Fuels acid-forming impurities

L.26 Sulfur is an undesirable impurity in coal and petroleum fuels. The mass percentage of sulfur in a fuel can be determined by burning the fuel in oxygen and dissolving the SO, produced in water to form aqueous sulfuric acid. In one experiment, 8.54 g of a fuel was burned, and the resulting sulfuric acid was titrated with 17.54 mL of 0.100 m NaOH(aq). (a) Determine the amount (in moles) of H2S04 that was produced, (b) What is the mass percentage of sulfur in the fuel ... 

Acid rain is caused primarily by sulfur dioxide emissions from burning fossil fuels such as coal, oil, and natural gas. Sulfur is an impurity in these fuels for example, coal typically contains 2-3% by weight sulfur.1M Other sources of sulfur include the industrial smelting of metal sulfide ores to produce the elemental metal and, in some parts of the world, volcanic eruptions. When fossils fuels are burned, sulfur is oxidized to sulfur dioxide (SO2) and trace amounts of sulfur trioxide (SC>3)J21 The release of sulfur dioxide and sulfur trioxide emissions to the atmosphere is the major source of acid rain. These gases combine with oxygen and water vapor to form a fine mist of sulfuric acid that settles on land, on vegetation, and in the ocean. 

Sulfuric acid is manufactured from elemental sulfur. Alining was the main source for this element, which was obtained from sulfide-containing ores, or in very pure form from underground deposits by the Frasch process (injection of superheated steam and air into drillings and the separation of the mixture that rises to the surface). The large-scale consumption of petroleum and natural gas has changed this scenario since sulfur occurs as an impurity in most fossil fuels and must be removed before the fuels are processed. These fuels are presently the main source of sulfur, and their relative importance tends to increase with more rigorous controls on emissions. 

In an industrial atmosphere all types of contamination by sulfur in the form of sulfur dioxide or hydrogen sulfide are important. The burning of fossil fuels generates a large amount of sulfur dioxide, which is converted to sulfuric and sulfurous acids in the presence of moisture. Combustion of these fossil fuels and hazardous waste products should produce only carbon dioxide, water vapor, and inert gas as combustion products. This is seldom the case. Depending on the impurities contained in the fossil fuel, the chemical composition of the hazardous waste materials incinerated, and the combustion conditions encountered, a multitude of other compounds may be formed. 

About 90% of U.S. energy comes from fossil fuel combustion. Fossil fuels include petroleum, natural gas, and coal. Some fossil fuels, especially coal, contain significant amounts of sulfur impurities. During combustion, these impurities react with oxygen to form SO2. In addition, during combustion of any fossil fuel, nitrogen from the air reacts with oxygen to form NO2. The SO2 and NO2 emitted from fossil fuel combustion react with water in the atmosphere to form sulfuric acid and nitric acid. 

The primary cause of acid rain is the sulfur dioxide emission from fossil-fiiel combustion. Sulfur dioxide forms because fossil fuels, especially coal, contain sulfur impurities their combustion produces sulfur dioxide (SO2) ... 

As we learned in Chapter 9, sulfur and nitrogen impurities present in fossil fuels-especially coal-form gaseous SOj and NOj during combustion. These gases combine with atmospheric water and oxygen to form sulfuric acid and nitric acid, which then fall as add rain ... 

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