NaCl 147.6 mg Hg(NO3)2 28.06 mL 2.000 mL 22.83 mL Cl^- mg/mL

NaCl 147.6 mg Hg(NO3)2 28.06 mL 2.000 mL 22.83 mL Cl^- mg/mL

 

 

The chloride content of blood serum, cerebrospinal fluid or urine

can be measured by titration of the chloride with mercuric ion:

Hg^2+ + 2Cl^- → HgCl2(aq).

When the reaction is complete, excess Hg^2+ reacts with

the indicator, diphenylcarbazone, which forms a violet-blue color.

 

a) Mercuric nitrate was standardized by titrating a solution

containing 147.6 mg of NaCl (FM 58.44),

which required 28.06 mL of Hg(NO3)2 solution.

Find the molarity of the Hg(NO3)2.

 

b) When this same Hg(NO3)2 solution was used

to titrate 2.000 mL of urine, 22.83 mL was required.

Find the concentration of Cl^- (mg/mL) in the urine.

 

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a)

147.6 mg NaCl의 몰수를 계산하면,

147.6 mg / (58.44 mg/mmol) = 2.526 mmol NaCl

= 2.526 mmol Cl^-

( 참고 https://ywpop.tistory.com/7738 )

 

 

 

Hg^2+ + 2Cl^- → HgCl2

 

2.526 mmol Cl^-와 반응하는 Hg^2+의 몰수를 계산하면,

Hg^2+ : Cl^- = 1 : 2 = ? mmol : 2.526 mmol

 

? = 2.526 / 2 = 1.263 mmol Hg^2+

= 1.263 mmol Hg(NO3)2

 

 

 

Hg(NO3)2의 몰농도를 계산하면,

1.263 mmol / 28.06 mL = 0.04501 mmol/mL

= 0.04501 M

( 참고 https://ywpop.tistory.com/3222 )

 

 

 

b)

(0.04501 mmol/mL) × 22.83 mL = 1.028 mmol Hg(NO3)2

= 1.028 mmol Hg^2+

 

 

 

Hg^2+ : Cl^- = 1 : 2 = 1.028 mmol : ? mmol

 

? = 2 × 1.028 = 2.056 mmol Cl^-

 

 

 

Cl^-의 몰질량 = 35.45 g/mol 이므로,

2.056 mmol × (35.45 mg/mmol) = 72.89 mg Cl^-

 

 

 

mg/mL 농도를 계산하면,

72.89 mg / 2.000 mL = 36.45 mg/mL