Video Transcript
Which of the following plays a very important role in the detergent industry? (A) AgCl solid, (B) MgSO4 aqueous, (C) HBr aqueous, (D) NaOH aqueous, or (E) LiOH solid.
This question refers to the industry of detergents, which are a class of substances with cleaning properties that have a hydrophobic tail and a hydrophilic head. This figure represents the general structure of a detergent, with the orange circle representing the hydrophilic head and the blue line representing the hydrophobic tail. The hydrophilic head interacts with water, while the hydrophobic tail does not. This dual behavior of a detergent molecule gives detergents their important cleaning properties, as fats, oils, stains, and other nonpolar substances can be encapsulated by detergent molecules and then washed away in water.
An example of a biodegradable and commonly used detergent is shown. This type of detergent is classified as an alkyl benzene sulfonate salt. We might also refer to it as an anionic detergent as its head contains an anion. It also contains a counterion of sodium. The industrial production of a detergent such as this one occurs in two steps. First, an alkyl benzene is reacted with hot concentrated sulfuric acid, which produces an alkyl benzene sulfonic acid and water. In step two, the alkyl benzene sulfonic acid undergoes an acid–base reaction with sodium hydroxide. We might also hear sodium hydroxide referred to as lye when in a solution or caustic soda. Like most acid–base reactions, a salt and water are produced. The salt is an alkyl benzene sulfonate salt and makes up the detergent.
So, of our answer choices, the substance with a very important role in the detergent industry is answer choice (D) NaOH aqueous.
