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Topic: Calculation of concentration seperating ionic complexes  (Read 4578 times)

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Offline amit25

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Calculation of concentration seperating ionic complexes
« on: February 19, 2013, 09:57:55 PM »
10mL solution of 0.5 M CrCl(OH2)5 2+ is allowed to aquate to Cr(OH2)6 3+. To determine an approximate rate of reaction, the amounts of CrCl(OH2)5 2+ and Cr(OH2)6 3+ present after a certain time are measured by pouring the solution onto a cation exchange
resin in the H+ form and then titrating the displaced H+ with base. If 80 mL of 0.15 M
NaOH is required to neutralize the liberated H+, what were the concentrations of
CrCl(OH2)5 2+ and Cr(OH2)6 3+ in the solution?

Offline AWK

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Re: Calculation of concentration seperating ionic complexes
« Reply #1 on: February 20, 2013, 01:23:52 AM »
You should show your work.
Start from balanced reaction of both form with cation exchange resin (separately).
AWK

Offline amit25

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Re: Calculation of concentration seperating ionic complexes
« Reply #2 on: February 20, 2013, 02:06:23 AM »
CrCl)OH2)5 +2
 
V=10ml c=0.5M
 n=(0.01L)(0.5M)
 n=0.005mol
 
NaOH
 
V=80mL c=0.15M
 n=(0.15M)(80/1000)
 n=0.012mol
 
Total volume=90mL
 c1v1=c2v2
 (0.5M)(10mL)=c2(90ml)
 c2=0.056M
 
im not really sure if im doing this right, any help please :(

Offline amit25

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Re: Calculation of concentration seperating ionic complexes
« Reply #3 on: February 20, 2013, 02:09:31 AM »
Cr(H2O)4Cl2+ + 2H2::equil:: Cr(H2O)5 Cl2+ + Cl- + H2::equil:: Cr(H2O)6 3+ + 2 Cl-
and this is the balanced equation?

Offline AWK

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Re: Calculation of concentration seperating ionic complexes
« Reply #4 on: February 20, 2013, 02:22:51 AM »
You should write down reactions that liberating H+ and do their stoichiometry
AWK

Offline amit25

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Re: Calculation of concentration seperating ionic complexes
« Reply #5 on: February 20, 2013, 04:41:49 PM »
H2O + CrCl(OH2)5 +2  :rarrow: Cr(OH2)6 +3    + Cl-
 
so the ratio is 1:1 for CrCl(OH2)5 +2  and  Cr(OH2)6 +3

the moles for each is n=(0.5M)(0.01L)=0.005mol

??

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