10 Questions
What is the purpose of the salt bridge in the cell?
To complete the circuit
In the given reactions, what reduces copper ions?
Cu(s)
What is the direction of current in the cell compared to the direction of electron flow?
Opposite
What does an oxidising agent do in a chemical reaction?
Accepts electrons
Which element is the strongest reducing agent based on the given table?
Al3+
Which substance is most likely to release electrons based on its reduction potential?
$2H^+ + 2e^-$
Which process involves Cl2 getting reduced?
$Cl2(g) + 2e^-$
What happens to Zn in the given text?
Gets oxidized at the anode
$MnO_4^- + 8H^+ + 5e^- ightarrow$ What kind of reaction is this?
Reduction
In the given reactions, what happens to Cu(s)?
Copper ions reduction
Study Notes
Redox Reactions
- Examples of redox reactions include H2(s) + Cl2(g) ® 2HCl(g) and CH4(g) + 4Cl2(g) ® CCl4(l) + 4HCl(g).
- In redox reactions, it is assumed that there is a complete transfer of electrons from a less electronegative atom to a more electronegative atom.
Oxidation Number
- Oxidation number is a method to keep track of electron shifts in chemical reactions involving formation of covalent compounds.
- In this method, it is assumed that there is a complete transfer of electron from a less electronegative atom to a more electronegative atom.
- Electrons produced at the anode due to oxidation of Zn travel through the external circuit to the cathode where these reduce the copper ions.
Galvanic Cells
- Galvanic cells are a class of cells in which chemical reactions become the source of electrical energy.
- These cells are designed based on the competition for electrons between various metals.
Electron Transfer
- A less obvious example of electron transfer is realized when hydrogen combines with oxygen to form water by the reaction: 2H2(g) + O2 (g) ® 2H2O (l).
- It is assumed that there is an electron transfer from H to O and consequently H2 is oxidised and O2 is reduced.
Metal Activity Series
- The metal activity series is a list of metals and their ions based on their tendency to release electrons.
- The electron releasing tendency of the metals is in the order: Zn>Cu>Ag.
Standard Electrode Potentials
- The standard electrode potentials of various ions are listed in Table 8.1.
- The table shows the reduction potentials of different metals and ions.
Test your knowledge on chemical reactions and the oxidation number method for tracking electron shifts. This quiz covers examples and principles of balancing chemical equations based on electron transfer.
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