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A blue solution is connected to a battery. A reddish brown metal builds up on one electrode and gas bubbles form on the other. What has happened to the compound?
AIt has melted into a liquid
BIt has mixed with the water
CIt has boiled away as a gas
DIt has split into its elements
Answer & Solution
Correct answer: D. It has split into its elements
1. Two new materials appear where before there was only one dissolved compound.
2. A reddish brown coating on one electrode is the metal copper.
3. Bubbles on the other electrode are a gas being released there.
4. So the compound has been broken down into simpler substances by electrical energy.
5. Melting and boiling are changes of state and would not make two new materials.
6. Simple mixing would leave the compound unchanged, so that option is wrong.
_Source: Siyavula Natural Sciences Grade 8 (CC BY 4.0), The decomposition of copper chloride_
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