Q. What is a reducing agent of the reaction Cu2+ Zn → Cu Zn2+

In the reaction Cu2+ + Zn → Cu + Zn2+, zinc (Zn) is the reducing agent. The reducing agent is the substance that causes reduction in another species by donating electrons—and in doing so, the reducing agent itself becomes oxidized. In this case, zinc metal donates electrons to copper ions, enabling the Cu2+ ions to be reduced to neutral copper metal (Cu), while the zinc itself is oxidized from Zn0 to Zn2+.

Understanding reducing agents requires recognizing that they are electron donors and always undergo oxidation themselves during the reaction. Zinc serves this role because it has a greater tendency to lose electrons than copper does—this difference in reactivity is quantified in the activity series and electrochemical potential tables. The reaction is thermodynamically favorable because zinc is more reactive (more easily oxidized) than copper, which is why zinc can "push" electrons onto copper ions. This type of redox reaction has practical applications in galvanizing (coating iron with zinc for corrosion protection) and in voltaic cells where the electron flow from zinc to copper can generate electrical current. To identify the reducing agent in any redox reaction, look for the species that loses electrons or increases in oxidation state—that substance is reducing the other species by giving it electrons.