Advertisements

Welcome to My Chemistry Tutor

Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length

Search for Answers

Custom Search
Use our free chemistry search to search thousands of chemistry homework answers and tutorials

Ask a Question

If you did not find the answer to your chemistry question, join the community and ask for help.

Help Other Students

If you received chemistry help here why not try to help other students. You might undertand something that your peers are having trouble with. If you are in college chemistry you can likely help a high school chemistry student

Find mass of product when given Kc, mass of reactant, but not volume

Pages: [1]
  Print  
Author Topic: Find mass of product when given Kc, mass of reactant, but not volume  (Read 519 times)
Knight
Labrat
*
Posts: 6




« on: January 31, 2010, 09:48:54 PM »

Question:
Assume that at 25 C, with AlCl3 as a catalyst, the following equilibrium can be established between the liquids cyclohexane and methylcyclopentane.
C6H12 <=> C5H9CH3HCH3
Kc = 0.143
If initially 1.00 x 10^2 g cyclohexane is present, what mass of methylcyclopentane will be present in the equilibrium mixture? (Hint: Does the volume of solution matter?)

Attempt:
I attempted to use ICE, but since I do not know the concentration (M) for the reactants, I do not know how to proceed.
I could get the moles of cyclohexane, but then don't I need to convert it to M?

Please advice. Thank you in advance.



Logged
kingchemist
Global Moderator
Hero Member
*****
Posts: 2880

A Liverpool FC fan




« Reply #1 on: February 01, 2010, 03:35:36 AM »
1

You could use density to find the volume of the cyclohexane. (and density of product) However, I wonder if you have to? Could you assume the total volume will not change very much in the reaction and so will be constant. So moles/volume are equivalent to moles. You know moles of cyclohexane (initial).
This would allow you to set up the ICE table. Let change be -x, so change in product = +x and at equilibrium, cyclohexane = moles - x and product = x
hey
Logged

'Chemistry is not just the study of matter; Chemistry is the study which matters!' - Kingchemist
valdorod
Global Moderator
Hero Member
*****
Posts: 566




« Reply #2 on: February 02, 2010, 12:34:22 PM »
2

volumes cancel out for this particular setup

Kc = [C5H9CH3HCH3]/[C6H12]          concentration is moles over volume and the reaction is taking place in the same volume thus....

kc = (mol C5H9CH3HCH3/Vol)/(mol C6H12/Vol)      vol cancels and you end up with

Kc = (mol C5H9CH3HCH3)/(mol C6H12l) 

keep in mind that whis works only because the total exponents on the numerator = total exponents on denominator
hey
Logged

Valdo

CuLaTeRh

Testing a chemistry newsletter, subscribe here and let me know how to improve it.
http://www.epcc.edu/OsvaldoRodriguez/NewsLetter/tabid/11322/language/en-US/Default.aspx
Pages: [1]
  Print  

 
Jump to:  

* Share this topic...
In a forum
(BBCode)
In a site/blog
(HTML)

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!
MyChemistryTutor.com

Idea by BJR Technologies