A pH of less than or equal to 2 or greater than or equal to 12.5 is generally considered harmful.
This range defines the levels at which a solution exhibits corrosive properties, posing a risk to human health and the environment. Aqueous solutions with pH values falling outside the range of 2 to 12.5 are classified as hazardous waste under the corrosivity characteristic (D002).
Understanding pH and Corrosivity
pH is a measure of how acidic or alkaline a substance is. It ranges from 0 to 14, with 7 being neutral.
- pH < 7: Acidic
- pH = 7: Neutral
- pH > 7: Alkaline (or basic)
Highly acidic (low pH) and highly alkaline (high pH) substances can be corrosive. This means they can damage or destroy other substances upon contact.
Why These pH Levels Are Harmful
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Extremely Acidic (pH ≤ 2): Strong acids can cause severe burns, tissue damage, and equipment corrosion. Examples include concentrated hydrochloric acid and sulfuric acid.
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Extremely Alkaline (pH ≥ 12.5): Strong bases, like sodium hydroxide (lye), can also cause severe burns, tissue damage, and are dangerous to ingest. They are also corrosive to many materials.
Examples of Harmful Substances
| Substance | pH | Harmful Effects |
|---|---|---|
| Battery Acid | <1 | Severe burns, tissue damage, blindness if splashed in eyes |
| Hydrochloric Acid | <1 | Corrosive to metals, severe burns on skin contact |
| Lye (NaOH) | >13 | Severe burns, tissue damage, can cause blindness if splashed in eyes |
| Drain Cleaner | 13-14 | Can cause severe burns and damage to plumbing |
Safety Precautions
When handling substances with extreme pH levels, it's crucial to take proper safety precautions:
- Wear appropriate personal protective equipment (PPE), such as gloves, goggles, and a lab coat.
- Work in a well-ventilated area.
- Know the proper procedures for handling spills and accidents.
- Consult the safety data sheet (SDS) for specific information about the substance you are using.
