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高一课本介绍,工业上常用二氧化硫来漂白纸浆、毛、丝和草帽辫等有色物质,且认为二氧化硫的漂白作用是由于它跟某些有色物质化合生成了不稳定的无色物质。而实际上,二氧化硫接触被漂白物时,是首先与水(如湿存水)反应生成亚硫酸,然后亚硫酸再跟有色物质直接结合生成无色化合物。既然真正使有色物质漂白的是亚硫酸,而不是二氧化硫,那就应当实事求是,把漂白的功劳归于亚硫酸,犹如解释氯气的漂白作用时,将功劳归于具有强氧化性的次氯酸那样。只有这样评述,才是比较合适的。
A high school textbook describes that sulfur dioxide is commonly used in industry to bleach colored materials such as pulp, wool, silk, and straw hats, and it is believed that the bleaching effect of sulfur dioxide is due to its combination with certain colored materials to create unstable, colorless materials. In fact, when SO2 comes into contact with the bleached material, it first reacts with water (such as wet water) to produce sulfurous acid, and then the sulfurous acid is directly combined with the colored material to form a colorless compound. Since it is sulfite, rather than sulfur dioxide, that really bleaches coloured substances, it should be practical and realistic to attribute the benefits of bleaching to the use of sulfurous acid as if to explain the bleaching effect of chlorine, which is attributed to the hypochloric acid with strong oxidizing properties. Only such commentary is more appropriate.