Pennsylvania

118

Joseph Priestley House, Northumberland, PA

gkat_118.pdf40° 53 25 N, 76° 47 24 W

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Oxygen, Soda Water, and More

The British clergyman and scientist Joseph Priestley is widely credited as the person who discovered oxygen. He also discovered the gases nitric oxide, nitrogen dioxide, nitrous oxide, hydrogen chloride, ammonia, sulphur dioxide, carbon monoxide, nitrogen, and silicon tetrafluoride. And he put the bubbles in soda water.

Prior to Priestley’s work, three “airs” were known: air (as we know it); carbon dioxide (called, at the time, fixed air); and hydrogen. Priestley had observed carbon dioxide in a brewery in Leeds, where it settled over the fermenting beer.

Carbon dioxide is a basic byproduct of fermentation. When yeast ferments, sugar is converted into ethanol and carbon dioxide. Priestley determined that bubbling “fixed air” through water resulted in bubbly water with a pleasant taste. Soda water is simply water mixed with carbonic acid (H2CO3), which is a combination of water (H2O) and carbon dioxide (CO2). It’s carbonic acid that gives soda water its characteristic “bite” when it mildly burns your tongue.

Priestley went on to develop a method of making soda water by mixing water, sulphuric acid (H2SO4), and chalk (calcium carbonate: CaCO3). The acid reacts with ...

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