Here and on the following page. describe the preparation of 12 ml. of a 0.050 M

Question

Here and on the following page. describe the preparation of 12 ml. of a 0.050 M solution of each of the halogens, using the reactions in the preceding question. Available to you are solid Ca(OCI)_2: 0.20 M solutions of NaCL, NaBr, BaBrO_3 and CuSO_4 a 0.40 M solution of Nal; a 0.50 M solution of H_2SO_4 distilled water, and a 10-mL graduated cylinder (where volumes can be read to the nearest 0.1 mL). Calculate the required quantity of each reagent and the volume of water that must be added for dilution. Chlorine water Iodine water

Explanation / Answer

The required solution is 12mL of 0.050 M

a) For chlorine water

Moles of chlorine required = Molarity X volume (L) = 0.050 X 12 / 1000 = 0.0006 moles

So we need twice the moles of H+ = 2 X 0.0006 = 0.0012 moles

Moles of OCl- needed = 0.0006 moles

moles of Cl- = 0.0006 moles

we have H2SO4 solution , so volume of H2SO4 required = moles / molarity = 0.0012 / 0.50X 2 = 0.0012 L = 1.2mL

We have divided with "2" as each mole of h2SO4 will give two moles of H+.

2) we have solid Ca(OCl)2,

Mass required = Moles X molar mass = 0.0006 X 143 g / mole = 0.0858 grams

3) the NaCl solution is 0.2 M

so for 0.0006 moles the volume needed is

Volume = Moles / molarity = 0.0006 / 0.2 = 0.003 L = 3mL

Total volume used = 3 + 1.2 = 4.2 mL

Volume of water needed = 12 - 4.2 = 7.8 mL

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