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Processing KODAK Motion Picture Films, Module 3, Analytical Procedures • H24.03 9
Example Potentiometric Calculations:
Hypo Index (HI) or Total Reductants:
Thiosulfate (S
2
O
3
=
):
Sodium Sulfite (Na
2
SO
3
):
Titration mL 0.1 N Na
2
S
2
O
3
Titrant
Blank A = 40.50
Sample A = 21.85
Blank B = 40.55
Sample B = 19.80
HI (1), mL =
(40.50 – 21.85)(0.0989)
0.1000
= 18.4 mL 0.1000 N I
2
g/L S
2
O
3
=
=
(40.55 – 19.80)(0.0989)(112.13)(1000)
(2.0)(1000)
= 57.5 g/L
g/L Na
2
SO
3
=
[(40.50 – 21.85)(2.0) – (40.55 – 19.80)](0.0989)(63.02)(1000)
(2.0)(1000)
= 51.4 g/L