Metal Displacement Reactions & Redox Flashcards

All 5 cards in this deck

What would you see when excess zinc is added to blue copper sulfate solution?

A (red-)brown/orange/pink solid forms, some grey/silver solid remains, and the blue solution becomes colourless.

When will a metal displace another metal from its salt solution?

When the added metal is more reactive than the metal in the salt.

e.g. zinc displaces copper from copper sulfate.

In redox, what happens to electrons in oxidation and in reduction?

Oxidation is the loss of electrons; reduction is the gain of electrons.

What are the steps to identify what is oxidised and reduced in a displacement reaction?

e.g. $\mathrm{Zn + CuSO_4 \rightarrow ZnSO_4 + Cu}$

1. Write the half equation for the metal: $\mathrm{Zn \rightarrow Zn^{2+} + 2e^-}$, so zinc is oxidised (loses electrons).
2. Write the half equation for the metal ion: $\mathrm{Cu^{2+} + 2e^- \rightarrow Cu}$, so copper ions are reduced (gain electrons).

True or false? When copper oxide, CuO, reacts with sulfuric acid to form copper sulfate, the copper is reduced.

False. The copper ions are neither oxidised nor reduced — $\mathrm{Cu^{2+}}$ is present at the start and end.