Question

this passage describes a chemical reaction. read the passage. then, answer the question below.

over 200,000 miles of train tracks have been built in the united states since the early 1800s. workers who build new train tracks often use a process called thermite welding to connect short pieces of metal track. this type of welding uses thermite powder, which is a mixture of aluminum metal (al) and ferric oxide (fe₂o₃). a worker places the powder between two pieces of track and burns it to form aluminum oxide (al₂o₃) and iron metal (fe). this process releases an enormous amount of energy that melts the two pieces of track together.

in the chemical reaction described in the passage, which of the following are reactants?
select all that apply.

iron (fe)
ferric oxide (fe₂o₃)
aluminum (al)
aluminum oxide (al₂o₃)

Explanation:

To determine the reactants, we recall that reactants are the substances that undergo a chemical change (are consumed) to form products. From the passage, the thermite powder is a mixture of aluminum metal (Al) and ferric oxide ($\ce{Fe_{2}O_{3}}$), and these are burned to form aluminum oxide ($\ce{Al_{2}O_{3}}$) and iron metal (Fe). So, Al and $\ce{Fe_{2}O_{3}}$ are the reactants, while $\ce{Al_{2}O_{3}}$ and Fe are the products. The initial selections included incorrect choices (Fe and $\ce{Al_{2}O_{3}}$ were wrongly marked as reactants). The correct reactants are the starting materials: aluminum (Al) and ferric oxide ($\ce{Fe_{2}O_{3}}$).

Answer:

• ferric oxide ($\ce{Fe_{2}O_{3}}$)
• aluminum (Al)