16 Questions
What is the relationship between electrical properties and chemical reactions?
Electrochemistry
What type of energy is converted into electrical energy in a galvanic cell?
Chemical energy
What is the charge of the cathode in an electrolytic cell?
Negative (-)
What type of reaction occurs in an electrolytic cell?
Nonspontaneous reaction
What is the electrode at which oxidation occurs in an electrochemical cell?
Anode
What is the instrument used to measure electrical properties in electrochemical cells?
Instrumental methods
What type of cell generates a current-potential?
Galvanic cell
What is the process that occurs at the cathode in an electrochemical cell?
Reduction (gain of electrons)
What is the purpose of a voltmeter in an electrochemical cell?
To measure the potential of the complete cell
What is the equation to calculate the potential of an electrochemical cell?
Ecell = E(cathode) - E(anode)
What type of electrochemical method measures the conductance of a solution?
Conductimetry
What is the purpose of the Nernst equation in potentiometry?
To relate the potential to the concentration of the analyte
What is the formula to calculate the potential of an electrode at 25°C for a cation?
E25°c = E° + (0.0591/n) log [Mn+]
What is the purpose of an indicator electrode in potentiometry?
To indicate the concentration of the analyte
What is the classification of electrochemical methods based on?
Method of analysis
How many types of electrochemical methods are there?
3
Study Notes
Electrochemical Cells
- Electrochemical cell potential difference (emf) can be experimentally measured using a voltmeter: Ecell = E (cathode) – E (anode) = E (right) – E (left)
- Electrode potential of each half cell cannot be experimentally measured but can be calculated using the Nernst equation: Ox + ne- = Red
Classification of Electrochemical Methods
- There are three types of electrochemical methods:
- Potentiometry
- Conductimetry
- Voltammetry
Potentiometry
- Measures the electrical potential developed by an electrode in an electrolyte solution at zero current flow, using the Nernst equation
- Nernst equation relates potential to concentration of analyte: E25°c = E° + (0.0591/n) log [Mn+]
- Potentiometric methods are based on measurements of the potential of electrochemical cells in the absence of appreciable currents (i.e. 0)
Conductimetry
- Measures the conductance of a solution, which depends on the concentration of its ions, using inert electrodes and alternating current
Electrochemistry
- Is the relationship between electrical properties and chemical reactions
- Electrical properties measured as: voltage, current, resistance
- Measurements are carried out by certain instruments, thus the methods are called instrumental methods
Electrochemical Cells
- Divided into two cells: Galvanic cell and Electrolytic cell
- Galvanic cell: Chemical energy is converted into electrical energy
- Electrolytic cell: Electrical energy is converted into chemical energy
Comparing Galvanic Cell and Electrolytic Cell
- Galvanic cell:
- Generates current-potential
- Chemical energy is converted into electrical energy
- Spontaneous reaction to occur
- Cathode is positive (+), Anode is negative (-)
- Electrolytic cell:
- Consumes current-potential
- Electrical energy is converted into chemical energy
- Non-spontaneous reaction to occur
- Cathode is negative (-), Anode is positive (+)
Electrodes
- Cathode: The electrode at which reduction occurs (gain of electrons), usually metal electrodes
- Anode: The electrode at which oxidation occurs (loss of electrons), usually metal electrodes
This quiz covers the measurement of electrochemical cell potential, including the use of voltmeter and Nernst equation. It also explains the calculation of electrode potential and the difference between cathode and anode.
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