chemistry experiments - the snakes of the pharao - burning cough

Something we could not do very well without in our kitchens is Baking soda. Baking soda is a baking aid that helps dough to rise, i.e. give more volume to a dough to make it ‚lighter’. This works because Baking soda releases gases that help the dough to rise. The release of such gases works in a number of ways. Carbon Dioxide is released by adding any acidic solution – for baking soda, this is typically achieved by adding citric or tartaric acid in solid form to the baking powder. When adding water, they dissolve and set off the reaction. A second way of achieving the gas release is heat – Baking soda will decompose into gaseous components at a heat of 50° C or more, which is why your cake continues to rise in the oven. The same process is demonstrated in this experiment.
The Ethanol begins to burn with a blue flame. The "Emser" cough pastilles become more and more bloated in the heat and take on a black colour. Slowly, longer and longer “worms” emerge. The reaction continues until the alcohol has been burnt off.
In addition to their medicinal content, Emser cough pastilles consist of Bicarbonate of soda (baking soda) and sugar. sodiumbicarbonate decomposes from temperatures of 50°C, resulting in Carbon Dioxide and steam.

2 NaHCO3 - > Na2CO3 + CO2 + H2O

Reacting in the heat of the alcohol flame, the sugar content of the pastilles is melted and driven into wormlike shapes by the gases provided by the decomposing Baking soda.
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