• Support PF! Buy your school textbooks, materials and every day products Here!

Solution of NaCl and CO2. Name species and find concentrations of species.

  • Thread starter geostudent
  • Start date
  • #1
So, I'm assuming no Sodium Bicarbonate or Carbonate is formed during this process.

I found the concentrations of the species by basic ICE diagram.

Mostly, I need to know how to approach this problem conceptually . I'm assuming the effect of NaCl on the CO2-->H2CO3-->HCO3- --> CO3-- is negligible, but I really don't know. This is for a geochem class, and I have very little chemistry experience, so any explanations or theory would help tremendously.


Homework Statement



Problemset 3.

1. Consider and NaCl solution into which we introduce CO2 by bubbling gas. Recipe: 10-3M NaCl, 10-4M [CO2]T.
(a) What species are present?

(b) What reactions take place?

(c) What is the concentration of the species

(d) Now add 10-4.5M [NaOH]T .What is the alkalinity of the solution?

H2CO3*=H++HCO3-; pK1=6.3 (I)
HCO3-=H++CO32-; pK2=10.3 (II)


Homework Equations





The Attempt at a Solution




(a) What species are present?

Species present are Na+ , Cl-, H+, OH-, HCO3- , CO32- , H2CO3 and CO2 (aq), Na2CO3, NaHCO3


(b) What reactions take place?

(c) What is the concentration of the species


[HCO3-]= 2.07E-5
[H+] ~ 2.07E-5
[CO32-]=5.62E-11

[Na+] = .001 M

[Cl-] = .001 M

[HCO3-]= 2.07E-5

Using this below.


H2CO3 HCO3- + H+ pKa1 (25 °C) = 6.37
HCO3-  CO32- + H+ pKa2 (25 °C) = 10.25


H2CO3 HCO3- + H+ pKa1 (25 °C) = 6.37 Ka1=4.3E-7
HCO3-  CO32- + H+ pKa2 (25 °C) = 10.25 Ka2 =5.62E-11


H2CO3 HCO3- H+
I 1E-3 0 0
C -x +x +x
E .001-x x x

Ka1= [HCO3][H]/[H2CO3] = x2/ .001-x = 4.3E-7

[H+]=[HCO3-]=2.07E-5


The second dissociation contributes very little [H+] =5.62E-11


[H+] ~ 2.07E-5

[CO32-]=5.62E-11

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
Borek
Mentor
28,360
2,753
NaCl presence changes ionic strength of the solution, so it slightly changes equilibrium concentrations of all ions present in the solution. Not enough to make it a problem.

x2/ .001-x = 4.3E-7
.001 or .0001?
 
  • #3
.0001. Sorry.
 

Related Threads on Solution of NaCl and CO2. Name species and find concentrations of species.

Replies
5
Views
811
  • Last Post
Replies
1
Views
2K
Replies
8
Views
8K
Replies
3
Views
6K
Replies
1
Views
2K
Replies
14
Views
9K
Replies
1
Views
2K
  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
6
Views
8K
Top