Examples of corrosive substances and their pH levels
Apr 17, 2018

Examples of corrosive substances and their pH levels

Rachel Chesterfield Rachel Chesterfield

Corrosive substances are destructive materials that pose great risks to people, property and the environment. As corrosive substances pose major risk in our workplaces, it's very important to become familiar with common corrosives used in the workplace and their hazardous chemical and physical properties. An awareness of their hazardous properties will allow you take proactive measures to ensure that they are used and stored in a safe and compliant manner.

What are corrosive substances?

Corrosives substances can be defined as “substances that will destroy and damage other materials and objects with which they make contact.”  This includes, but is not limited to materials such as; metals, organic compounds and living tissues such as human flesh. No doubt we would all know what rusty iron and a corroded batteries looks like - they are simple examples of corrosion.

What is a pH Level?

Simply put, pH is a measurement of how acidic or basic a water-soluble substance is, ranked on a scale between 1 and 14.  A pH level of 7 indicates that a substance is neutral, such as pure water. As the pH level decreases from 7, the substance becomes increasingly acidic.  Anything with a pH level above 7 indicates that the substance is alkaline. Again, as the pH value increases, the alkaline level also increases.

A pH of 4 is ten times more acidic that a pH of 5, and 100 times more acidic than a pH of 6.  Likewise, a pH of 13 is 10 time more alkaline than a pH of 12, and 100 times more alkaline than a pH of 11.

Naturally, the more acidic or more alkaline a substance is, the more effective it will be as a corrosive substance. Highly corrosive substances must be stored in compliant storage facilities such as a corrosive storage cabinet. These cabinets minimise the hazards that corrosive substances pose upon the people in your workplace. We will now discuss some examples of commonly used acids and bases.

Hydrochloric acid

Hydrochloric acid (HCL) has a pH level of 1.1 at 38% concentration.  If this acid accidently came into contact with your eyes or skin, it would immediately begin to dissolve your skin tissue. HCL is commonly used in the production of batteries, fireworks, leather and building materials. It is also commonly used in water and salt purification. Your body also produces Hydrochloric acid to assist your digestive system.

Sulfuric acid

Sulfuric acid (H2So4) has a pH of 0.5 at a concentration of 33.5%, which is equivalent to the concentration of sulfuric acid used in lead-acid batteries. Sulfuric acid is one of the most important industrial chemicals. It plays a part in the production of a lot of manufactured goods.  Despite being primarily used in the production of fertilizers such as superphosphates, sulfates and ammonium phosphates, sulfuric acid is also widely used in the production of dyes, paints, fabric pigments, explosives, lubricants, metals and batteries. Sulfuric acid is a dehydrating agent and it reacts violently with water. When in contact with water, sulfuric acid will boil and splash. If sulfuric acid is released into the atmosphere, it can cause acid rain which is very harmful to the environment.

Nitric Acid

Nitric acid (HNO3) has a pH level of 1.2 at standard commercial concentration of 68%.  The uses of Nitric acid are very similar to those of sulfuric acid. Nitric acid is used in the production of ammonium nitrate, plastics, dyes and explosives such as nitroglycerin and TNT.  When nitric acid is combined with HCL, a fuming liquid, known as aqua regia is formed capable of dissolving gold and platinum. Nitric acid is also utilised in the medical industry to remove warts and as a colorimetric test to distinguish drugs.  When exposed to the skin, nitric acid can cause severe burns, ulceration, dermatitis and yellow staining. As a corrosive substance, nitric acid is capable of dissolving many materials including most metals. For ultimate safety nitric needs to be stored in a compliant safety cabinet to prevent the risk of acid burns and damage to expensive property, plant and equipment.

Chromic Acid

Chromic acid (H2CrO4) has a pH level of approximately 3.03. It is used as a cleaning agent and in the manufacturing of glazes, colored glass and chromium plating. In the past, it has commonly been used as a bleach to dye hair. Due to the high impact chromic acids have on the environment and human health, it’s no longer used for this purpose. Again, chromic acid will burn your skin and safe handling and storage is crucial.

Acetic acid

Acetic acid (CH3COOH) or as we more commonly know it, vinegar, has a pH of 2.4 at 5% dilute solution.  Acetic acid is primarily used in the production of vinyl acetate monomer, followed by ester production and used to create solvents for inks, paints and coatings.  Acetic acid has proved to be widely useful in the medical industry, especially in the treatment of cancer amongst many other conditions such as ear infections. And of course, acetic acid is used in food production.  Surprisingly enough, vinegar is only 4-18% acetic acid by mass. Despite seeming reasonably harmless, acetic acid, specifically in concentrated amounts can be considerably harmful to human health and the environment.

Ammonium hydroxide

Ammonium hydroxide (NH4OH) is a base with a pH of 10.09. It is often used as a glass cleaning agent in various commercial and industrial products.  Ammonium hydroxide is also used as an additive to maintain the correct level of acidity in food items. It is also used as a refrigerant and in the production of detergents, textiles, soaps, ceramics, pharmaceuticals, inks and explosives.  Ammonium hydroxide may cause extensive tissue damage if it is exposed to the skin and therefore it needs to be stored in a safe and compliant manner.

Potassium hydroxide

Potassium hydroxide (KOH) is a base with a pH of 10.98. It is commonly used in the production of fertilizers, biodiesels and soft soaps. Potassium hydroxide is used as an electrolyte and in a process commonly referred to as chemical cremation or resonation.

Sodium hydroxide

Sodium Hydroxide (NaOH) is a base with a pH of 13. Although it is predominantly used in the paper industry, it plays an important role in tissue digestion and in the manufacturing of sodium sales and detergents. Sodium hydroxide is also used as a cleaning agent and as a pH regulator in organic synthesis and metal production. If sodium hydroxide is not handled and stored in a safe corrosive storage cabinet, it can be dangerous to human health and the environment.

Sodium Hypochlorite

Sodium hypochlorite (NaClO) is a base with a pH of approximately 13 at 10-15% concentration. It is used in various industries such as waste management and food production as a bleach or disinfectant. Sodium hypochlorite also has other applications. It is used as an antiseptic in the medical industry and as a pesticide in the agricultural industry.

Next Steps

There are many corrosive substances that are used in the workplace on a regular basis. To minimise harm to the people in your organisation, it’s important to store corrosive substances in a safe manner. One aspect of safe storage is ensuring that class 8 corrosive substances are segregated from other incompatible classes of dangerous goods. For more information on how to segregate corrosive substances from other incompatible classes of dangerous goods, download our free dangerous goods segregation chart by clicking on the image below 👇.

Dangerous Goods Segregation Chart

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