MDCAT Chemistry · Chemistry · Electrochemistry. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
When a metal dips into a solution of its own ions, a potential difference is set up. It cannot be measured alone, so every electrode is compared with the standard hydrogen electrode (SHE), which is given the value 0.00 V. The result is the standard electrode potential, E°, written as a reduction potential.
A more negative E° means the metal loses electrons more easily: it is a stronger reducing agent. A more positive E° means the species gains electrons more easily: it is a stronger oxidising agent.
In a galvanic cell a spontaneous redox reaction produces a current. In an electrolytic cell a current from outside forces a non-spontaneous reaction to happen.
Students subtract the potentials the wrong way or change the sign twice. Keep both values as reduction potentials and take cathode minus anode; the more negative electrode is the anode.
Answer: Zinc is the anode; emf = 1.56 V, with electrons flowing through the wire from zinc to silver.
Type what you are stuck on. The helper finds the explanation, worked examples and the notes to read, free and instant.
← Oxidation numbers and redoxIonic and covalent bonding →Take a MDCAT Chemistry test