...
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Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.
-Albert Einstein
Generally people who take the piss out of other people hang around in groups of five, because they have a fifth of a personality each.
- Eddie Izzard
It's my life
And it's now or never
I ain't gonna live forever
I just wanna live while I'm alive
-Bon Jovi
By the time a son realizes that his father was probably right, he has a son who thinks he is wrong.
-Anonymous |
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13 Nov 2007 23:03:42 IST
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heloo guys waiting for the second ques.........
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Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.
-Albert Einstein
Generally people who take the piss out of other people hang around in groups of five, because they have a fifth of a personality each.
- Eddie Izzard
It's my life
And it's now or never
I ain't gonna live forever
I just wanna live while I'm alive
-Bon Jovi
By the time a son realizes that his father was probably right, he has a son who thinks he is wrong.
-Anonymous |
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