Electroplating and fuel cells
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 3 worked examples, 7 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Two ways electricity meets chemistry
- What is electroplating?
- The set-up
- What happens
Read the transcript of the teaching part
Last time
Before we start: last time, in Brine, copper, plating and fuel cells, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Two ways electricity meets chemistry
A silver spoon that is really steel, and a car that runs on hydrogen with only water coming out of the exhaust. In the first, electricity makes a chemical change, which is electroplating. In the second, a chemical change makes electricity, which is a fuel cell. They are opposites.
What is electroplating?
Electroplating is coating the surface of an object with a thin layer of metal, using electrolysis. We do it for appearance, to protect the object from corrosion, or to improve how well it conducts. For example, steel can be plated with chromium for car parts, or with silver for cutlery.
The set-up
The object to be plated is the cathode, the negative electrode. The anode is a piece of the plating metal. To plate with silver, use a silver anode. The electrolyte is a solution containing ions of the plating metal. For silver, that is silver nitrate solution.
What happens
At the cathode, silver ions gain electrons and are deposited as silver on the spoon. At the anode, silver atoms lose electrons and dissolve as silver ions. The ions removed at the cathode are replaced at the anode, so the concentration of the solution stays constant.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Hydrogen-oxygen fuel cells · Hydrogen–oxygen fuel cells.
The whole chapter: Electrochemistry, Electrochemistry.
Chapter 4: Electrochemistry
- Principles of electrolysis and molten compounds 7 min
- Predicting products and half-equations 7 min
- Electrolysis of brine and copper(II) sulfate 6 min
- Electroplating and fuel cells 7 min
Also for IGCSE Chemistry 0620
Which topics come up most in IGCSE Chemistry 0620 past papers, counted from every paper since 2004.