Caustic soda Sodium hydroxide

Sodium fluoride is normally manufactured by the reaction of hydrofluoric acid and soda ash (sodium carbonate), or caustic soda (sodium hydroxide). Control of pH is essential and proper agitation necessary to obtain the desired crystal size. The crystals are centrifuged, dried, sized, and packaged. Reactors are usually constmcted of carbon brick and lead-lined steel, with process lines of stainless, plastic or plastic-lined steel diaphragm, plug cock, or butterfly valves are preferred. 

Chemical Reactivity - Reactivity with Water A slow, non-hazardous reaction occurs, forming propanolamine Reactivity with Common Materials No reactions Stability During Transport The product is stable if it is kept in contact with solid caustic soda (sodium hydroxide) Neutralizing Agents for Acids and Caustics Dilute with water and rinse with vinegar solution Polymerization This material will polymerize explosively when in contact with any acid Inhibitor of Potymerization Solid sodium hydroxide (caustic soda). 

Washing soda (sodium carbonate) and caustic soda (sodium hydroxide)... 

Both hot and cold processes are employed, although the hot process, which takes place at or above 212 °F (100 °C), is usually preferred for boiler FW applications, because it produces water of lower hardness levels and usually a lower silica content as well. Also, less lime is needed because the carbon dioxide with which it would normally react is driven off at the higher temperatures. Sometimes caustic soda (sodium hydroxide) is used in place of soda, depending on the alkalinity of the water and the chemical costs however, irrespective of the process or chemicals used, the major precipitants are always calcium carbonate and magnesium hydroxide. 

Lime is employed in the krafl pulping process to be discussed in detail in Chapter 22, Section 3.1. Most of it is recycled. Without this recycling the pulp and paper industry would be the largest lime user. The main reaction of lime in the krafl process is for the purpose of regenerating caustic soda (sodium hydroxide). 

By the beginning of the nineteenth century, caustic soda (sodium hydroxide) and caustic potash (potassium hydroxide) had come to be very widely used in chemical laboratories. Both substances were thought to be elements no one had ever broken them down into their chemical components. Nevertheless, Davy began to wonder if they might not turn out to be compounds after all, so he decided to subject them to electrolysis to see what happened. Realizing that the more powerful the batteries used, the better the chances of success, he had an assistant connect together all the batteries that the institution possessed. He then dissolved some caustic potash in water and passed an electrical current through the solution. 

Just as there are strong and weak acids, so too there are strong and weak bases. One very common strong base is caustic soda - sodium hydroxide. This has a powerfully corrosive effect on grease and animal matter, and is often used in cleaning agents for ovens and drains. 

The most important industrial alkalis are the weak alkali ammonia (Section 9.3), caustic soda (sodium hydroxide), and lime (calcium oxide).1-6 For many industrial and agricultural purposes, the most economical source of alkali is lime, which is used in steelmaking and other metallurgical operations ( 45% of U.S. production of lime), in control of air pollution from smokestack gases (Chapter 8), in water and sewage treatment (Sections 9.6 and 14.5), in pulp and paper production (Section 10.4), in reduction of soil acidity, in cement and concrete manufacture (indirectly, as discussed later), and in many chemical processes such as paper making (Section 10.4). In short, lime is one of the most important of all chemical commodities. 

Annual production of caustic soda (sodium hydroxide) in the United States is about 10 million metric tons, of which 50% is consumed by the chemical industry and a further 20% by pulp and paper plants. Sodium hydroxide is made by electrolyzing strong brine, that is, decomposing it by passing an electric current.1 6 Saturated brine contains about 360 g or 6.2 mol NaCl per kilogram water. 

The electrolytic cell shown in Figure 2 is the industrial chloralkali cell in which brine (an aqueous sodium chloride solution) is electrolytically converted to chlorine and caustic soda (sodium hydroxide, NaOH). The external power source supplies electric energy to drive the overall reaction. 

The electrolysis of brine is carried out on a huge scale for the industrial production of chlorine and caustic soda (sodium hydroxide). Because the reduction potential of Na+ is much higher than that of water, the latter substance undergoes decomposition at the cathode, yielding hydrogen gas and OH-. 

The chemical category of inorganic salts encompasses many substances that dissociate completely in water, but only one salt, sodium chloride, is referred to by the common name, salt. Sodium chloride is ubiquitous in both its occurrence and its many uses. To date, there are over 14,000 uses for salt.1 Salt is used as a feedstock for many chemicals including chlorine, caustic soda (sodium hydroxide), synthetic soda ash (sodium carbonate), sodium chlorate, sodium sulfate, and metallic sodium. By indirect methods, sodium chloride is also used to produce hydrochloric acid and many other sodium salts. In its natural mineral form, salt may take on some color from some of the trace elements and other salts present, however, pure sodium chloride is a white to colorless crystalline substance, fairly soluble in water.2 Also known as halite, the substance... 

Chlorine and caustic soda (sodium hydroxide) are among the top ten commodity chemicals produced in the world. In 2004, North America produced about 29 million tons of chlorine and caustic soda.18 Figure 26.5 shows the global production of chlorine by region in 2004. 

The nature of a chemical will, obviously, affect its disposition and its effects on the body (the nature of a chemical can be described in terms of its so-called physico-chemical characteristics). These various characteristics wiU affect both the site of exposure and the consequences of the exposure. A chemical may be a solid, a liquid, or a gas. A solid may be in solution in water, for example sugar in a cup of tea, or in another solvent, for example alcohol, which is used to dissolve the fragrances in perfume. Liquids may be volatile such as petrol or white spirit. A solid may be in the form of lumps, crystals (for example, salt), or very small particles. Furthermore, the chemical could be irritant or corrosive, such as an acid like battery acid (hydrochloric acid) or kettle descaler (formic acid), or an alkali like caustic soda (sodium hydroxide), which is found in oven cleaners. The latter may not be weU absorbed from any of the three sites of exposure but will stiU cause damage to the tissues with which they come into contact. Substances that are not at all soluble in fat wiU not be well absorbed, nor wiU substances that are very soluble in fat but not soluble in water. However, sufficient of the chemical may be absorbed for it to be toxic even if it is a very small amount. Substances that are soluble in fat wiU also be more readily distributed around the body and metabolized. 

Exposure to a chemical can cause damage at the point or site of exposure if the substance is reactive, irritant, corrosive, or caustic. Thus substances such as kettle descaler (formic acid), battery acid (sulphuric acid), caustic soda (sodium hydroxide), and bleach (sodium hypochlorite/hypochlorous acid) can cause serious, and maybe permanent, damage to the skin, the eyes or the oesophagus, and stomach if they come into contact with these parts of the body. Unfortunately, people sometimes attempt suicide by swallowing such substances for example, drinking kettle descaler or bleach causes serious damage to the lining of the gut (see case notes, p- 193). 

Sodium hydroxide caustic soda), NaOH, is a white hygroscopic (water-attracting) solid, which dissolves readily in water. Its solutions have a smooth, soapy feeling, and are very corrosive to the skin (this is the meaning of caustic in the name caustic soda). Sodium hydroxide is made either by the electrolysis of sodium chloride (Chap. 

A 10.0 moIe% aqueous sulfuric acid solution (SG = 1.27) is to be titrated to neutrality at 25°C with a 3.00-molar caustic soda (sodium hydroxide) solution (SG = 1.13) ... 

Step 8. The waste liquor from the reactor centrifuge flows to a waste liquor neutralizer, where the HCl is neutralized with a caustic soda (sodium hydroxide) solution ... 

LYE sometimes refers to solutions of soda ash or potash. It is also used for solutions of CAUSTIC SODA sodium hydroxide) and CAUSTIC POTASH (potassium hydroxide), prepared by mixing milk of lime with soda ash or potash. This mixing produces a solution of caustic soda, or caustic potash, and a limestone precipitate. A medieval recipe for caustic soda crystals calls for 1 part each of slaked lime and soda ash with 7 parts water, boiled until the volume is halved, filtered and decanted 10 times then evapouiated. 

What became known as the Leblanc process was actually several interrelated processes. Salt was first reacted with sulphuric acid in a cast-iron pan, then in a reverberator furnace (in which heat was apphed from a flame blown from a separate chamber, not in direct contact with the salt), to produce saltcake (sodium sulphate), with hydrochloric acid released as a waste gas. Saltcake was used to make sodium carbonate, or roasted with limestone (calcium carbonate) and coal or coke to produce black ash. This mixture of sodium carbonate, calcium sulphide, sodium sulphide, hme, salt, carbon, and ash could be treated further with hot water to produce impure sodium carbonate in solution, evaporated into soda crystals (washing soda), or heated to yield anhydrous sodium carbonate. The latter, in turn, could be reacted with lime to made caustic soda (sodium hydroxide), the strongest commercial alkali then available. 

CHEMICAL PROPERTIES extremely stable resists hydrolysis reacts with chemi-cally-active metals such as lithium, beryllium, and barium reaction with strong oxidizers, caustic soda, sodium hydroxide, and potash FP (NA) LFL/UFL (NA) AT (NA). 

INTRODUCE ENOUGH WATER INTO THE UNIT TO COVER ALL SOLVENT to a depth of 2 to 4 in. (5 to 10 cm). Add a water solution of soda ash (sodium carbonate) at a concentration of about 1/4 to V2 Ib/gal (30 to 60 kg/m ) of water. This will help neutralize the acid decomposition and will facilitate cleaning the machine. DO NOT USE CAUSTIC SODA (sodium hydroxide) OR CAUSTIC POTASH (potassium hydroxide) because an explosive product may result. 

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