The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z. Neutron number plus atomic number equals atomic mass number: N+Z=A. The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. Mass numbers of typical isotopes of Chlorine are 35 37. The Manufacture of Chlorine.Neutron Number and Mass Number of Chlorine When KCl is used, the resulting products are chlorine, potassium hydroxide (KOH), and hydrogen gas.Ĭitation: Clark, J.

How is chlorine made from other compounds? Sometimes, the salt used is not sodium chloride, but rather potassium chloride (KCl). Producing chlorine from potassium chloride The sodium hydroxide is concentrated up to 50%. This makes the solution more concentrated and the salt precipitates out of the solution and is recovered to make more brine. The mixed sodium hydroxide and brine solution is heated to evaporate water. Sodium hydroxide often contains leftover salt in the solution. By cooling the gas, the chlorine turns into a liquid, while the oxygen remains a gas, thus enabling its separation. Depending on the specific conditions of the electrolytic cell, varying concentrations of oxygen, salt, and water are present in the final products.Ĭhlorine gas is contaminated with oxygen that must be removed. The electrolysis of brine does not completely convert the salt water to the final products. The sodium hydroxide solution is then removed from the electrolytic cell. The chemical equation is:Īt this point, there is a buildup of negative hydroxide ions (OH –) that bond with positive sodium ions (Na +) to form sodium hydroxide in solution. At the cathode, positive hydrogen ions gain electrons (reduction) and instantaneously covalently bond with itself to form H 2 gas that is removed from the electrolytic cell. Hydrogen ions and hydroxide ions are present due to the natural state of equilibrium of water. The negative charge of the cathode attracts the positively charged sodium and hydrogen ions (often referred to as protons). Instantaneously, chlorine covalently bonds to itself to make Cl 2 gas that is removed from the electrolytic cell. Upon contact with the anode, the chloride ions lose two electrons (oxidization). The positive charge of the anode attracts the negatively charged chloride ions. The selectivity of the membrane keeps the final products physically separated. Between the electrodes is a selectively-permeable membrane that allows positive ions to pass – hydrogen (H +) and sodium (Na +). The electrodes are submerged in the liquid brine. The anode has a positive charge, the cathode has a negative charge, and electrons flow from the anode to the cathode. NaCl + H 2O + electricity → NaOH + Cl 2(g) + H 2(g)Įlectricity is applied to the solution through two electrodes in the cell, the anode and cathode. The electricity rearranges the elements present in the brine, NaCl and H 2O, and creates Cl 2, NaOH, and H 2.

This reaction occurs when electricity is applied to brine. The chlorine manufacturing process, which includes industrial preparation and production of chlorine, sodium hydroxide, and hydrogen, involves a common chemical reaction known as electrolysis. To do so, brine is filtered by ion-exchange membranes that allow only the sodium and chloride ions, along with water, to pass through the membrane. However, the brine must be purified to remove potential contaminants, such as magnesium, calcium, and iron that have the potential to disrupt the electrolysis process described below. Otherwise, dry salt is transported by rail or barge to a manufacturing facility and then dissolved in water to make brine. The salt can be dissolved in water to create a brine solution, then transported by pipeline to the facility. Once the salt is mined, it must be transported to an industrial chlorine manufacturing facility, commonly called a chlor-alkali manufacturing facility.

Chlorine atom