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Vomit comes from gastric acid, right? And in gastric acid there is HCl and HCl is corrosive (strong), how come when I vomit, it doesn't destroy things that it (as the vomit) hits (such as floor, table)?

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2 Answers 2

up vote 28 down vote accepted

First of all, it is corrosive. People which are bulimic often get problems with their teeth getting damaged by the permanent exposure to the acidic stomach fluids. See the paper for more information:

Then it is a matter of concentration. According to Wikipedia, the concentration of the acid in the stomach is around 0.5% which is a pretty low concentration. Additionally the acid gets diluted when you eat or drink things. And last but not least not all things are very susceptible to a fast degradation by acids. Thing tend also not to disappear suddenly, if they come in contact with acids.

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so, the Hollywood "acid spill = instant shaft" is completely false? –  Jan Dvorak Aug 14 at 9:18
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In the way it is usually displayed in films, yes. Take metals for example. A lot of commonly metal will not dissolve (or only slowly). Of course, if you subject Magnesium or pure Aluminium to a strong acid, it will react rather fast. But who uses these metals in this form to build things? –  Chris Aug 14 at 9:25
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Is the Aluminum/Magnesium used in many laptop/tablet/phone bodies alloyed to be much more corrosion resistant than purer forms of the metal? –  Dan Neely Aug 14 at 13:51
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Magnesium is usually used as an alloy, since it is otherwise to hard to work with. Both metals form an oxidative cover on the surface which protects them from further oxidation. And in the case of tablets/phones etc. the surfaces are additionally treated to be much more resistant. –  Chris Aug 14 at 14:22
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@JanDvorak Hollywood lies and exaggerates? Heaven forbid... :) –  Shadur Aug 14 at 17:24

As Chris said it's a matter of a low concentration for a small amount of time. Most people clean up their vomit rather than leave it to sit. Most people who vomit also have recently eaten something which triggers the reflex but also dilutes the acid or may neutralise it.

To further add to Chris' answer. Even heartburn or gastro-oesophageal reflux disease, is particularly corrosive. Damaging cells that line the oesophagus, it causes changes in the cells that make them pre-cancerous (Barret's oesophagus) and can lead to full blown cancer (carcinoma). This is because the cells change type to try to protect themselves.

Even in the stomach a thick layer of mucus is required to prevent the stomach from eating itself. This is not only to protect the lining against its own acid, but the enzymes which are made are seriously dangerous and will digest our body if able, only work in acidic environments. To understand how dangerous they are, when the pancreas which makes these enzymes is blocked releasing these enzymes it can digest nearby structures such as major blood vessels and cause seriously dangerous bleeding.

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