NaNO2 is used as a preservative for hot dogs and bologna. In acidic solution, ni

Question

NaNO2 is used as a preservative for hot dogs and bologna. In acidic solution, nitrite ion is
converted to nitrous acid, HNO2, which reacts with permanganate ion in the following RXN:

H + (aq) + 5HNO2 (aq) +2MnO4 – (aq) 5NO3 – (aq) +2Mn +2 (aq) + 3H2O (l)

A 1.000 g simple of a water-soluble solid containing NaNO2 was dissolved in dilute H2SO4 and titrated with 0.01000 M KMnO4 solution. The titration required 12.15 mL of KMnO4 solution. What was the (w/w %) of NaNO2 in the original 1.000 g sample?

Explanation / Answer

m = 1 g of sample

M = 0.1 M of KMnO4

V = 12.15 ml of KMnO4

find %

first, find moles of MNO4-

mol = M* V= 12.15*0.01 = 0.1215 mmol of MnO4-

then

the ratio is 5 mol of NO2 per 2 mol of MnO4-

5/2*0.1215 = 0.30375 mmol of NO2- present

since ratio is 1:1 of NaNO2 to NO-2

then

0.30375 mmol of NaNO2 was present

mass = mol*MW = (0.30375*10^-3)*68.9 = 0.0209 g of NaNO2

% sample = mass NaNO2 / sample = 0.0209/1 * 100 = 0.0209*100 = 2.09%

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