[elifkorkmaz]

   An electroplating wastewater with an average flow of 4 L s-1 contains 258 mg L-1 NaCN. Determine the amounts of chlorine as Ca(OCl)2 and NaOH required to (a) oxidize the cyanide to cyanate; (b) oxidize the cyanide to CO2 and H2O.
should ı solve it according to cl2?

[Borek]

should ı solve it according to cl2?

Is that what you are asked to do?

[elifkorkmaz]

yes this is the question, ı have a similar question but on that question amounts of chlorine was asked. so ı cannot understand what to do

[elifkorkmaz]

He asked the all question, my question is should ı solve it according to Cl2?

[Borek]

No, you have to calculate how much Ca(OCl)₂ should be used. While the process is equivalent to reaction with just chlorine, you don't use chlorine, but Ca(OCl)₂. That's what "chlorine as Ca(OCl)₂" means.

[elifkorkmaz]

I calculated firstly 4L/s x 258 mg/L = 1032 mg/L
then I wrote a reaction like  Ca(OCl)2 + 2H2O <–> 2HOCl + Ca+2 + 2OH-
 2HOCl <-> 2H+ + 2 OCl-
OCl-/ Ca(OCl)2 = 2
mass ratioo = 2x 142.983 (mw of CaOCl)/ 26 = 11 g/g
then; 1032 mg/L x 11 g/g = 11352 mg/s
Is it true?

[elifkorkmaz]

1032 mg/s sorry.

[Borek]

You are asked about amount of substance required to oxidize cyanide, yet there is no cyanide oxidation in your reaction equation.

[elifkorkmaz]

what should I add

[Borek]

Sorry, won't spoon feed you. You are told what are the processes involved, describe each of them with a reaction equation.

[elifkorkmaz]

so further reaction should be 2OCl- + 2CN- <-> 2CNO- + 2Cl-
is it true *?