I3^- 0.0500 M Na2S2O3 S2O3^2- 21.55 mL KIO3 mg

I3^- 0.0500 M Na2S2O3 S2O3^2- 21.55 mL KIO3 mg

 

 

2002년 6월, 아일랜드의 보건 아동부는 핵 사고를 대비하여

아일랜드 국가 비상 상태 계획의 일환으로 가정에

아이오딘산 포타슘 정제를 제공하는 프로그램을 시작하였다.

정제 속에 들어있는 KIO3는 몇 mg인가?

 

 

In June 2002, the Department of Health and Children in Ireland began a program to distribute tablets of potassium iodate to households as part of Ireland’s National Emergency Plan for Nuclear Accidents. Potassium iodate provides iodine, which when taken during a nuclear emergency, works by “topping off” the thyroid gland to prevent the uptake of radioactive iodine that might be released into the environment by a nuclear accident. To test the potency of the tablets, a chemist dissolved one in 100.0 mL of water, made the solution acidic, and then added excess potassium iodide, which caused the following reaction to occur.

IO3^- + 8I^- + 6H^+ → 3I3^- + 3H2O

 

The resulting solution containing I3^- was titrated with 0.0500 M Na2S2O3 solution, using starch indicator to detect the end point. (In the presence of iodine, starch turns dark blue. When the S2O3^2- has consumed all of the iodine, the solution becomes colorless.) The titration required 21.55 mL of the thiosulfate solution to reach the end point. The reaction during the titration was

I3^- + 2S2O3^2- → 3I^- + S4O6^2-

 

How many milligrams of KIO3 were in the tablet?

 

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적정에 소모된 S2O3^2-의 몰수를 계산하면,

(0.0500 mol/L) (21.55/1000 L) = 0.0010775 mol S2O3^2-

( 참고 https://ywpop.tistory.com/7787 )

 

 

 

I3^- + 2S2O3^2- → 3I^- + S4O6^2-

 

I3^- : S2O3^2- = 1 : 2 계수비(= 몰수비) 이므로,

0.0010775 mol S2O3^2-와 반응하는 I3^-의 몰수를 계산하면,

I3^- : S2O3^2- = 1 : 2 = ? mol : 0.0010775 mol

 

? = 0.0010775 / 2 = 0.00053875 mol I3^-

 

 

 

IO3^- + 8I^- + 6H^+ → 3I3^- + 3H2O

 

IO3^- : I3^- = 1 : 3 = ? mol : 0.00053875 mol

 

? = 0.00053875 / 3 = 0.0001795833 mol IO3^-

 

 

 

KIO3의 몰질량 = 214.00 g/mol 이므로,

0.0001795833 mol × (214.00 g/mol) = 0.03843 g KIO3

( 참고 https://ywpop.tistory.com/7738 )

 

 

 

답: 38.4 mg

 

 

 

 

[공식] KIO3 질량(mg)

= Na2S2O3 몰농도(M) × Na2S2O3 부피(mL) × (1/6) × 214.00

= 0.0500 × 21.55 × (1/6) × 214.00

= 38.43 mg

 

 

 

 

[키워드] I3^- 0.0500 M Na2S2O3 S2O3^2- 22.61 mL KIO3 mg