How Soap Works

How Soap Works Soaps are sodium or potassium fatty acids salts, produced from the hydrolysis of fats in a chemical reaction called saponification. Each soap molecule has a long hydrocarbon chain, sometimes called its tail, with a carboxylate head. In water, the sodium or potassium ions float free, leaving a negatively-charged head. Key Takeaways: Soap Soap is a fatty acid of a salt.Soaps are used as cleansers and lubricants.Soap cleans by acting as a surfactant and emulsifier. It can surround oil, making it easier to rinse it away with water. How Soap Cleans Soap is an excellent cleanser because of its ability to act as an emulsifying agent. An emulsifier is capable of dispersing one liquid into another immiscible liquid. This means that while oil (which attracts dirt) doesnt naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed. The organic part of natural soap is a negatively-charged, polar molecule. Its hydrophilic (water-loving) carboxylate group (-CO2) interacts with water molecules via ion-dipole interactions and hydrogen bonding. The hydrophobic (water-fearing) part of a soap molecule, its long, nonpolar hydrocarbon chain, does not interact with water molecules. The hydrocarbon chains are attracted to each other by dispersion forces and cluster together, forming structures called micelles. In these micelles, the carboxylate groups form a negatively-charged spherical surface, with the hydrocarbon chains inside the sphere. Because they are negatively charged, soap micelles repel each other and remain dispersed in water. Grease and oil are nonpolar and insoluble in water. When soap and soiling oils are mixed, the nonpolar hydrocarbon portion of the micelles break up the nonpolar oil molecules. A different type of micelle then forms, with nonpolar soiling molecules in the center. Thus, grease and oil and the dirt attached to them are caught inside the micelle and can be rinsed away. The Disadvantage of Soap Although soaps are excellent cleansers, they do have disadvantages. As salts of weak acids, they are converted by mineral acids into free fatty acids: CH3(CH2)16CO2-Na HCl → CH3(CH2)16CO2H Na Cl- These fatty acids are less soluble than the sodium or potassium salts and form a precipitate or soap scum. Because of this, soaps are ineffective in acidic water. Also, soaps form insoluble salts in hard water, such as water containing magnesium, calcium, or iron. 2 CH3(CH2)16CO2-Na Mg2 → [CH3(CH2)16CO2-]2Mg2 2 Na The insoluble salts form bathtub rings, leave films that reduce hair luster, and gray/roughen textiles after repeated washings. Synthetic detergents, however, may be soluble in both acidic and alkaline solutions and dont form insoluble precipitates in hard water. But that is a different story... Sources IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).  Archived. Klaus Schumann, Kurt Siekmann (2005). Soaps.  Ullmanns Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH.   Thorsten Bartels et al. (2005). Lubricants and Lubrication.  Ullmanns Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH.​

Halifax Explosion of 1917 - World War I History

Halifax Explosion of 1917 - World War I History Updated: 07/13/2014 About the Halifax Explosion The Halifax Explosion occurred when a Belgian relief vessel and a French munitions carrier collided in Halifax Harbour during World War I. Crowds gathered around to watch the fire from the initial collision. The munitions ship drifted towards the pier and after twenty minutes blew sky high. More fires started and spread, and a tsunami wave was created. Thousands were killed and injured and much of Halifax was destroyed. To add to the disaster, a snowstorm started the next day, and lasted for nearly a week. Date December 6, 1917 Location Halifax, Nova Scotia Cause of the Explosion Human error Background to the Halifax Explosion In 1917, Halifax, Nova Scotia was the main base of the new Canadian Navy and housed the most important army garrison in Canada. The port was a major hub of wartime activity and Halifax Harbour was crowded with warships, troop transports and supply ships. Casualties more than 1900 people killed9000 injured1600 buildings destroyed12,000 houses damaged6000 homeless; 25,000 people with inadequate housing Summary of the Explosion The Belgian relief vessel Imo was leaving Halifax Harbour on its way to New York and the French munitions ship Mont Blanc was on its way to wait for a convoy when the two ships collided at 8:45 am.The munitions ship was carrying picric acid, gun cotton and TNT. Her top deck carried benzol which spilled and burned.For 20 minutes crowds collected around Halifax Harbour to watch the billowing smoke filled with sparks and fire as the Mont Blanc drifted towards Pier 6. While crews from nearby ships raced to put out the blaze, the captain and crew of the Mont Blanc rowed in lifeboats for the Dartmouth shore. When the crew landed they tried to warn people to run.The Mont Blanc rammed Pier 6, setting its wood pilings on fire.The Mont Blanc exploded, flattening everything within 800 metres (2600 feet), and causing damage for 1.6 km (1 mile). The explosion was said to have been heard as far away as Prince Edward Island.Fires spread quickly after the explosion.Water around the ship vaporized, a huge tsunami wave flooded the streets of Halifax and Dartmouth and swept many people back into the harbour where they drowned. The next day, one of the worst blizzards ever recorded in Halifax began, and lasted for six days.Relief came immediately from the troops in the area. Assistance also poured in from the Maritimes, central Canada and the northeastern United States in the form of medical supplies and workers, food, clothing, building supplies and labourers, and money. Emergency teams from Massachusetts arrived, and many stayed for months. To this day, the people of Nova Scotia remember the help they received, and every year the province of Nova Scotia sends a giant Christmas tree to Boston in thanks.