# S.O.S. Mathematics CyberBoard

Your Resource for mathematics help on the web!
 It is currently Thu, 20 Jun 2013 12:46:34 UTC

 All times are UTC [ DST ]

 Page 1 of 1 [ 3 posts ]
 Print view Previous topic | Next topic
Author Message
 Post subject: MolalityPosted: Sat, 28 Jan 2012 18:28:04 UTC
 Member of the 'S.O.S. Math' Hall of Fame

Joined: Sat, 20 Nov 2010 21:17:02 UTC
Posts: 432
What is the molality of a 10.5% by mass glucose (C6H12O6) sol'n? The density of the sol'n is 1.03g/mL

Molality (I call it "Mal") = mol solute/kg solvent
My biggest issue for this question is with getting rid of the 'mL'. I don't know of any other conversion factor to get rid of it. In fact, from the "by mass" part, I got:

10.5 g C6H12O6
---------------
100 g soln

So I I multiply this by:

1.03 g soln
--------------
1 mL soln

I get rid of the "g soln" term, but I don't know how to get rid of the "mL soln" term..

WAIT! I think I got it:
the mass of the H2O = (100 - 10.5g) C6H12O6
I assume that the mass of C6H2O6 = 10.5g

so then Mal = (10.5g)/(100-10.5g)^-3 <-- ^-3 because it has to be in kg...
Is this correct?

Last edited by A-R-Q on Sat, 28 Jan 2012 18:33:19 UTC, edited 1 time in total.

Top

 Post subject: Re: MolalityPosted: Sat, 28 Jan 2012 18:31:48 UTC
 Moderator

Joined: Wed, 30 Mar 2005 04:25:14 UTC
Posts: 12172
Location: Austin, TX
A-R-Q wrote:
What is the molality of a 10.5% by mass glucose (C6H12O6) sol'n? The density of the sol'n is 1.03g/mL

Molality (I call it "Mal") = mol solute/kg solvent
My biggest issue for this question is with getting rid of the 'mL'. I don't know of any other conversion factor to get rid of it. In fact, from the "by mass" part, I got:

10.5 g C6H12O6
---------------
100 g soln

So I I multiply this by:

1.03 g soln
--------------
1 mL soln

I get rid of the "g soln" term, but I don't know how to get rid of the "mL soln" term..

You should know that there is particles, which means if you know the density of a particle...

_________________
(\ /)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination

Top

 Post subject: Re: MolalityPosted: Sat, 28 Jan 2012 18:33:43 UTC
 Member of the 'S.O.S. Math' Hall of Fame

Joined: Sat, 20 Nov 2010 21:17:02 UTC
Posts: 432
A-R-Q wrote:
What is the molality of a 10.5% by mass glucose (C6H12O6) sol'n? The density of the sol'n is 1.03g/mL

Molality (I call it "Mal") = mol solute/kg solvent
My biggest issue for this question is with getting rid of the 'mL'. I don't know of any other conversion factor to get rid of it. In fact, from the "by mass" part, I got:

10.5 g C6H12O6
---------------
100 g soln

So I I multiply this by:

1.03 g soln
--------------
1 mL soln

I get rid of the "g soln" term, but I don't know how to get rid of the "mL soln" term..

You should know that there is particles, which means if you know the density of a particle...

Wait please look at the opening post again

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 1 [ 3 posts ]

 All times are UTC [ DST ]

#### Who is online

Users browsing this forum: No registered users

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forum

Search for:
 Jump to:  Select a forum ------------------ High School and College Mathematics    Algebra    Geometry and Trigonometry    Calculus    Matrix Algebra    Differential Equations    Probability and Statistics    Proposed Problems Applications    Physics, Chemistry, Engineering, etc.    Computer Science    Math for Business and Economics Advanced Mathematics    Foundations    Algebra and Number Theory    Analysis and Topology    Applied Mathematics    Other Topics in Advanced Mathematics Other Topics    Administrator Announcements    Comments and Suggestions for S.O.S. Math    Posting Math Formulas with LaTeX    Miscellaneous