C6.1 - Introduction To Electrolysis (Finished) Flashcards
What does electrolysis mean?
Breaking down a substance by electricity
What is the compound that is broken down in electrolysis called?
The electrolyte
How is an electric circuit for electrolysis laid out?
Two electrodes dipping into the electrolyte with a gap between them. One is connected to the positive side of a power supply and the other to the negative
The positively charged electrode is called the _____ and the negitively charged one the _____
Anode, cathode
What are the electrodes made of and why?
An unreactive substance so they do not react with the electrolyte or products
During electrolysis, _____ charged _____ move to the _____ and _____ charged ones to the _____
Positively, ions, cathode, negatively, anode
What happens to ions when they reach the electrodes?
They loose their charge and become elements
Why can ionic compounds only be electrolysed when molten or dissolved in water?
Because their ions become free to move and carry their charge
Why is molten electrolysis impractical?
Many ionic substances have very high melting points so a lot of energy is needed to melt them
Why is water electrolysis impractical?
Water also forms ions, so the products at the electrodes are not always what expected (see 6.2)
Metals of what reactivity can be used in aqueous electrolysis can be deposited without water ions stuffs?
Metals below hydrogen in the reactivity series, very low
Can covalent compounds be electrolysed?
No, unless they react in water to form ions (e.g. acids)
Why do ionic compounds not conduct electricity when solid?
Their ions are in fixed positions in a giant lattice
In zinc chloride which ions will go where?
The positive Zn2+ ions will go to the cathode, and negative Cl- to the anode
How do ions move in electrolysis and why?
During electrolysis, positively charged ions move to the cathode and negative charged ions move to the anode, as opposite charges attract
