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Oxidizing and Corrosive hazards in Acid/Base

The corrosivity of a material, that is, the ability for a chemical to cause visible destruction to skin and other tissues is an important parameter in emergency response. The acids are well known for their ability to corrode. A splash of acid on the skin may cause a severe burn and scarring. Though highly dangerous, these materials are used in many industrial processes on a huge scale, and are found in just about every household (for example, cleaners). What makes a material acidic (or basic)? What are the common approaches to dealing with these chemicals in a spill scenario?
GHS-pictogram-rondflam.svgGHS-pictogram-acid.svg
Recall from your early chemistry: Acidic materials dissolve in water to produce a net surplus of hydrogen ions [H+]; ions being electrically charged chemicals in water. Basic materials also dissolve in water and produce hydroxyl ions [OH-]. It is the concentration of these ions which determines the strength of an acid or a base. Strong acids produce higher concentrations of H+ than weak acids (similarly for bases). We can generalize and say that: most common acids have a high solubility in water i.e. you can put them in water, dissolve them and generate ions in solution; a few highly concentrated acids can be flammable and others may be sufficiently oxidizing to ignite combustible materials; acids react with metals, sometimes slowly, to produce flammable and explosive hydrogen gas; acids neutralize bases, in other words, hydrogen ions react with hydroxyl ions to produce water and resultant heat.

pH scale
Acid regionNeutral pHBasic region
pH0-1-2-3-4-5-678-9-10-11-12-13-14
Solutions with pH between 0 and 6 are acid, pH 7 is neutral and pH 8-14 solutions are basic. pH readings may be taken using litmus paper and observing the colour change. The pH scale as shown is a logarithmic scale, that is factors of 10 separate each value. For example, a 1 litre spill of a strong acid (pH=1) would require 10,000 litres of water to be diluted to pH=5. Dilution to neutral pH would require 1,000,000 litres of water (although this wouldn't be necessary as pH=5 would represent a low hazard for skin contact). Addition of water has the added drawback of spreading the spill around.

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