C6 Flashcards
Which metals are extracted using electrolysis and why?
Potassium, sodium, calcium, magnesium and aluminium because they are higher than carbon in the reactivity series.
What are elements that are less reactive than carbon extracted by?
Reduction by carbon because carbon is cheap and abundant.
How does reduction by carbon work?
The metal oxide loses its oxygen to form a pure metal. This involves heating the metal oxide with carbon in the form of coal.
What is electrolysis?
A process used to extract reactive metals from their molten ores.
What is the anode?
It is a positive electrode that is made from carbon because it’s a good conductor and it’s cheap. Carbon dioxide is formed at the anode.
What is cathode?
A negative electrode where aluminium is formed.
What is a disadvantage of electrolysis?
A lot of energy is needed to melt the solid and produce electrical current which is expensive.
What are cations?
Positively charged ions that move towards the cathode.
What are anions?
Negatively charged ions that move toward the anode.
Do metals go to the cathode or anode and why?
Metals go to the cathode because they form positively charged metal ions because opposites attract.
Do non- metals go to the cathode or anode?
Non-metals go to the anode because they form negatively charged non- metals which are attracted to the non- metals ions.
What happens to cations during electrolysis?
They gain electrons at the cathode.
What happens to anions during electrolysis?
They lose electrons at the positively charged anode.
What is the balanced symbol equation for the reaction of copper(II) oxide with carbon?
2CuO +C arrow 2Cu + CO(2)
If it says in terms of oxygen..
You say if they gained or lost oxygen.
Why is gold easy to extract?
It is found as a pure metal so no extraction process is needed.
Why was sodium hard to extract a long time ago?
Sodium is very reactive so was found in compounds so the technology needed to extract it wasn’t available.
What is an ore?
A natural rock that contains valuable minerals that can be extracted because its economically worthwhile.
What elements do you not use electrolysis or reduction for?
Gold, silver and platinum
What’s a disadvantage of reduction by carbon?
It doesn’t purify the metal.
How do you heat a blast furnace?
Hot air reacts with the coke (carbon) to produce carbon dioxide and heat energy to heat up the furnace.
More coke is added to the furnace which turns the carbon dioxide in carbon monoxide. In this reaction, iron oxide is reduced to iron and the carbon is oxidised to carbon dioxide.
What is the symbol equation for heating a blast furnace?
CO2(g) + C(s) ——> 2CO(g)
2Fe(2)O(3)+ 3C(s) ——> 4Fe+3CO(2)(g)
What is the role of cryolite in electrolysis?
Reduces melting point of aluminium oxide
Reduce energy requirements
Make the process cheaper to produce aluminium
The anode is made of graphite, why does it have to be replaced often?
Graphite reacts with the oxygen and the anode is burnt away of is oxidised.
