Sodium hypochlorite (NaOCl) is widely recognized and used, most commonly encountered in its diluted liquid form as household bleach. Its strong oxidizing properties make it an effective agent for disinfection, stain removal, and general cleaning. The chemical’s origin traces back to the 18th century, when the invention of this stable liquid solution marked a significant technological leap forward from inefficient, centuries-old methods of purification and whitening.
Setting the Stage: Chemical Innovation in the 18th Century
The discovery of sodium hypochlorite was preceded by a revolution in chemical understanding during the 18th century. A fundamental precursor was the isolation of chlorine gas by Swedish chemist Carl Wilhelm Scheele in 1774. Scheele produced this gas by reacting the mineral pyrolusite with hydrochloric acid.
Chemists quickly recognized the powerful bleaching action of chlorine gas. However, the gas was highly corrosive and difficult to handle or transport safely. The established method for bleaching textiles was a slow, laborious process involving soaking fabrics and spreading them out in the sun for weeks. This inefficiency created a strong incentive to harness chlorine’s power in a stable, liquid form.
The Discovery and Initial Formulation by Claude Louis Berthollet
French chemist Claude Louis Berthollet successfully stabilized chlorine’s bleaching power in the late 1780s. Berthollet demonstrated that chlorine gas could be dissolved into an alkaline solution to create a practical, liquid bleaching agent. This formulation marked the discovery of the precursor to modern liquid bleach.
In his laboratory in the Javel quarter near Paris, Berthollet initially passed chlorine gas through a solution of potash (potassium carbonate). This reaction yielded potassium hypochlorite, the very first stable liquid bleach. The new product was named eau de Javel, or Javel water, after its manufacturing location.
This solution achieved in hours what the old sun-and-field method required weeks to accomplish. Although the initial formulation was potassium hypochlorite, the fundamental innovation—the creation of a stable, transportable hypochlorite solution—was complete. The year 1789 is often cited for the first production of this modern bleaching liquid.
Transition to Industrial Bleaching Agent
The industrial adoption of eau de Javel was swift, particularly by the booming French textile industry. The ability to rapidly whiten fabrics transformed the manufacturing process, cutting down the time and space required for production. However, the initial formulation used potash, which was a relatively expensive alkali source.
To make the process more cost-effective for mass production, chemist Antoine Labarraque refined the formulation. He replaced the costly potash lye with the much cheaper soda lye, or sodium hydroxide. This substitution resulted in the production of sodium hypochlorite, the compound that forms the basis of modern household bleach.
The shift to the sodium compound made the product commercially viable for widespread industrial use. This newer, cheaper sodium-based solution became known as Eau de Labarraque and solidified hypochlorite’s place as a foundational industrial chemical.
Present-Day Applications and Dilution Guidelines
While its origins lie in the textile industry, sodium hypochlorite’s application quickly expanded into public health and disinfection in the 19th century. Today, its primary uses include disinfecting surfaces, sanitizing food contact areas, and purifying water supplies. The active ingredient works by chemically oxidizing and destroying the cell structures of bacteria, viruses, and fungi.
Household bleach is typically sold as a 5.25% to 8.25% sodium hypochlorite solution, which must be diluted for safe use. For general household surface disinfection, a common recommendation is to mix one part bleach with nine parts water, creating a 1:10 dilution. This dilution ensures effective pathogen kill while minimizing corrosive effects and fume production.
Bleach should never be mixed with acidic cleaners, such as vinegar or toilet bowl cleaner, because this combination generates toxic chlorine gas. Mixing it with ammonia-containing products can also produce harmful chloramine fumes. Proper use involves diluting the product with cold water and applying it for a recommended contact time, usually at least ten minutes, before rinsing.