Quantitative Electrochemistry
Related Examples and Practice Problems
Additional Worked Out Examples/ Practice
Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures
Separation techniques: Selected and explaining limitation of appropriate separation
Relating Properties to Composition: Predicting classification based on descriptive properties
Topic Summary & Highlights
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Core Concept
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Practice Tips
Quantitative electrochemistry relates current, time, and chemical quantities.
Use Faraday’s laws to calculate the mass of products or the charge required.
Apply the ideal gas law to determine the volume of gases produced.
Mastering these concepts is essential for applications in electroplating, energy storage, and industrial processes.
Core Concept
Electric Charge (Q)
Definition: The total electric charge transferred during an electrochemical reaction.
Formula: Q = I ⋅ t where:
Q: Charge (Coulombs (C)).
I: Current (Amperes (A)).
t: Time (seconds (s)).
Faraday's Constant (F)
Represents the charge of one mole of electrons: F=96,485 C/mol
Moles of Electrons (n)
The amount of charge relates to the moles of electrons transferred: $n_{\text{e}^-} = \frac{Q}{F}$
Faraday’s Laws of Electrolysis
First Law:
The mass (m) of a substance deposited or liberated at an electrode is proportional to the charge passed through the electrolyte. m=Z⋅Q Where:
Z: Electrochemical equivalent (g/C).
Q=I⋅t.
Second Law:
For the same amount of charge, the mass of different substances produced is proportional to their molar masses (M) divided by the number of electrons (n) transferred. $m \propto \frac{M}{n}$
Quantitative Relationships
Mass of Product: m = $\frac{M \cdot Q}{n \cdot F}$
Where:
m: Mass of the product (g).
M: Molar mass (g/mol).
n: Number of electrons in the half-reaction.
Volume of Gas:
For gases produced at electrodes, use the ideal gas law: V = $\frac{nRT}{P}$ Where:
V: Volume (L).
R: Ideal gas constant (0.0821 L·atm/mol·K).
T: Temperature (K).
P: Pressure (atm).