C4 Flashcards
Where are most metals obtained from?
Ores found in the Earth’s crust
Name a metal that is not extracted from an ore and explain why.
Gold because it is so unreactive it doesn’t combine with oxygen in the environment.
Define oxidation and reduction.
Oxidation is when a reactant gains oxygen or loses electrons.
Reduction is when a reactant loses oxygen or gains electrons.
What is a displacement reaction?
when a more reactive element displaces a less reactive element from it’s compound. Both metals and non metals take part in displacement reactions.
In metal displacement reactions, is the reactive metal oxidised or reduced?
Oxidised
What is electrolysis?
A chemical process that decomposes an electrolyte using electrical energy from a direct current (DC) supply.
Describe how iron is extracted from it’s ore.
Iron ore is heated with carbon (the carbon displaces the iron). The iron is reduced _ loses it’s oxygen to the carbon.
Describe how aluminium is extracted from it’s ore.
Aluminium is extracted by electrolysis.
Why is iron not extracted form it’s ore using electrolysis?
It is cheaper to displace it with carbon.
What does the pH scale measure?
The acidity or alkalinity of a solution.
What is an indicator?
A substance that has different colours, depending on the pH of the solution it is in.
What is an acid?
Acids dissolve in water to make solutions with a pH of less than 7.
What is a base?
It is a substance that can react with an acid to make salt and water.
What type of reaction is it when an acid reacts with a base?
Neutralisation
What are the products of the following neutralisation reactions?
- Metal + acid
- Metal + oxide+acid
- Metal hydroxide + acid
- Metal carbonate + acid
- Salt+hydrogen
- Salt +water
- Salt + water
- Salt+water+carbon dioxide
What are acids and alkalis sources of?
Acids - hydrogen irons
Alkalis - hydroxide ions
Explain why water is produced when an acid reacts with an alkali?
The hydrogen irons (H+) from the acid react with the hydroxide ions (OH) from the alkali to form water (H2O).
Give three examples of string acids?
Hydrochloride (HCI)
Nitric (HNO3)
Sulphuric (H2SO4)
Give three examples of weak acids.
Ethanoic (ch3cooh)
Citric
Carbonic
What is a dilute solution?
A solution that contains a relatively small amount of dissolved solute.
What is a concentrate solution?
A solution that contains a relatively large amount of dissolved solvent.
What is a strong acid?
An acid which completely dissolved into ions in a solution.
What is a weak acid?
An acid which partially dissociates in a solution.
What is pH a measure of?
The concentration of hydrogen ions.
What are positively charged ions called?
Cations
What are negatively charged ions called?
Anions
What is the positive electrode called?
Anode
What is the negative electrode called?
Anode
What is the negative electrode called?
Cathode
How do ions move during electrolysis?
The cations migrate to the cathode.
The anions migrate to the anode.
Does oxidation happen at the cathode or anode?
Anode
Does reduction happen at the cathode or anode?
Cathode
What is preferential discharge?
The relatively least reactive ions are preferentially discharge as elements. It is based on the reactivity series.
