When bleach comes into contact with oily skin, it forms soap—the combination of an alkaline, non-acidic substance with a fat.

The history of soap and how it forms bathtub scum and white spots in old oil paintings

Soap has been produced since at least 2,200 BCE via a chemical reaction between fats or oils and a base. This creates salts that act as molecular bridges, helping water lift dirt and grease from surfaces. The same chemistry produces scum when metals in hard water bind to soap molecules, as well as white spots in paintings when metal ions in pigments react with fatty acids in the oil binder.

The cleanup of oil and other chemical spills involves a combination of methods tailored to different settings, including vacuuming, dispersing absorbent materials, chemicals, or biological agents, and localized burning.

'Old people' smell is real—it's a chemical buildup when fatty acids on the skin oxidize

The chemical composition of body odor seems to change with age. Later in life, we harbor higher concentrations of a chemical compound called 2-nonenal that forms when omega-7 fatty acids on the skin oxidize, and the skin's natural antioxidant defenses weaken. Commonly called "nonenal", it's the smell widely associated with aging, and it's often described as a grassy or greasy odor.

Odor blockers use nonpolar oils to trap smelly polar molecules

In the case of feces, gut bacteria produce compounds such as skatole and hydrogen sulfide, which the brain registers as unpleasant. Because oils do not dissolve in water, they can be used to create a layer on the surface that prevents smelly compounds underwater from escaping into the air.

Without liver bile, human poop would be a pale silver color

Stomach acid and enzymes break down food into smaller particles, expelling a semi-fluid mass called chyme into the small intestine, where bile is added. As the intestines absorb nutrients and water, the chyme solidifies and changes color.

Alkaline hydrolysis—dissolving the body—is one 'green' burial option

This approach, which is sometimes called flameless cremation, involves dissolving the body with water and chemicals. The remaining bone fragments can then be spread like ashes. It was reportedly incorporated into the funeral industry in 2011.

Learn about unconventional ways to clean up crude oil, including using moss and chickens

Studies show that microorganisms in chicken manure can break down the hydrocarbons in crude oil without producing toxic by-products. Scientists have also explored avoiding the environmental risks of chemical dispersants and synthetic adsorbents by using human hair and peat moss to adsorb crude oil, which can be taken up by their cuticles and porous structures, respectively.

Sweat doesn't smell, but bacteria multiply in moist environments—and cause an odor

Body odor is associated with sweat, but odor actually arises from the bacteria that multiply in moist environments on your skin. Hormones, medications, food, and body hair can all affect body odor.

Laundry detergents designed for cold-water washes rely on proteins isolated from microorganisms native to cold climates, such as Iceland.

Some say soaps have been replaced by reality TV

Reality shows have much in common with soaps: massive melodrama, sweeping music cues, neverending plotlines, and a seemingly endless number of episodes. Some communications scholars suggest that’s why younger viewers are no longer interested in soap operas; reality programs provide the same content with the added appeal of being “real.”

Soaps often air every day, leading to frantic production schedules

Unlike more typical primetime or streaming shows, soap operas often air every weekday. That means writers and actors often work every day to complete a new episode, making for a grueling schedule. It also explains why some of the dialogue and performances might seem a bit off-the-cuff.

Urushiol, the oily toxin in poison ivy, can remain allergenic on clothing for up to 5 years—or even longer.

View a sample of objects surprisingly derived from crude oil, including chewing gum and lipstick

Crude oil processing produces a variety of fuels and the building blocks for plastics, but it also distills out the hydrocarbons used to make aspirin, Teflon, vinyl, crayons, candles, Tupperware, roofing shingles, asphalt pavement, hair dye, anesthetics, food-grade lubricants, polyester, synthetic rubber, and resins for items like dentures.

Scientists have found that kitchen sponges that don't appear dirty or greasy may still harbor bacteria that can cause foodborne illness, and the cleaning items should be discarded regularly, including after wiping surfaces that have come into contact with raw meat.

Soap operas earned their name thanks to the sponsorships of soap brands

Many early 20th-century radio programs for women were sponsored by brands that introduced each new episode. Because these dramas were aimed at women, many of their sponsors were for household products, like soap. The association led some to refer to the shows as "soap operas," a title that stuck.

From glands beneath their skin, hippos produce their own sunscreen in the form of a fluid containing hipposudoric and norhipposudoric acids, which absorb sunlight in the ultraviolet and visible range.

Bath bombs can produce endothermic reactions that cool water

In bath bombs containing citric acid and sodium bicarbonate, water facilitates the reaction between the bicarbonate and acid, providing energy as the salt dissolves. The loss of energy in the water reduces the average speed of the water molecules, reducing the temperature of the bath.

How microbes limited the damage and helped clean up the Deepwater Horizon oil spill

A bloom estimated to contain about 100 sextillion microbial cells broke down much of the 4.1 million barrels of spilled crude oil into nontoxic compounds in what was one of the most significant bioremediations of a human-made disaster. The microbes involved acted similarly to the first patented genetically modified organism in US history: an oil-eating bacterium engineered in 1971.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak annually.

Copper is responsible for turning blonde hair green in swimming pools

Pools use copper sulfate to control algae, which can bind to hair either damaged by the sun or recently bleached. Chlorine, which is often considered to be the culprit, weakens the hair structure to exacerbate the green coloration reaction, rather than causing it.

The adoption of modern appliances led to the soap opera's rise

Soaps grew more popular as they transitioned to television in the 1950s. At the same time, the adoption of modern appliances like the automatic dishwasher and the clothes dryer offered housewives more free time, which soaps could now occupy. By 1970, CBS, NBC, and ABC were airing 18 daytime soaps.

How to create salad dressings with oil and water solutions that don't separate into layers

Such dressings, even when whisked together, often break within a few minutes, resulting in bites that are either harsh or oily. Small amounts of emulsifiers, such as mustard or mayonnaise, can stabilize and suspend oil droplets in water for longer periods because they possess both hydrophilic (water-loving) and hydrophobic (water-repelling) ends.

Poison ivy's rash-causing compound is found in the plant's roots, stem, and leaves—so coming into contact with any part of the plant can lead to rashes for the 85% of people who are allergic to it.

Poison ivy is in the same family as mangoes, cashews, and pistachios, and they all produce oily urushiol in their raw, unprocessed state—but they are typically prepared in ways to avoid causing human discomfort.

The OJ Simpson case interrupted soaps’ daytime dominance, changing the genre

OJ Simpson's 1995 murder trial was broadcast for months, bumping soap operas from the airwaves. Fittingly, the trial provided the same salacious story lines, compelling characters, and open-ended narratives that soaps offered viewers. The key difference, of course, was that the Simpson trial was real life.

Americans only became intolerant of body odor in the last century

Daily bathing only became a societal norm in the last century. Today, Americans routinely bathe and buy more deodorant than any other country, spending roughly $6 billion annually on odor-reducing products. The rise of industrialized soaps, deodorants, and antiperspirants—and extensive marketing around them—stimulated this demand.

See examples of leprosy in the Bible—a broad term for skin ailments in ancient times

People afflicted with leprosy in the Bible may have had a range of different skin diseases, rather than what's clinically diagnosed as Hansen's disease (leprosy) today. In the Bible, as in many traditional societies, those with the disease were often considered unclean or sinful.

Breaking down the challenges of alkaline environments and how extremophiles survive them

These areas are far less acidic than the interiors of most organisms' cells, and this imbalance draws protons that are needed for various metabolic processes, including energy production, out of cells. To counter these effects, some alkaliphiles have developed stronger proton regulation across their cellular membranes and proteins that drive these processes with greater stability amid such acidity imbalances.

Abiogenesis explains how Earth's natural processes could have formed organic matter

The theory details how chemical interactions in hydrothermal vents and shallow ponds billions of years ago could have created lipids, proteins, and RNA. As these interactions involve water, life is thought to have started in oceans.

Carboxylic acids are one reason teens are smelly

Scientists compared the smells of babies and teenagers and identified some of the compounds that make teens smelly. Carboxylic acids present in teens, they wrote, seemed to give off an "earthy, musty, or cheesy" scent. This 2024 research could help inform future odor-control products.

While major oil spills result from accidental pipeline ruptures or damage to transportation vessels or rigs, as much as half the oil that reaches coastlines has naturally leaked from the seafloor.

Why water is the universal solvent, despite not being good at dissolving many substances

Because oxygen attracts electrons much more strongly than hydrogen does in H₂O, the molecule is polar, with a negative charge at the oxygen atom and positive charges at the hydrogen atoms. These charged regions can attract and pull apart charged portions of other polar molecules, such as washable inks, but are unable to dissolve nonpolar materials, such as glass and asphalt.

How chefs suspend liquid in edible pearls resembling caviar to introduce a new texture to fluids

Through spherification, drops of a solution of sodium alginate and a flavored liquid are placed in a calcium lactate solution, which forms a chemical skin around them. This is because calcium replaces the sodium in the alginate chains, forming a gel around each drop's liquid interior.

Learn about historical uses of bioremediation, the oldest cleanup method on Earth

Biochemical reactions that decompose complex molecules into simpler ones have occurred on Earth for as long as life has existed and have gradually transformed the planet into a celestial body that is increasingly habitable to greater biodiversity. Along the way, modern, human-made bioremediation techniques began to take shape in Santa Maria, California, in the 1960s.

A collection of molecular gastronomy techniques, from flavored air to turning oils into powder

Soy lecithin can be blended with flavored mixtures, such as herbs and Parmesan, to produce edible bubbles, which can be frozen into a solid foam. Maltodextrin can be combined with liquid fats in a food processor to create light, flavorful powders.

How the US Department of Energy facilitated bioremediation with emulsified soybean oil

At sites where soil and groundwater were identified as contaminated with volatile organic compounds, scientists and engineers at the Office of Legacy Management used microbes to safely clean them up without more invasive methods, such as pump-and-treat. Treatment zones created at one location by injecting oil to help microbes spread quickly.

Soap operas are long-form, serialized melodramas

The genre was historically aimed at housewives, and its storylines often involve romantic entanglements and family dynamics that transpired over many years. Media scholar Robert J. Thompson called the soap opera “arguably the most unique contribution that broadcasting has made to the art of storytelling.”

During coral bleaching, corals sacrifice their food source and expel colorful microorganisms to protect themselves, a phenomenon that resembles an organism's immune system attacking itself.

Why bacterial bioremediation may help counter the negative effects of past chemical solutions

Molecules such as DDT, a synthetic insecticide, and PFAS—"forever" chemicals used to make products resistant to heat, water, and grease—have historically been used across various industries but are now known to be harmful. Microbes that can convert some of these substances into nontoxic products, such as water and carbon dioxide, have already been identified, with ongoing research to find others.

Blacklights can illuminate certain biological materials, including blood, teeth, and fingernails, because they contain fluorophores—molecules that visibly glow immediately after exposure to higher-energy light.

Explore the chemistry of undesired body odors

This graphic highlights some of the main compounds in different body odors, including halitosis (bad breath), flatulence, and foot odor.

Although PFAS, or forever chemicals, are intentionally designed to be extremely stable and long-lasting because of their strong carbon-fluorine bonds, these bonds can be broken by heat, plasma, and supercritical water.

Why 75% of ocean animals glow

About 75% of ocean creatures can make their own light. It's called bioluminescence—and it all comes down to a special chemical reaction happening inside their bodies.

An overview of crude oil, including its constituent hydrocarbons and refinement outputs

The mixture is primarily composed of molecules of carbon and hydrogen atoms bonded into a variety of shapes and lengths, giving each different chemical properties, such as boiling points. Refining can remove elemental impurities—such as sulfur—after hydrocarbons are separated, ensuring the resulting products can be used effectively in other machines, such as car engines.

Cyanoacrylate, or superglue, was discovered by accident during World War II when researchers tried to create a clear plastic for precision gunsights.

To use the various chemicals in crude oil, they must often be cracked—broken down into smaller molecules—to make their processing easier in everyday machines.

An overview of bioremediation, which can help clean up oil spills, mining waste, and some plastics

The umbrella term refers to a variety of techniques that use organisms to remove harmful substances from an environment or break them down into nontoxic compounds. Because the availability of certain resources can limit the growth of these organisms and impair bioremediation efforts, nutrients such as fertilizers can be deployed to accelerate cleanup.

Although burning most objects causes them to lose mass because some of their solid material turns into gas, metals become heavier when burned because they absorb oxygen.

Soaps launched the careers of countless Hollywood A-listers

Soap operas may not be considered high culture, but many actors who would go on to win television and film’s highest honors got their start with soaps. That includes Julianne Moore (“As the World Turns”), Morgan Freeman (“Another World”), Leonardo DiCaprio (“Santa Barbara”), and Michael B. Jordan (“All My Children”).

Before it was a drink, coffee was used for handwashing.