Step 1: Analyze the experimental setup.
The diagram shows hydrogen gas being generated from the reaction of zinc granules with dilute hydrochloric acid. This gas then passes through a U-tube containing "Substance Z" before reacting with copper(II) oxide. The purpose of the U-tube containing Substance Z in this setup is to remove moisture from the hydrogen gas, as hydrogen produced from an aqueous solution will be wet.
Step 2: Identify common drying agents for hydrogen gas.
Common drying agents suitable for hydrogen gas include concentrated sulfuric acid, anhydrous calcium chloride, and silica gel. Since Substance Z is placed in a U-tube, a solid drying agent is typically used.
Step 3: Determine the most appropriate substance for Z.
Anhydrous calcium chloride is a commonly used solid drying agent for gases like hydrogen, often packed in U-tubes.
Substance Z: Anhydrous calcium chloride