| View previous topic :: View next topic |
| Author |
Message |
Clairenix
Grandmaster Cheater
 Reputation: 5
Joined: 19 Dec 2007
Posts: 715
|
 Posted: Tue Dec 16, 2008 3:13 am Post subject: Chemistry help, - Limiting reagent |
 |
|
Help please,
At high temperatures, sulfur combines with iron to form the brown-black iron (II) sulfide:
Fe (s) + S (l) → FeS (s)
In one experiment, 7.62 g of Fe are allowed to react with 8.67 g of S.
What is the limiting reagent?
I did this:
Given:
7.62g Fe
8.67g S
Unknown: L.R
Fe(s) + S(l) --------> FeS(s)
already balanced
nFe = 7.62g/55.85 g/mole = 0.14 mole
nS = 8.67g/32.06 g/mole = 0.27 mole
then
0.14 moles of Fe x 1 mole of S / 1 mole of FE = 0.14 moles of S
0.27 moles of S x 1 mole of Fe / 1 mole of S = 0.27 moles of Fe
My conclusion:
S is the limiting reagent therefor should be controlled for it will be consumed first in the reaction.
but then the document said the answer was this:
Answer Key
1. a. Fe is the limiting reagent.
Where did I go wrong?
_________________
|
|
| Back to top |
|
 |
Daaamon
Grandmaster Cheater Supreme
 Reputation: 0
Joined: 12 May 2007
Posts: 1443
Location: Southern California
|
| Posted: Tue Dec 16, 2008 3:31 am Post subject: |
|
|
I failed chemistry, I fucking suck at this shit
It's the only thing I EVER had trouble with in school... EVER.
_________________
|
|
| Back to top |
|
|
Clairenix
Grandmaster Cheater
Reputation: 5
Joined: 19 Dec 2007
Posts: 715
|
| Posted: Tue Dec 16, 2008 3:36 am Post subject: |
|
|
anybody wanna actually help? :<
_________________
Last edited by Clairenix on Tue Dec 16, 2008 3:56 am; edited 1 time in total |
|
| Back to top |
|
|
Daaamon
Grandmaster Cheater Supreme
Reputation: 0
Joined: 12 May 2007
Posts: 1443
Location: Southern California
|
| Posted: Tue Dec 16, 2008 3:40 am Post subject: |
|
|
I was good with electron configuration
1s2 2s2 2p2 2p3 yadda yadda
_________________
|
|
| Back to top |
|
|
xlcs
Grandmaster Cheater
 Reputation: 0
Joined: 14 Nov 2006
Posts: 945
|
| Posted: Tue Dec 16, 2008 3:59 am Post subject: Re: Chemistry help, - Limiting reagent |
|
|
| bryan2394 wrote: | Help please,
At high temperatures, sulfur combines with iron to form the brown-black iron (II) sulfide:
Fe (s) + S (l) → FeS (s)
In one experiment, 7.62 g of Fe are allowed to react with 8.67 g of S.
What is the limiting reagent?
I did this:
Given:
7.62g Fe
8.67g S
Unknown: L.R
Fe(s) + S(l) --------> FeS(s)
already balanced
nFe = 7.62g/55.85 g/mole = 0.14 mole
nS = 8.67g/32.06 g/mole = 0.27 mole
then
0.14 moles of Fe x 1 mole of S / 1 mole of FE = 0.14 moles of S
0.27 moles of S x 1 mole of Fe / 1 mole of S = 0.27 moles of Fe
My conclusion:
S is the limiting reagent therefor should be controlled for it will be consumed first in the reaction.
but then the document said the answer was this:
Answer Key
1. a. Fe is the limiting reagent.
Where did I go wrong? |
I don't really understand what did you do here:
0.14 moles of Fe x 1 mole of S / 1 mole of FE = 0.14 moles of S
0.27 moles of S x 1 mole of Fe / 1 mole of S = 0.27 moles of Fe
In my opinion, you already have the answer when you got
nFe = 7.62g/55.85 g/mole = 0.14 mole
nS = 8.67g/32.06 g/mole = 0.27 mole
According to the equation, Fe(s) + S(l) --------> FeS(s)
1 mole of iron reacts with 1 mole of sulphur to produce 1 mole of iron sulphide
Thus, 0.14 moles of iron can only react with 0.14 moles of sulphur, making Fe the limiting reagent.
(I could be wrong?)
|
|
| Back to top |
|
|
Clairenix
Grandmaster Cheater
Reputation: 5
Joined: 19 Dec 2007
Posts: 715
|
| Posted: Tue Dec 16, 2008 4:11 am Post subject: |
|
|
Well that does make sense,
Heres the lecture from my notebook:
81g of Al was made to react with 490g h2SO4
determine L.R.
Given:
81g Al
490g H2SO4
Unknown L.R.
Al+H2SO4 -------> Al2(SO4)3 + H2(g)
then balance it
2Al + 3H2SO4 -------> Al2(So4)3+3H2(g)
then get moles
nAl= 81.00g / 26.98 g/mole = 3 mole
nH2SO4 = 490g / 98.06 g/mole
mole to mole relationship
3 mole of Al x 3 moles of H2SO4 / 2 moles Al = 4.50 moles of H2SO4
5.00 moles h2SO4 x 2 moles Al / 3 moles H2SO4 = 3.33 moles of Al
LR = Al
Al is the limiting reagent therefor should be controlled because it will the first to be consumed in the reaction.
_________________
|
|
| Back to top |
|
|
*Mario*
Expert Cheater
 Reputation: 0
Joined: 06 Nov 2007
Posts: 106
Location: Ah... Don't look behind you.
|
| Posted: Tue Dec 16, 2008 5:25 am Post subject: Re: Chemistry help, - Limiting reagent |
|
|
| bryan2394 wrote: | Help please,
At high temperatures, sulfur combines with iron to form the brown-black iron (II) sulfide:
Fe (s) + S (l) → FeS (s)
In one experiment, 7.62 g of Fe are allowed to react with 8.67 g of S.
What is the limiting reagent?
I did this:
Given:
7.62g Fe
8.67g S
Unknown: L.R
Fe(s) + S(l) --------> FeS(s)
already balanced
nFe = 7.62g/55.85 g/mole = 0.14 mole
nS = 8.67g/32.06 g/mole = 0.27 mole
then
0.14 moles of Fe x 1 mole of S / 1 mole of FE = 0.14 moles of S
0.27 moles of S x 1 mole of Fe / 1 mole of S = 0.27 moles of Fe
My conclusion:
S is the limiting reagent therefor should be controlled for it will be consumed first in the reaction.
but then the document said the answer was this:
Answer Key
1. a. Fe is the limiting reagent.
Where did I go wrong? |
fe & s
no numbers or anything, so 1 for 1 transfer
pretty much for this you just needed to look at what there was less of, Iron.
So Fe is the answer.
Fag.
Better explanition is,
Fe & s > FeS or w/e
If it were Fe & 2S > FeS then S would be the limiting reagent, because there would be more enough iron to make the FeS but not enough sulfer.
So yeah, Fe is the right answer.
_________________
|
|
| Back to top |
|
|
Clairenix
Grandmaster Cheater
Reputation: 5
Joined: 19 Dec 2007
Posts: 715
|
| Posted: Tue Dec 16, 2008 5:30 am Post subject: Re: Chemistry help, - Limiting reagent |
|
|
| *Mario* wrote: | | bryan2394 wrote: | Help please,
At high temperatures, sulfur combines with iron to form the brown-black iron (II) sulfide:
Fe (s) + S (l) → FeS (s)
In one experiment, 7.62 g of Fe are allowed to react with 8.67 g of S.
What is the limiting reagent?
I did this:
Given:
7.62g Fe
8.67g S
Unknown: L.R
Fe(s) + S(l) --------> FeS(s)
already balanced
nFe = 7.62g/55.85 g/mole = 0.14 mole
nS = 8.67g/32.06 g/mole = 0.27 mole
then
0.14 moles of Fe x 1 mole of S / 1 mole of FE = 0.14 moles of S
0.27 moles of S x 1 mole of Fe / 1 mole of S = 0.27 moles of Fe
My conclusion:
S is the limiting reagent therefor should be controlled for it will be consumed first in the reaction.
but then the document said the answer was this:
Answer Key
1. a. Fe is the limiting reagent.
Where did I go wrong? |
fe & s
no numbers or anything, so 1 for 1 transfer
pretty much for this you just needed to look at what there was less of, Iron.
So Fe is the answer.
Fag.
Better explanition is,
Fe & s > FeS or w/e
If it were Fe & 2S > FeS then S would be the limiting reagent, because there would be more enough iron to make the FeS but not enough sulfer.
So yeah, Fe is the right answer. |
Oh thanks but you didn't have to insult me >_>
_________________
|
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
