Nitrite ion, NO^-₂, is a preservative for bacon and other foods, but it is potentially carcinogenic. A spectrophotometric determination of NO^-₂ makes use of the following reactions:

Here is an abbreviated procedure for the determination:

1. To 50.0 mL of unknown solution containing nitrite is added 1.00 mL of sulfanilic acid solution. 

2. After 10 min, 2.00 mL of 1-aminonaphthalene solution and 1.00 mL of buffer are added. 

3. After 15 min, the absorbance is read at 520 nm in a 5.00-cm cell. 

The following solutions were analyzed: 

A. 50.0 mL of food extract known to contain no nitrite (that is, a negligible amount); final absorbance = 0.153. 

B. 50.0 mL of food extract suspected of containing nitrite; final absorbance = 0.622.

C. Same as B, but with 10.0 L of 7.50×10^-3 M NaNO₂ added to the 50.0-mL sample; final absorbance = 0.967.

(a) Calculate the molar absorptivity, , of the colored product. Remember that a 5.00-cm cell was used. 

(b) How many micrograms of NO^-₂ were present in 50.0 mL of food extract?

Transcribed Image Text:

HO S NH, + NO + 2H+I-→ . Sulfanilic acid HO S Ho,s 1-Aminonaphthalene HO.S Colored product,520 nm NH, +H+