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

Mixing ratio Check please

  • Thread starter Nimmy
  • Start date
  • #1
41
0
A typical global concentration of hydroxii radicals (OH) is about 10^6 moleculues/cm^3. What is the mixing ratio corresponding to this concentration at sea level P = 10^5 Pa and T=298 K?


Using the previous equations derived earlier

ndOH= (P*Av/R*T)*COH
(ndOH*R*T/(P*Av) ) = COH

(10^6 molecules/cm^3)*(1 cm/100 m)*(1 cm/100 m)*(1 cm/100 m) = 1 molecule/m^3

((1 molecule/m^3 )*(8.314 J/mol*K)*(298 K)/(10^5 Pa)(6.022*10^23)) = COH

2477.572/6.022*10^23= 4.11*10^-21

Is this process correct? Thanks.
 

Answers and Replies

  • #2
157
0
There are 100 cm per meter not the other way around.
 
  • #3
41
0
Thanks but otherwise the correct process right?
 
  • #4
157
0
[itex] PV= nRT = NkT [/itex]
where N is number of particles, k is boltzman's constant, n is number of moles, and R is the gas constant.

[itex] C_{particles} = N/V = P/{kT} [/itex]

[itex] mixing ratio = C_{OH}/C_{total particles} = N_{OH}/N_{total particles} [/itex]

[itex] N_{OH}/N_{total particles} = {N_{OH}}/{{PV}/{kT}} = {10^6}/(({10^5}*{.01^3})/({1.381*10^{-23}}*{298}}) = 4.115*10^{-14} [/itex]

You can keep doing it in moles if you want to but it just adds an extra step when you are being given the number of particles already. Looks like you did it right except for the unit conversion.
 
Last edited:

Related Threads for: Mixing ratio Check please

  • Last Post
Replies
16
Views
1K
  • Last Post
Replies
1
Views
961
  • Last Post
Replies
1
Views
929
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
10
Views
1K
  • Last Post
Replies
3
Views
7K
Top