Sparklers are hand-held fireworks that burn slowly while emitting sparks. If a single sparkler is immersed in water, it is extinguished immediately, because water dissipates the heat quickly. However, it is possible to build a sparkler torch which burns under water: To do so, the ignition temperature of approx. 460 ° C has to be kept under water by increasing the number of sparklers (increased thermal energy) and by separating the ignition front and the water from each other (water does not dissipate the heat so quickly).
In the video, ten sparklers are wrapped with Tesa film so that only the tips are free. As soon as all sparklers of this torch are ignited, the torch is dropped head first into a glass filled with cold water.
In the pot of water, water vapor and gaseous pyrolysis products of the Tesa film rise. Various metals react with water vapor to form metal oxides and hydrogen. Example: 4 H2O + 3 Fe → Fe3O4 + 4 H2
The ignitable mass of the sparkler contains 55 parts of barium nitrate, 5 parts of aluminium powder, and 25 parts of iron powder, as well as 15 parts of dextrin as binder.
10 Al + 3 Ba (NO3)2 → 3BaO + 3N2 + 5Al2O3
15 Fe + 4 Ba (NO3)2 → 4 BaO + 4 N2 + 5 Fe3O4
The spark flight is caused by glowing iron particles, which are catapulted to the outside while the sparkler bruns. These not hot iron particles react with oxygen and ignite to magnetite:
3 Fe (s) + 2 O2 (g) → Fe3O4 (s)
Part of the nitrate nitrogen is not completely reduced to the oxidation stage zero, but released as nitrogen dioxide.
2Al + 3Ba (NO3)2 → 3BaO + 6NO2 (g) + Al2O3
- Chemie der Wunderkerze – ein Thema nicht nur in der Weihnachtszeit,
Christina Martin, Tönjes de Vries,
Chemkon 2014, 11 (1), 13–20.