Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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hydrochloric acid : HCl
sodium formiate : HCOONa
Class:
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elem=C
organic
Summary:
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When anhydrous sodium formiate is heated, then it first melts and on further
heating it decomposes, giving a colorless gas. This colorless gas is highly
flammable and forms explosive mixes with air.
Description:
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Put a spatula full of anhydrous sodium formiate in a heat-resistant test tube
and heat the test tube carefully and slowly in the flame of a propane torch:
The solid melts and forms a colorless liquid. On stronger heating, this liquid
starts bubbling or even foaming.
Keep the open end of the test tube near the flame of the propane torch: The gas
mix in the test tube is ignited and it burns with a loud whoosh sound, quite
similar to the sound of burning hydrogen in a test tube.
Allow the test tube to cool down: The colorless liquid solidifies to a solid
white mass.
Add water to the test tube: Part of the white solid dissolves, but this is a
slow process.
While there still is some solid left, add some hydrochloric acid: The remaining
solid quickly dissolves. Some colorless gas is produced, but this only is a
small amount.
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According to literature, sodium formiate decomposes on heating to sodium
oxalate and hydrogen and it also produces sodium carbonate and carbon monoxide.
The production of sodium carbonate and carbon monoxide only occurs at higher
temperature and at relatively low rates. So, the whoosh sound really is due to
formation of hydrogen (probably contaminated with some CO). The solid, which is
formed is mostly sodium oxalate and this dissolves without formation of any
gas. Only a small amount of sodium carbonate i