Questions and Answers
Conductance of an electrolyte to conduct electricity in the solution is traditionally called conductance.
True
Metallic conductors and electrolytic solutions do not obey Ohm's law.
False
The formula for resistance is given by $R = \frac{ ho A}{l}$.
False
The unit of resistivity is ohm-meter ($\Omega\cdot m$).
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The formula $G = \frac{1}{R}$ represents the conductance of a material.
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When the area (A) of the cross-section is 1 $m^2$ and the length (l) is 1 m, the resistivity ($\rho$) equals resistance (R).
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According to Ohm's law, the electric current I flowing through a conductor is directly proportional to the resistance R.
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The formula $V = IR$ is derived from Ohm's law.
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Resistance is the property of a conductor that facilitates the flow of electrical current.
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The equation $G = \frac{1}{R} = \frac{A}{ ho l}$ expresses conductance in terms of resistivity, length, and cross-sectional area.
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Study Notes
Electrochemistry
- Branch of chemistry that deals with conversion of chemical energy into electrical energy and vice versa
Spontaneous and Non-Spontaneous Reactions
- Spontaneous reactions occur automatically and release energy
- Non-spontaneous reactions occur non-automatically and require an external force
Electrochemical Cells
- Devices that convert chemical energy into electrical energy
- Also known as voltaic and Daniell cells
- Electric potential is 1.1V
Galvanic Cells
- Systems that convert chemical energy into electrical energy
- Cell potential is the potential difference between the two electrodes of a galvanic cell
Standard Electrode Potential
- Potential difference of individual half-cell cannot be measured
- Standard Hydrogen Electrode (SHE) is assigned a zero potential at all temperatures
Standard Hydrogen Electrode (SHE)
- Consists of a Pt electrode coated with platinum black
- Dipped in an acidic solution with pure H2 gas bubbled through it
- Conditions: 1 atm pressure, 298K temperature, and 1M concentration
Electrochemical Series
- Arrangement of metal/metal electrodes in their increasing/decreasing order of electrode potential
- Examples of electrode potentials: Li (-3.05 V), K (-2.83 V), Ca (-2.82 V), etc.
Eluarine and Di
- Eluarine is the strongest oxidizing agent
- Di is the most powerful reducing agent
Ecell and Reducing Power
- Ecell is a measure of the reducing power of a substance
- The more stable the reduced form of a substance, the more stable the substance itself
Nernst Equation
- $E_{cell} = E_0 - \frac{RT}{nF}ln(Q)$
- Where E0 is the standard electrode potential, R is the ideal gas constant, T is the temperature, n is the number of moles of electrons, F is Faraday's constant, and Q is the reaction quotient
Gibbs Free Energy
- Reversible work done by a Galvanic cell is equal to the decrease in its Gibbs energy
- $\Delta G = -nFE_{cell}$
Equilibrium Constant
- $K = exp(\frac{-\Delta G}{RT}) = exp(\frac{nFE}{RT})$
- $K = E_{cell} * \frac{96500}{8.314 * 298} = E_{cell} * 38.91$
Conductance of Electrolytic Solutions
- Conductance of an electrolyte is the ability to conduct electricity in the solution
- Electrolytic solutions obey Ohm's law: I = V/R, where I is the electric current, V is the voltage, and R is the resistance
Resistivity
- Defined as the resistance offered by a conductor of unit length and unit area of cross-section
- Unit of resistivity: ohm-m
Conductance
- $G = \frac{1}{R} = \frac{A}{\rho l} = conductivity x A/l$
- Conductance is the reciprocal of resistance
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Description
Learn about electrochemistry, the branch of chemistry that deals with the conversion of chemical and electrical energy. Understand spontaneous and non-spontaneous reactions and their applications.
