Oxidation & Reduction in Terms of Electrons Flashcards

All 8 cards in this deck

Define oxidation and reduction in terms of electrons.

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

In a displacement reaction between a metal and a metal ion in solution, which species is oxidised?

The metal atom, because it loses electrons to form its positive ion.
e.g. $\mathrm{Mg} \rightarrow \mathrm{Mg^{2+}} + 2e^-$

What is a redox reaction?

A reaction in which oxidation and reduction happen at the same time (one species loses electrons as another gains them).

What are the steps to write the ionic equation for a displacement reaction?

e.g. zinc added to copper sulfate solution

1. Write the full equation: $\mathrm{Zn} + \mathrm{CuSO_4} \rightarrow \mathrm{ZnSO_4} + \mathrm{Cu}$
2. Cross out the spectator ion ($\mathrm{SO_4^{2-}}$, unchanged on both sides).
3. Write what is left with state symbols: $\mathrm{Zn(s)} + \mathrm{Cu^{2+}(aq)} \rightarrow \mathrm{Zn^{2+}(aq)} + \mathrm{Cu(s)}$

In $\mathrm{Mg(s)} + \mathrm{Zn^{2+}(aq)} \rightarrow \mathrm{Mg^{2+}(aq)} + \mathrm{Zn(s)}$, which species is oxidised and which is reduced?

Magnesium atoms are oxidised (lose electrons); zinc ions are reduced (gain electrons).

True or false? Oxidation can only happen if oxygen is involved.

False. Oxidation is the loss of electrons, which can happen with no oxygen present.

What is the half equation for the oxidation of zinc atoms?

$\mathrm{Zn} \rightarrow \mathrm{Zn^{2+}} + 2e^-$

When copper is added to silver nitrate solution, what two observations show a displacement reaction has happened?

Pale grey crystals of silver form and the solution turns blue (copper ions).