INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

mol concentration graph vs ph scale

mol concentration graph vs ph scale

(OP)
hi guys im a fresh man student in civil engineering

i've been trying for hours but i just cant get grasp of this question.
i would really appreciate a little help!
i know what molarity concentration is but i dnt know anything more than that....

Use the MS excel or MATLAB to draw a pH-Concentration diagram for the three carbonate species in a closed system, hydrogen ion (H+) and hydroxyl ion (OH-). Set pH as the x-axis ranging from 1 to 14, and the molar concentration as Y-axis ranging from 10-1 to 10-14 M, respectively. Assume the total CO2 concentration, [CO2]T = [CO2(aq)]+[HCO3-]+[CO32-]=10-4 M.


RE: mol concentration graph vs ph scale

(OP)
10-1 and 10-14 and 10-4 actually means 10^-1 10^-14 10^-4

RE: mol concentration graph vs ph scale

If you are unfamiliar with acid-base chemistry it is hard to make a crash course in a single post/thread, but here are some basic rules which might help. It all boils down to the chart provided by bimr.

In every CO2-water system there is equilibrium between gaseous CO2, dissolved CO2, and dissociated CO2:

CO2(gas)<--> CO2(aq)
CO2(aq) + H2O <--> H2CO3(aq)
H2CO3(aq)<--> H+(aq) + HCO3-(aq)
HCO3-(aq)<--> H+(aq) + CO3--(aq)

Each of these equilibrium reactions is characterized by the equilibrium reaction constant (K), defined as: http://home.pcisys.net/~bestwork.1/CO2Water/WaterC...

Following two basic rules (conservation of mass and electro-neutrality of the solution), it can be concluded that the initial concentration of dissolved CO2 will be distributed between H2CO3, HCO3-, and CO3-- species. Now, changing pH (which means changing concentration of H+ ions) will affect final concentrations of H2CO3, HCO3-, and CO3-- because the reaction constant K remains unchanged for all reactions, so the concentrations of other contributor(s) in the equation must change. This practically means if you reduce concentration of H+ ions, then the concentration of HCO3- and CO3-- ions must increase. You can see this illustrated on the chart provided by bimr.

pH is negative logarithm of H+ ion concentration (e.g. if H+ conc. is 10E-04 mol/dm3, pH = -log10(10E-04) = 4). If you look at the equations and pH to concentration conversion, now you have 3 equations with 3 unknowns and from there should be easy to start.
You should obtain a chart that looks like http://ion.chem.usu.edu/~sbialkow/Classes/3650/CO2...

Dejan IVANOVIC
Process Engineer, MSChE

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close