Muriatic Acid

Wondering what is muriatic acid and how is it produced & where is it used? I have got you all covered.

What is Muriatic Acid?

Literally, the term muriatic is Latin for “pertaining to brine or salt”, because concentrated salt water is often used as a reagent in its manufacture. Muriatic acid is a form of hydrochloric acid – a corrosive mineral acid that is represented by the chemical formula HCl. Muriatic acid is a diluted form of hydrochloric acid with a pH of about 1 to 2. It often contains impurities such as iron as well. As a result, it is a deeper shade of yellow than pure hydrochloric acid.

Although muriatic acid is still highly corrosive in nature, it is relatively mild compared to pure hydrochloric acid. Thus, it is more suitable for home use. Let us now learn in detail about this acid.

Production of Muriatic Acid

Hydrochloric acid is essentially an aqueous solution of the gas hydrogen chloride (also represented by the formula HCl). Commercially, muriatic acid is produced by dissolving gaseous hydrogen chloride (obtained by the combustion of hydrogen and chlorine gases inside a chamber) in water. The hydrochloric acid thus produced is diluted to the desired concentration to obtain muriatic acid.

H₂(g) + Cl₂(g) → 2HCl(g) → 2HCl(aq)

It is also produced industrially by the reaction of sodium chloride and sulphuric acid.

2NaCl + H₂SO₄ → 2HCl + Na₂SO₄

Alternatively, HCl can be synthesized from sodium chloride, sulfur dioxide, water vapor, and oxygen in the air as shown below:

4NaCl + 2SO₂ + 2H₂O + O₂ → 2Na₂SO₄ + 4HCl

Concentration

There is no standard concentration for muriatic acid in the industry; therefore, it is important to check the product label for the concentration. Generally, industrial suppliers produce muriatic acid that is 31.5 percent HCl by mass. Other dilutions are available in the market and they range from about 14.5 percent to 29 percent.

At a pH of 1 to 2, muriatic acid has acidity comparable with that of gastric juice (that is partly composed of HCl) and lemon juice. However, it is important to remember that the pH level isn’t the sole determinant of an acid’s corrosiveness: muriatic acid (14-29%) is much more concentrated than lemon juice (5-6% citric acid). Thus, it can burn bare skin easily unlike lemon juice.

Uses

Muriatic acid has many industrial as well as domestic uses, many of which involve cleaning or removing one substance from another. Some common uses are:

• Processing raw leather
• Production of gelatin
• Removing the outer layer of pearls
• Commercial synthesis of vinyl chloride and polyvinyl chloride (PVC)
• Descaling
• Cleaning bricks during building construction
• Clearing clogged drains
• Regenerating ion exchange resins
• Production of various inorganic compounds
• Pickling and removal of iron or rust from steel
• Purification of common salt (NaCl)
• Dissolving rocks during the extraction of crude oil
• pH control of food, drugs, and water
• Household cleaning (basements and toilets with mineral stains)
• Digestion of food (in the form of gastric acid)

Safety

Just as knives are useful but potentially dangerous tools, the corrosive qualities of muriatic acid that are advantageous in certain settings make it dangerous to work with – unless proper care is taken.

Hydrochloric acid can cause severe chemical burns to the skin and serious eye damage, even eye damage, if splashed in the eyes. If ingested orally, it can severely corrode the inner lining of the mouth, throat, esophagus, and stomach. Although muriatic acid is a less concentrated form of HCl, it is still capable of causing these injuries.

Therefore, it is essential to take appropriate safety precautions while handling the acid. Let’s discuss these in detail.

Always add acid to water for dilution

If you want to dilute a sample of muriatic acid, always pour the acid into water and not the other way round. Adding water to acid results in an exothermic (heat-producing) reaction that causes the liquid to bubble and splashes all around, possibly landing on your skin or in the eyes and causing injury.

Avoid mixing the acid with other chemicals

Muriatic acid is an effective cleaning agent in its own right; it must never be mixed with other chemicals such as potassium permanganate or bleaching powder. Doing so results in the production of gaseous chlorine that can lead to suffocation and serious health hazards, even death.

Wear protective clothing when working with the acid

Whenever you work with muriatic acid, you must wear protective clothing such as long sleeves, gloves, pants, and glasses or goggles. They will protect you in case any accidental splashes result in the acid landing upon you.

Ensure proper disposal of the acid after you’re done

To dispose of muriatic acid, you must first neutralize it by adding baking soda to it and diluting the resulting solution to a ratio of 1:50. Never pour the acid down the drain without neutralizing it, because it can result in corrosion and environmental damage. It is even better to dispose of the acid by storing it in a plastic bucket and taking it to a hazardous waste disposal facility, if possible.