Chemistry_Grade_10-12 (1).pdf

233 the chloralkali industry the chlorine alkali

Info icon This preview shows pages 456–458. Sign up to view the full content.

23.3 The Chloralkali Industry The chlorine-alkali (chloralkali) industry is an important part of the chemical industry, and pro- duces chlorine and sodium hydroxide through the electrolysis of salt (NaCl). The main raw material is brine which is a saturated solution of sodium chloride (NaCl) that is obtained from natural salt deposits. The products of this industry have a number of important uses. Chlorine is used to purify water, and is used as a disinfectant. It is also used in the manufacture of many every-day items such as hypochlorous acid, which is used to kill bacteria in drinking water. Chlorine is also used in paper production, antiseptics, food, insecticides, paints, petroleum products, plastics (such as polyvinyl chloride or PVC), medicines, textiles, solvents, and many other consumer products. Many chemical products such as chloroform and carbon tetrachloride also contain chlorine. Sodium hydroxide (also known as ’caustic soda’) has a number of uses, which include making soap and other cleaning agents, purifying bauxite (the ore of aluminium), making paper and making rayon (artificial silk). 23.3.1 The Industrial Production of Chlorine and Sodium Hydroxide Chlorine and sodium hydroxide can be produced through a number of different reactions. How- ever, one of the problems is that when chlorine and sodium hydroxide are produced together, the chlorine combines with the sodium hydroxide to form chlorate ( ClO ) and chloride ( Cl ) ions. This produces sodium chlorate, NaClO, a component of household bleach. To overcome this problem the chlorine and sodium hydroxide must be separated from each other so that they don’t react. There are three industrial processes that have been designed to overcome this problem, and to produce chlorine and sodium hydroxide. All three methods involve electrolytic cells (chapter 17). 442
Image of page 456

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

CHAPTER 23. THE CHEMICAL INDUSTRY - GRADE 12 23.3 Important: Electrolytic cells Electrolytic cells are used to split up or loosen ions. They are made up of an electrolyte and two electrodes, the cathode and the anode . An electrolytic cell is activated by applying an external electrical current. This creates an electrical potential across the cathode and anode, and forces a chemical reaction to take place in the electrolyte. Cations flow towards the cathode and are reduced. Anions flow to the anode and are oxidised. Two new products are formed, one product at the cathode and one at the anode. 1. The Mercury Cell In the mercury-cell (figure 23.4), brine passes through a chamber which has a carbon electrode (the anode) suspended from the top. Mercury flows along the floor of this chamber and acts as the cathode. When an electric current is applied to the circuit, chloride ions in the electrolyte are oxidised to form chlorine gas.
Image of page 457
Image of page 458
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern