Calculate ionic concentration

  • #1
Krushnaraj Pandya
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Homework Statement


The ionization constant of ## {(C_2 H_5)}_3 {N}## is 6.4 x 10^(-5). Calculate degree of dissociation in its 0.1 M solution when it is mixed with 0.01 M NaOH solution.

2. The attempt at a solution
the compound gives ##{(C_2 H_5)}_3 {NH+}## and ##OH-##. C is initial concentration of compound=0.1 M and x as degree of dissociation- C*x is final concentration of ##{(C_2 H_5)}_3 {NH+}## and since NaOH is strong electrolyte 0.01 M OH- is present. Since x is small compared to 0.01 we take OH concentration as 0.01. Now (C*x)(0.01)=K. placing 0.1 as C we get x as 6.4 x 10^(-2). However the answer is 6.4 x 10^(-3). Where am I wrong?
 

Answers and Replies

  • #2
Krushnaraj Pandya
Gold Member
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Never mind. I totally forgot to write C in denominator. Silly me.
 
  • #3
epenguin
Homework Helper
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You are saying you now get the same answer as the book? I got the same answer so the book appears to be right. :oldsmile: Question phrasing a bit loose.
 
  • #4
Krushnaraj Pandya
Gold Member
697
73
You are saying you now get the same answer as the book? I got the same answer so the book appears to be right. :oldsmile: Question phrasing a bit loose.
yes, I did- thank you. I was just making a really silly mistake.
 

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