Topic: Colligative Properties Carbon Tetrachloride Problem (Read 13314 times)

carp14 · « **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.

ARGOS++ · « **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⁺⁺

carp14 · « **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?

ARGOS++ · « **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⁺⁺

carp14 · « **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?

ARGOS++ · « **Reply #20 on:** April 12, 2009, 08:30:07 PM »

Dear carp14;

Please 0.09898 mole/kg and not 0.9898 mole/kg!!
Then it will come fine!

Good Luck!
ARGOS⁺⁺

carp14 · « **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?

carp14 · « **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*

carp14 · « **Reply #23 on:** April 12, 2009, 08:44:54 PM »

Correct Boiling point elevation is 5.03

ARGOS++ · « **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⁺⁺

carp14 · « **Reply #25 on:** April 12, 2009, 08:55:03 PM »

I have no idea what you just said.

carp14 · « **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.

ARGOS++ · « **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⁺⁺

Topic: Colligative Properties Carbon Tetrachloride Problem (Read 13314 times)

carp14

Re: Colligative Properties Carbon Tetrachloride Problem

ARGOS++

Re: Colligative Properties Carbon Tetrachloride Problem

carp14

Re: Colligative Properties Carbon Tetrachloride Problem

ARGOS++

Re: Colligative Properties Carbon Tetrachloride Problem

carp14

Re: Colligative Properties Carbon Tetrachloride Problem

ARGOS++

Re: Colligative Properties Carbon Tetrachloride Problem

carp14

Re: Colligative Properties Carbon Tetrachloride Problem

carp14

Re: Colligative Properties Carbon Tetrachloride Problem

carp14

Re: Colligative Properties Carbon Tetrachloride Problem

ARGOS++

Re: Colligative Properties Carbon Tetrachloride Problem

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Re: Colligative Properties Carbon Tetrachloride Problem

carp14

Re: Colligative Properties Carbon Tetrachloride Problem

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Re: Colligative Properties Carbon Tetrachloride Problem

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