What do you mean by electrochemical equivalence Class 12?
2 Answers
Electrochemical equivalence is a fundamental concept in electrochemistry that relates to the amount of substance transformed during an electrochemical reaction. It helps us understand how electrical energy can be converted into chemical energy and vice versa. Here’s a detailed explanation tailored for a Class 12 level:
### Definition
Electrochemical equivalence refers to the mass of a substance that is deposited or dissolved at an electrode during electrolysis when a certain amount of electric charge passes through the electrolyte. It is expressed in terms of the mass of the substance (in grams) that corresponds to one coulomb of electric charge.
### Key Concepts
1. **Faraday's Laws of Electrolysis**:
- **First Law**: The mass of a substance deposited at an electrode is directly proportional to the quantity of electricity (in coulombs) passed through the electrolyte. This can be expressed mathematically as:
\[
m \propto Q
\]
where \( m \) is the mass of the substance, and \( Q \) is the charge.
- **Second Law**: The mass of different substances deposited by the same quantity of electricity is proportional to their equivalent weights. This means that different substances will have different amounts of mass deposited depending on their chemical properties.
2. **Electrochemical Equivalent (E)**:
- The electrochemical equivalent of a substance is defined as the mass of that substance deposited or dissolved by one coulomb of electric charge. It can be calculated using the formula:
\[
E = \frac{M}{nF}
\]
where:
- \( E \) = electrochemical equivalent (in grams per coulomb)
- \( M \) = molar mass of the substance (in grams per mole)
- \( n \) = number of electrons transferred in the half-reaction (valency)
- \( F \) = Faraday's constant (approximately \( 96485 \, \text{C/mol} \))
### Example
Consider the electrolysis of copper(II) sulfate (\( \text{CuSO}_4 \)) solution:
- When electricity is passed through the solution, copper ions (\( \text{Cu}^{2+} \)) are reduced to form copper metal at the cathode:
\[
\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}
\]
- For copper, the molar mass \( M \) is approximately \( 63.5 \, \text{g/mol} \) and \( n = 2 \) (because two electrons are needed to reduce one copper ion). Thus, the electrochemical equivalent \( E \) can be calculated as:
\[
E = \frac{63.5 \, \text{g/mol}}{2 \times 96485 \, \text{C/mol}} \approx 0.000329 \, \text{g/C}
\]
This means that when one coulomb of charge passes through the solution, approximately \( 0.000329 \, \text{g} \) of copper will be deposited.
### Applications
Understanding electrochemical equivalence is crucial for various applications, including:
- **Electroplating**: In processes like electroplating, knowing the electrochemical equivalence helps in determining how much metal will be deposited in a given time.
- **Batteries and Fuel Cells**: Electrochemical equivalence principles apply to the operation of batteries, helping to calculate energy storage and conversion efficiency.
- **Corrosion Studies**: It aids in understanding and predicting corrosion rates of metals in different environments.
### Conclusion
Electrochemical equivalence is a vital concept that connects the physical properties of substances with their behavior in electrochemical reactions. It is rooted in Faraday’s laws and has practical implications in various fields, from manufacturing to energy technology. Understanding it provides insights into how electrical energy can be harnessed and manipulated through chemical processes.
### Definition
Electrochemical equivalence refers to the mass of a substance that is deposited or dissolved at an electrode during electrolysis when a certain amount of electric charge passes through the electrolyte. It is expressed in terms of the mass of the substance (in grams) that corresponds to one coulomb of electric charge.
### Key Concepts
1. **Faraday's Laws of Electrolysis**:
- **First Law**: The mass of a substance deposited at an electrode is directly proportional to the quantity of electricity (in coulombs) passed through the electrolyte. This can be expressed mathematically as:
\[
m \propto Q
\]
where \( m \) is the mass of the substance, and \( Q \) is the charge.
- **Second Law**: The mass of different substances deposited by the same quantity of electricity is proportional to their equivalent weights. This means that different substances will have different amounts of mass deposited depending on their chemical properties.
2. **Electrochemical Equivalent (E)**:
- The electrochemical equivalent of a substance is defined as the mass of that substance deposited or dissolved by one coulomb of electric charge. It can be calculated using the formula:
\[
E = \frac{M}{nF}
\]
where:
- \( E \) = electrochemical equivalent (in grams per coulomb)
- \( M \) = molar mass of the substance (in grams per mole)
- \( n \) = number of electrons transferred in the half-reaction (valency)
- \( F \) = Faraday's constant (approximately \( 96485 \, \text{C/mol} \))
### Example
Consider the electrolysis of copper(II) sulfate (\( \text{CuSO}_4 \)) solution:
- When electricity is passed through the solution, copper ions (\( \text{Cu}^{2+} \)) are reduced to form copper metal at the cathode:
\[
\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}
\]
- For copper, the molar mass \( M \) is approximately \( 63.5 \, \text{g/mol} \) and \( n = 2 \) (because two electrons are needed to reduce one copper ion). Thus, the electrochemical equivalent \( E \) can be calculated as:
\[
E = \frac{63.5 \, \text{g/mol}}{2 \times 96485 \, \text{C/mol}} \approx 0.000329 \, \text{g/C}
\]
This means that when one coulomb of charge passes through the solution, approximately \( 0.000329 \, \text{g} \) of copper will be deposited.
### Applications
Understanding electrochemical equivalence is crucial for various applications, including:
- **Electroplating**: In processes like electroplating, knowing the electrochemical equivalence helps in determining how much metal will be deposited in a given time.
- **Batteries and Fuel Cells**: Electrochemical equivalence principles apply to the operation of batteries, helping to calculate energy storage and conversion efficiency.
- **Corrosion Studies**: It aids in understanding and predicting corrosion rates of metals in different environments.
### Conclusion
Electrochemical equivalence is a vital concept that connects the physical properties of substances with their behavior in electrochemical reactions. It is rooted in Faraday’s laws and has practical implications in various fields, from manufacturing to energy technology. Understanding it provides insights into how electrical energy can be harnessed and manipulated through chemical processes.
In Class 12 chemistry, **electrochemical equivalence** is a concept used in electrochemistry to describe the amount of a substance that is deposited or dissolved during an electrochemical reaction when a certain amount of charge passes through the system.
### Electrochemical Equivalence
The term **electrochemical equivalent** (ECE) refers to the mass of a substance that is deposited (or dissolved) at an electrode when 1 coulomb of electric charge is passed through an electrolyte solution.
This concept is based on **Faraday's Laws of Electrolysis**. According to Faraday's laws:
1. **First Law of Electrolysis**:
The mass of a substance deposited or liberated at an electrode is directly proportional to the amount of electric charge (current × time) passed through the electrolyte.
\[
m \propto Q
\]
where \(m\) is the mass of the substance, and \(Q\) is the total electric charge (in coulombs).
2. **Second Law of Electrolysis**:
The masses of different substances deposited or liberated by the same amount of electric charge are proportional to their chemical equivalents or equivalent weights.
\[
m \propto \frac{E}{F}
\]
where \(E\) is the equivalent weight of the substance, and \(F\) is Faraday's constant (approximately 96,485 C/mol).
### Definition of Electrochemical Equivalent
The **electrochemical equivalent (ECE)** of a substance is defined as the mass of the substance deposited or liberated at an electrode per unit charge (1 coulomb) passed through the electrolyte.
Mathematically, it is given by:
\[
\text{ECE} = \frac{\text{Equivalent weight of the substance}}{\text{Faraday's constant}}
\]
- **Equivalent weight** is the ratio of the molar mass of the substance to the valency (the number of electrons involved in the reaction for that substance).
- **Faraday's constant (F)** is the amount of electric charge per mole of electrons, approximately 96,485 coulombs per mole of electrons.
### Formula for Electrochemical Equivalent
The electrochemical equivalent can also be derived using the relationship:
\[
\text{ECE} = \frac{\text{Molar mass of the substance}}{nF}
\]
where:
- \(n\) is the number of electrons involved in the reaction (valency),
- \(F\) is Faraday's constant,
- Molar mass is the mass of one mole of the substance.
### Example
Let’s take an example with **copper (Cu)** to understand electrochemical equivalence.
- The molar mass of copper is 63.5 g/mol.
- The valency of copper in the deposition process (Cu²⁺ + 2e⁻ → Cu) is 2, since 2 electrons are involved.
The electrochemical equivalent for copper can be calculated as:
\[
\text{ECE of Cu} = \frac{63.5}{2 \times 96,485} \approx 0.00033 \text{ g/C}
\]
This means that for every 1 coulomb of charge passed, approximately 0.00033 grams of copper will be deposited at the cathode.
### Conclusion
Electrochemical equivalence is a key concept in electrolysis and electrochemistry. It helps in calculating the mass of substances deposited or dissolved in electrochemical reactions by relating it to the amount of charge passed through the electrolyte.
### Electrochemical Equivalence
The term **electrochemical equivalent** (ECE) refers to the mass of a substance that is deposited (or dissolved) at an electrode when 1 coulomb of electric charge is passed through an electrolyte solution.
This concept is based on **Faraday's Laws of Electrolysis**. According to Faraday's laws:
1. **First Law of Electrolysis**:
The mass of a substance deposited or liberated at an electrode is directly proportional to the amount of electric charge (current × time) passed through the electrolyte.
\[
m \propto Q
\]
where \(m\) is the mass of the substance, and \(Q\) is the total electric charge (in coulombs).
2. **Second Law of Electrolysis**:
The masses of different substances deposited or liberated by the same amount of electric charge are proportional to their chemical equivalents or equivalent weights.
\[
m \propto \frac{E}{F}
\]
where \(E\) is the equivalent weight of the substance, and \(F\) is Faraday's constant (approximately 96,485 C/mol).
### Definition of Electrochemical Equivalent
The **electrochemical equivalent (ECE)** of a substance is defined as the mass of the substance deposited or liberated at an electrode per unit charge (1 coulomb) passed through the electrolyte.
Mathematically, it is given by:
\[
\text{ECE} = \frac{\text{Equivalent weight of the substance}}{\text{Faraday's constant}}
\]
- **Equivalent weight** is the ratio of the molar mass of the substance to the valency (the number of electrons involved in the reaction for that substance).
- **Faraday's constant (F)** is the amount of electric charge per mole of electrons, approximately 96,485 coulombs per mole of electrons.
### Formula for Electrochemical Equivalent
The electrochemical equivalent can also be derived using the relationship:
\[
\text{ECE} = \frac{\text{Molar mass of the substance}}{nF}
\]
where:
- \(n\) is the number of electrons involved in the reaction (valency),
- \(F\) is Faraday's constant,
- Molar mass is the mass of one mole of the substance.
### Example
Let’s take an example with **copper (Cu)** to understand electrochemical equivalence.
- The molar mass of copper is 63.5 g/mol.
- The valency of copper in the deposition process (Cu²⁺ + 2e⁻ → Cu) is 2, since 2 electrons are involved.
The electrochemical equivalent for copper can be calculated as:
\[
\text{ECE of Cu} = \frac{63.5}{2 \times 96,485} \approx 0.00033 \text{ g/C}
\]
This means that for every 1 coulomb of charge passed, approximately 0.00033 grams of copper will be deposited at the cathode.
### Conclusion
Electrochemical equivalence is a key concept in electrolysis and electrochemistry. It helps in calculating the mass of substances deposited or dissolved in electrochemical reactions by relating it to the amount of charge passed through the electrolyte.