The Bismuth-Sodium Nitrate Reaction William D. Hill, Jr. North Carolina Central University, Durham, NC 27707 A reaction involving lead and sodium nitrate (1-2)
.nromnted . the idea to execute a reaction involvine bismuth and sodium nitrate with the anticipation of obtaining bismuth(II1) oxide, substance obtained by heating bismuth(111) sulfide in air (3), the thermal decomposition of bismuth(V) oxide (4). and the thermal decom~ositionof bismuth(1Ii) nitrate (5). Six supplies of a combination of 41.80 g (0.20 g atom) of bismuth and 34.00 g (0.40 mol) of sodium nitrate were heated in suitable-size casseroles one at a time under an open hood and over a Bunsen burner flame until all the sodium nitrate melted and until yellow substances appeared. The casserole contents, after they were removed from the casseroles and pulverized, were placed in containers of distilled water. The resultine solutions were filtered. washed six times with 1L of colldistilledwater, washed six times with 1 L of hot distilled water, and given ample time to dry. The yellow solids were found to weigh 46.5893,46.5895,46.5896, 46.5896,46.5897, and 46.5899 g, respectively. This implies a 46.5896-g average, a 0.00013-g average deviation, a 0.00014-g standard deviation, and a 99.997% yield based on bismuth. Each product was combined as one. A sample of the combined products was subjected to a reaction with a hot partially dilute mineral acid,and a sample of this combination was subjected to a reaction with water a t various temneratures. Silver nitrate was added to the filtrates and to the washing remains. A white . nreci~itate . was formed in the filtrates but not in the washing remains. The color, the yields, the reaction with a hot partially dilute mineral acid, the reaction with water at various temperatures, the formation of a white precipitate in the filin the washing trates, and the formation of no remains sufficed to show that bismuth(II1) oxide was produced by executing the bismuth-sodium nitrate reaction. Bismuth(II1) oxide is soluble in a hot, partially dilute mineral acid and when the acid is completely concentrated, but it is insoluble in water at various temperatures. Silver nitrite was the white precipitate obtained when silver nitrate reacted with the filtrates, and the f a d that it did not form in the washine remains indicated that the bismutb-sodium nitrate reaction was complete. The formation of this white ~ r e c i ~ i t aindicated te that sodium nitrite was the byproduci of the executed reaction. 'Chis silver nitrate test for nodium nitrite is better than reacting sodium nitrite with an acid and an excess of an iron(llJ salt of that acid to produce nitric oxide, which reacts with the unreacted
iron(I1) salt to produce Fe(NO)+ (6)because sodium nitrate undergoes this reaction also. All the unreacted sodium nitrate was removed from the desired product in the respective washings as indicated by the yields and by the yellow color in the flame test for sodium. 2Bi 3NaN0, Bi,03 + 3NaN02 BizOs+ 6H+ 2Bi3++ 3H20 Bi03+ H,O -no reaction AgNO, + NaNO, AgN0,L NaNO,
+
--
+
are the equations for the reactions based on the above-stated observations. Fire extinguishers and other needed items inclusive of safety goggles were available if anything analogous to what happened in previous encounters with sodium nitrate had taken place (7-9). Unlike the heating of ammonium dichromate (101, this reaction can and will be assimed to those in eeneral chemistry for preparing bismuth(111)oxide and for determining the actual vield, the theoretical . vield,. and the percent vield for bismu
