Salt

Salt

 

Salt, or sodium chloride, is an ionic compound that has significantly impacted civilization, is necessary in the body for electrical conductivity, depolarization, and propagation of action potentials, and is one of the most soluble compounds in water. Salt contains two atoms, sodium and chlorine atoms. Each atom has the opposite electric charge; a solution of sodium chloride conducts electricity due to the dissociation of sodium and chlorine ions in solution. The positive ends of the water molecule surround the chlorine atoms and each negative end of the water molecule surrounds the sodium ions. The oxygen atom in the water molecule is more electronegative, thus it possesses a slightly negative charge and the hydrogen atoms possess a slightly positive charge because the shared electrons in the covalent bonds spend a majority of the time around the oxygen atoms; the uneven orbiting of electrons is a result of a difference in electronegativities amongst the two types of atoms engaging in covalent bonding. Salt, since it attracts water molecules and dehydrates the product it is contained in at high quantities, it acts as a preservative because the bacteria that cause decay flourish in an aqueous environment. Whenever an axon membrane or a muscle membrane prepares to contract or depolarize, the voltage-gated sodium channels open at -50mv and an influx of sodium ions rush into the cytoplasm. Since sodium ions play such a role in conducting messages from neuron to neuron and from neuron to an effector, vital body processes could be maintained and homeostatic equilibrium could be maintained. The mineral that contains a very high solubility in water is halite, which contains a very high amount of salt. Arrhenius, a Swedish chemist, proposed that ionic compounds such as salt dissociate into charged species or ions and conduct electricity in solution and acids and bases increase the concentration of hydrogen/hydroxide ions in solution. Sodium chloride’s molecular structure is a crystal lattice that contains each ion bonded to as many oppositely charged ions as possible; the electrostatic forces that hold the molecule together are so strong that the compound is a solid at SATP and in order to break the crystal lattice, an electric current has to be passed through the substance at a high enough voltage, this is a chemical reaction that is referred to as electrolysis. Sodium ions play an important role in the human body by generating electric impulses to transmit information and the sodium-potassium pump restores the resting membrane potential at -70mv through the active transport of sodium and potassium ions, requiring the hydrolysis of ATP. A lack of sodium in the body causes vascular collapse, cramps, nausea, and a loss of weight and appetite. Excess consumption of salt leads to a high blood pressure because a higher concentration of solids in the bloodstream has to be accompanied with reabsorption of water from the filtrate in the kidneys into the bloodstream, thus increasing the blood volume and pressure. Since sodium ions are constantly being secreted into the filtrate and removed from the body through renal excretion, we have to replace the supply of salt in our bodies through our diet. Sodium chloride is a compound that is responsible for the salt trade and monopoly, economic growth, industrial advances, and supporting necessary processes in the body at the cellular level. The price of salt has declined over periods of time in history due to the efforts of many chemists and scientists to derive cheaper methods of producing and isolating the compound. The isolation of salt involves extracting salt from salt solutions in brine springs, mining for salt rock, and evaporating sea water. Solar evaporation of sea water is a cheap method of producing salt in coastal region, however it is very time-consuming. Since the volume of the solvent declines, the excess solute crystallizes out of the solution due to insolubility. The salt solutions in brine springs were extremely concentrated, often ten times more concentrated than seawater. Brine salt is not contaminated with calcium chloride and magnesium chloride, it is more expensive than salt obtained through solar evaporation, and it is not an effective enough preservative because calcium and magnesium chloride also absorb water from the air. Salt rock or halite are remains of old oceans and seas that are solid nowadays. Many settlements flourished around these halite deposits and mines that extracted salt, which promoted economic growth, wealth, and the growth of cities and towns. The salt trade involved areas such as the Sahara dessert, the Mediterranean regions, and the west coast of Africa. Saharan salt has been transported to Europe at high quantities due to the increasing demand for salt; various products such as herring and cod had to be preserved with salt as well. The salt monopoly and trade has caused the economy to flourish in different parts of the world and the taxation on salt lead to high profit margins. The tariffs and taxes applied on salt has been very lucrative. The salt tax has been abolished in the United Kingdom in 1825 and in 1923; the salt tax has doubled on Indian citizens. Mahatma Gandhi has been responsible for increasing the access to salt for Indian citizens through non-violent civil disobedience. Another compound, soda ash or sodium carbonate, is a material that is used to produce soaps. The production of soda ash has met the increasing demands for soap. In Belgium in the early 1860s, Ernest and Alfred Solvay have derived a method of producing sodium bicarbonate from sodium chloride using ammonia, water, and carbon dioxide and the production of sodium carbonate from the heating of sodium bicarbonate. The byproduct for the first chemical reaction is ammonium chloride and the byproduct for the second chemical reaction is carbon dioxide. The demand for caustic soda also increased; the production of sodium hydroxide involves the electrolysis of sodium chloride. NaOH is used to produce paper, detergents, soap, and petroleum products. The production of chlorine through the electrolysis of brine is used to form synthetic polymers (plastics), pharmaceuticals, and pesticides. Therefore, the isolation, production, and derivation of salt, sodium hydroxide, chlorine gas, and sodium carbonate have fueled the economy and facilitated the production of a variety of products such as plastics, soap, preserved foods, and detergents. Nowadays, almost everybody has salt in their home and large quantities of salt are produced cheaply to meet the demands of society for various items.