Final answer:
Concentrated sulfuric acid is a laboratory reagent that dehydrates ethanol, forming ethylene and water through the removal of an OH group and a hydrogen atom from the ethanol molecules.
Step-by-step explanation:
One laboratory reagent used to dehydrate ethanol is concentrated sulfuric acid. When two molecules of ethanol are dehydrated in the presence of concentrated sulfuric acid at 180 degrees celsius, the ethanol undergoes a dehydration reaction. This process forms ethylene and water. The structural formula of ethanol changes such that the OH group from the alcohol carbon atom and a hydrogen atom from an adjacent carbon atom are removed, resulting in the formation of the alkene and a water molecule as a side product. Depending on conditions, this reaction can produce either alkenes or ethers.