The acid test
By Jon Elsworth
Bristol University, UK.
Acids - the stuff of horror films, burning faces off hapless victims, disposing of bodies, covering evidence. But while some are nasty, others are very useful and provide us with the ability to eat, digest and reproduce. This month we feature a series of acids - some well known, others less so, but all fascinating.
Acetic acid 
Common name: Vinegar, Ethanoic acid
Classification: Organic acid
Properties: Colourless liquid with a very characteristic pungent odour. Named from the Latin for vinegar, acetum, it is used widely as a preservative and condiment.
Effects: Capable of disintegrating concrete at concentrations greater than 30%. Reactive with metals and will remove mineral deposits left after hard water evaporates. Tastes great on fish and chips with a bit of sodium chloride.
Danger rating (1-5): * * Fairly noxious when pure but pretty darned tasty when dilute.
Citric acid 
Commonly found: Lemon juice
Classification: Organic acid
Properties: Colourless crystalline acid found in fruit juices such as lemon, lime and pineapple. Essential component of the citric acid cycle or “Krebs cycle” responsible for aerobic respiration and energy production.
Effects: Will dissolve a steel nail in a matter of hours and corrode concretions. Also tastes great in the correct concentration but better on lemon sole than cod.
Danger rating (1-5): * * Not a strong acid and essential for living.
Phosphoric acid 
Commonly found: Fizzy drinks
Classification: Inorganic acid
Properties: Colourless, odourless liquid used in the production of agricultural fertilizers and insecticides. Also found in carbonated beverages such as Coca-Cola.
Effects: Has applications in the steel industry to clean and rust-proof their products. Provides a tart, acidic flavour to food stuffs and will rot your teeth away without a second thought.
Danger rating (1-5): * * * Weak acid, but don’t drink too much of it.
Hydrofluoric acid 
Common name: Hydrogen fluoride
Classification: Inorganic acid
Properties: Colourless, fuming liquid or gas. Used in electroplating, the semi-conductor industry and to etch glass. Toxic and corrosive.
Effects: Attacks glass, concrete, some metals and anything that contains silica. Must not be stored in glass bottles! Has a high affinity for calcium and readily penetrates the skin to destroy our bones. A killer in a matter of hours.
Danger rating (1-5): * * * * Not a strong acid but a potential killer.
Triflic acid 
Common name: Trifluoromethanesulfonic acid
Classification: “Super acid”
Properties: Colourless, fuming liquid. Has an acidity 100 times greater than pure sulfuric acid, hence its superiority. Used for a variety of purposes in the synthesis of organic compounds.
Effects: Surprisingly resistant to oxidation but extremely corrosive, especially towards plastics and will dissolve skin in seconds. Avoid at all costs.
Danger rating (1-5): * * * * * KEEP CLEAR! It is a “super acid” after all.
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