Question

In the single replacement reaction between Zn and CuSO₄, how did we know when enough Zn is added to complete the reaction?

a) No color change was observed
b) The solution became a darker blue color
c) The blue color of the solution disappeared

Answer 1

In a single replacement reaction between Zn and CuSO4, one can determine that the reaction is complete when the blue color of the solution disappears, indicating all Cu^2+ ions have been reduced. Option C

Step-by-step explanation:

In the context of Direct Redox Reactions, the single replacement reaction between Zn and CuSO4 can be monitored by observing the color change in the solution. During the reaction, Zn(s) reacts with CuSO4(aq) to form Cu(s) and ZnSO4(aq).

The blue color of the copper(II) sulfate solution is due to the Cu2+ ions in the solution. As zinc metal reacts with CuSO4, zinc goes into solution as Zn2+ ions, and the Cu2+ ions get reduced to elemental copper, thus depositing on the zinc strip.

The reaction continues until all the Cu2+ ions in solution have been reduced, which is visually indicated when the blue color of the solution disappears because there are no more Cu2+ ions to impart the blue color. This color change signifies that the reaction has reached completion. Option C