Copper sulfate and electroplating
Introduced| English | Meaning |
|---|---|
| copper sulfate/ˈkɒpə ˈsʌlfeɪt/ | copper sulfate |
| electroplating/ɪˌlektrəʊˈpleɪtɪŋ/ | Using electrolysis to deposit a metal coating onto a conducting object. |
| corrosion/kəˈrəʊʒn/ | The gradual destruction of a material through chemical or electrochemical reactions with its surroundings. |
Useful electrolysis
- Electrolysis isn't just a lab curiosity — it purifies metals and coats objects.
- Two important uses are electrolysing copper sulfate 硫酸铜 and electroplating 电镀.
Electrolysing copper sulfate with copper electrodes is used to:
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The impure copper anode dissolves; pure copper deposits on the cathode.
Coating an object with a thin layer of metal using electrolysis is called ______.
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The object is the cathode.
Electrolysis of copper sulfate
- With carbon electrodes, copper forms at the cathode and oxygen at the anode.
- With copper electrodes, the anode dissolves and copper is deposited on the cathode — used to purify copper.
Electrolysis of molten lead bromide: ions move to the electrodes and are discharged
Electrolysis of copper(II) sulfate
Cu²⁺ ions move to the cathode and are discharged as copper metal, which plates onto it — exactly how electroplating coats an object with copper.
In electroplating, the object to be coated is the:
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The object is the cathode, where metal is deposited.
In electroplating, the plating metal forms the anode.
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The anode supplies the metal that coats the cathode.
Electroplating
- Electroplating coats an object with a thin layer of metal using electrolysis.
- The object to be plated is the cathode; the plating metal is the anode.
To electroplate, make the object the cathode and the plating metal the anode, in a solution of the plating-metal ions
An electrolysis cell splits a compound using electricity
Why is electroplating used? (Select all that apply.)
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Electroplating coats, not melts.
Why electroplate
- To improve appearance (e.g. silver-plated cutlery) or to protect from corrosion 腐蚀.
- A thin coat of an expensive or resistant metal does the job cheaply.
Worked example. To silver-plate a spoon, the spoon is the cathode and a bar of silver is the anode, in a silver-salt solution. Silver dissolves from the anode and coats the spoon.
You've got it
- electrolysing copper sulfate with copper electrodes purifies copper (anode dissolves, cathode gains)
- electroplating coats an object with metal: the object is the cathode, the metal the anode
- it improves appearance and protects against corrosion