3.2.2 Displacement Reactions

• Redox reactions involve the transfer of electrons
• Oxidation involves the loss of electrons.
• Reduction is the gain of electrons
• The oxidation state of a species decreases during reduction.
• Summarize the differences between oxidation and reduction.

  1️⃣ Electron Transfer: Oxidation involves loss, reduction involves gain

  2️⃣ Oxidation State: Oxidation increases, reduction decreases

  3️⃣ Species Involved: Oxidation donates, reduction accepts electrons
• In the reaction between zinc and copper(II) ions, zinc is oxidized
• Why is understanding redox reactions crucial?

  Involved in biological and industrial processes
• Redox reactions are also known as oxidation-reduction reactions.
• Redox reactions are vital in both biological and industrial
• Oxidizing agents accept electrons and cause reduction.
• Reducing agents donate electrons and cause reduction
• The oxidation state of a reducing agent increases during a redox reaction.
• In the reaction between magnesium and oxygen, oxygen acts as the oxidizing agent.
• Displacement reactions are a type of redox reaction.
• The reactivity series lists elements in order of their ability to displace others from compounds
• Order the following elements based on their reactivity from highest to lowest:

  1️⃣ Potassium

  2️⃣ Sodium

  3️⃣ Magnesium

  4️⃣ Zinc

  5️⃣ Iron

  6️⃣ Copper

  7️⃣ Silver
• What happens when zinc is added to a solution of copper(II) sulfate?

  Zinc displaces copper
• In the reaction between zinc and copper(II) sulfate, zinc is oxidized to $\text{Zn}^{2 + }$.
• What is oxidation in a redox reaction?

  Loss of electrons
• In a redox reaction, the oxidation state of a species undergoing oxidation increases
• In a redox reaction, reduction involves the gain of electrons.
• In the reaction \text{Zn} + \text{Cu}^{2 + } \rightarrow \text{Zn}^{2 + } + \text{Cu}</latex>, which species is oxidized?

  Zinc
• In the reaction $\text{Zn} +$$\text{Cu}^{2 + } \rightarrow \text{Zn}^{2 + } +$$\text{Cu}$, copper(II) ions are reduced
• What is the role of a reducing agent in a redox reaction?

  Donates electrons
• In a redox reaction, the oxidation state of a reducing agent increases.
• In the reaction 2\text{Mg} + \text{O}_{2} \rightarrow 2\text{MgO}</latex>, oxygen is the oxidizing agent.
• Order the following elements based on their reactivity in displacement reactions:

  1️⃣ Potassium

  2️⃣ Sodium

  3️⃣ Magnesium

  4️⃣ Zinc

  5️⃣ Iron

  6️⃣ Copper

  7️⃣ Silver
• Which metal is least reactive in the reactivity series?

  Silver
• In the reaction $\text{Zn} +$$\text{CuSO}_{4} \rightarrow \text{ZnSO}_{4} +$$\text{Cu}$, zinc displaces copper from copper sulfate.
• In the reaction \text{Zn} + \text{CuSO}_{4} \rightarrow \text{ZnSO}_{4} + \text{Cu}</latex>, zinc is oxidized to $\text{Zn}^{2 + }$.
• What governs single displacement reactions?

  Reactivity series
• What does an oxidizing agent do in a single displacement reaction?

  Accepts electrons
• In the reaction $\text{Zn} +$$\text{CuSO}_{4} \rightarrow \text{ZnSO}_{4} +$$\text{Cu}$, copper(II) ions are reduced.
• Unlike single displacement reactions, double displacement reactions do not involve changes in oxidation states.
• In the reaction \text{AgNO}_{3}(aq) + \text{NaCl}(aq) \rightarrow \text{AgCl}(s) + \text{NaNO}_{3}(aq)</latex>, what type of precipitate is formed?

  Silver chloride
• In a double displacement reaction, ions exchange to form new compounds without changes in oxidation states.
• How does a single displacement reaction differ from a double displacement reaction?

  Oxidation states change
• To balance redox equations, the first step is to write half-equations for oxidation and reduction.
• Steps to balance redox equations using half-equations:

  1️⃣ Write half-equations

  2️⃣ Balance atoms

  3️⃣ Balance charge

  4️⃣ Equalize electrons

  5️⃣ Combine half-equations

  6️⃣ Verify balance
• What is the balanced redox equation for the reaction between zinc and copper(II) ions?

  $\text{Zn} +$$\text{Cu}^{2 + } \rightarrow \text{Zn}^{2 + } +$$\text{Cu}$