U3-2 - Metals Flashcards
Elements from a group in the periodic table all react with water.
Name this group.
Alkali metals (group 1)
Calcium reacts with water and acids to produce a gas.
Name this gas.
Hydrogen
Chemical test for hydrogen gas
Burns with a (squeaky) pop
Metal + Acid → …….
Salt + Hydrogen
Metal + Oxygen → ….
Metal oxide
Metal + Water → ….
Metal hydroxide + Hydrogen
Ores
Rocks containing metal compounds
Very reactive metals (e.g. Na) must be extracted via ____.
electrolysis
Unreactive metals can be extracted via _______.
heating alone
Metals like iron can be extracted via _____.
heating with carbon
Electrolysis
Breaking down a compound using electricity.
Bronze, brass, steel
What type of substances are these?
Alloys
Alloy
Solid mixture of two or more elements, at least one of which is a metal.
Electrolyte
Electrically conducting solution containing ions, e.g. salt solution.
Electrode
A solid conductor (metal or graphite).
Which non-metal can be used for electrodes?
Graphite
Electricity passes through metal wires as a flow of _______.
electrons
Electricity passes through an electrolyte solution as a flow of _______.
ions
What is the direction of electron flow in electrochemical cells?
From the metal higher in the electrochemical series to the one lower
(if you look at the ECS, e– flow down)
Metals far apart in the ECS produce ________ voltages than metals close together.
higher
Which pairs of metals produce higher voltages:
far apart in the ECS
close to each other in the ECS?
Metals far apart
Corrosion
A chemical reaction in which the surface of a metal changes from an element to a compound.
More _________ metals corrode faster.
reactive
Rusting
Corrosion of iron and steel
What is required for rusting to occur?
Oxygen and water
During rusting, iron atoms change into _____.
iron ions
Rust indicator
Ferroxyl
Colour change of ferroxyl indicator
Yellow to blue (if iron ions present)
What types of substances increase the rate of corrosion?
Salt solution, acid
Name the two types of rust prevention.
Physical and electrochemical
Electrochemical protection prevents rusting by __________.
providing iron with electrons
Physical protection prevents rusting by _______.
keeping oxygen and water away from the metal surface
When using sacrificial protection, you attach iron to _____.
a metal above iron in the ECS (e.g. Mg)
How does sacrificial protection prevent rusting?
The metal attached to iron corrodes and gives its e− to the iron.
(Iron only rusts if the other metal is fully corroded.)
Give one example of a substance used for physical protection from rusting
Any one of:
paint, oil, wax, grease, plastic, zinc (galvanising)
