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Colligative Properties Carbon Tetrachloride Problem
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Topic: Colligative Properties Carbon Tetrachloride Problem (Read 13315 times)
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #15 on:
April 12, 2009, 07:14:07 PM »
molality = m
Solute
/ MW
Solute
/ m
Solvent
.
That formula is confusing to me. What is the difference between molecular weight and mass? I can not find the mass of epinephrine, unless it is the molar mass, which is the same as molecular weight.
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ARGOS++
Sr. Member
Posts: 1489
Mole Snacks: +199/-56
Gender:
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #16 on:
April 12, 2009, 07:21:48 PM »
Dear
carp14
;
Think about that your mass of Epinephrine is = 0.64 grams, and your mass of Carbon Tetrachloride is = 22.79 ml times the density.
And:
m
Solute
/ MW
Solute
is nothing else than the number of moles!
I think that this will help you.
Good Luck!
ARGOS
++
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #17 on:
April 12, 2009, 08:00:45 PM »
molality = m
Solute
/ MW
Solute
/ m
Solvent
.
I used some dimensional analyis.
0.64g Epinephrine * (1 mole/ MW Epinephrine) = 64/x
let x = MW Epinephrine
0.9898= (64/x)/ (22.7*1.5842)
35.5945x=64
x=1.79803059
Where did I go wrong?
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ARGOS++
Sr. Member
Posts: 1489
Mole Snacks: +199/-56
Gender:
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #18 on:
April 12, 2009, 08:13:04 PM »
Dear
carp14
;
You are very close!,
- you did only a miner mistake:
You forgot only that you must insert the mass of Solvent in kg (
from the molality definition!
):
22.79 ml * 1.5842 g/ ml = 36.10g = 0.03610kg
If you use it this way you will get the result if you use 0.64g and not 64!!
And please don't round intermediate results!
Good Luck!
ARGOS
++
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #19 on:
April 12, 2009, 08:25:52 PM »
I replaced all the numbers and still did not find the correct molecular weight,
My equation now looks like this.
0.9898= (0.64/x)/0.03610
0.0357= (0.64/x)
0.0357x= 0.64
x= (.64/0.0357)
x=17.9271709
Thats not rite!
Where did I Go wrog now?
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ARGOS++
Sr. Member
Posts: 1489
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Gender:
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #20 on:
April 12, 2009, 08:30:07 PM »
Dear
carp14
;
Please
0.
0
9898 mole/kg
and not 0.9898 mole/kg!!
Then it will come fine!
Good Luck!
ARGOS
++
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #21 on:
April 12, 2009, 08:38:49 PM »
At this point, I need to thank you as you have been more than extremely helpful!
Yet it is bugging me, I solve the equation to 179.11, without any rounding.
The molar mass fo epinephrine is 183.204, why is this?
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #22 on:
April 12, 2009, 08:41:50 PM »
Don't even answer that.
My boiling point elevation is wrong.
I appreciate all your *delete me*
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #23 on:
April 12, 2009, 08:44:54 PM »
Correct Boiling point elevation is 5.03
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ARGOS++
Sr. Member
Posts: 1489
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Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #24 on:
April 12, 2009, 08:50:16 PM »
Dear
carp14
;
I never believe that!,
- Maybe 0.503°K could be possible!
Good Luck!
ARGOS
++
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #25 on:
April 12, 2009, 08:55:03 PM »
I have no idea what you just said.
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carp14
Regular Member
Posts: 18
Mole Snacks: +0/-1
Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #26 on:
April 12, 2009, 08:55:39 PM »
I meant the molal boiling point elevatio constant was wrong, and should be 5.03.
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ARGOS++
Sr. Member
Posts: 1489
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Re: Colligative Properties Carbon Tetrachloride Problem
«
Reply #27 on:
April 12, 2009, 09:00:59 PM »
Dear
carp14
;
That sounds different!,
- But Wikipedia listed 4.95 °K / molal.
Good Luck!
ARGOS
++
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