Question

Which of the following statement is correct? (a) Cathode is -ve terminal in both, galvanic and electrolytic cells (b) Anode is + ve terminal in both, galvanic and electrolytic cells (c) Cathode and anode are -ve terminal in electrolytic and galvanic cell. (d) Cathode and anode are +ve terminal in electrolytic and galvanic cell.

Short answer

The correct statement is (a) Cathode is -ve terminal in both, galvanic and electrolytic cells.

Step-by-step solution

Understanding Cathode and Anode in Galvanic Cells

In a galvanic cell, the cathode is the positive terminal because it is where the reduction reaction takes place, attracting cations. The anode is the negative terminal because it is where oxidation occurs, attracting anions.

Understanding Cathode and Anode in Electrolytic Cells

In an electrolytic cell, the cathode is the negative terminal since it is connected to the negative side of the external power source and is where reduction still occurs. The anode is the positive terminal because it is connected to the positive side of the power source and oxidation occurs there.

Analyzing the Options

Clearly, option (a) is correct because it accurately states that the cathode is the negative terminal in both galvanic and electrolytic cells. The other options incorrectly describe the polarity of the cathode and anode in these cells.

Key concepts

Cathode and Anode Polarity

Understanding the polarity of the cathode and anode is crucial when studying electrochemical cells, as it directly impacts the flow of electrons and the direction of the chemical reactions. In a galvanic cell, the cathode is positively charged. This happens because galvanic cells spontaneously convert chemical energy into electrical energy, driving electrons from the anode to the cathode.

In contrast, an electrolytic cell requires an external power source to drive the chemical reaction, which is not spontaneous. Here, the cathode is negatively charged because it is connected to the negative side of the power source. This difference in polarity is integral to how these two types of cells operate and is why they are utilized in varying applications.

Galvanic Cell Reduction

Reduction processes are at the heart of galvanic cells. The term 'reduction' refers to the gain of electrons by an element or compound. At the cathode of the galvanic cell, the cations in the solution gain electrons and are reduced. This is a spontaneous process and is a part of the overall redox reaction that allows the galvanic cell to produce electrical energy.

Understanding reduction is essential for comprehending why the cathode is the positive terminal in galvanic cells. It attracts the positively charged cations because they are 'reduced' or gain electrons, there. The entire process hinges on the natural tendency for the system to move towards a lower energy state, which is what drives the generation of electrical current.

Electrolytic Cell Oxidation

In an electrolytic cell, oxidation occurs at the anode, which is notably the positive terminal. Oxidation is the loss of electrons, and this process requires energy input from an external source to occur since it is non-spontaneous. Anions are attracted to the anode, where they lose electrons and are oxidized.

The concept of oxidation in electrolytic cells is fundamental for applications such as electroplating or electrolysis, where materials are deposited or chemical compounds are decomposed. By understanding that electrons flow from the negative cathode to the positive anode, driven by the external power source, students can better grasp the underlying chemical processes at work in electrolytic cells.