Topic 5- Transition metals + alloys Flashcards
(34 cards)
What are most metals?
Transition metals
Transition metals have high…
-Bioling point
-Density
Do transition metal form coloured compounds?
-Yes
What are transition metals good for?
-Catylists
-E.g iron in haber process
What does the broad range of transition metals mean?
-Many different ionic charges
What is the haber process?
Nitrogen + Hydrogen —> Ammonia
For plant fertiliser, grows all food
What temp + pressure is the reaction vessel?
haber
-450 degrees
-200 atm
-Iron catalyst helps
What type of reaction is the haber reaction and what does this mean we need to do?
-Reversable
-Seperate ammonia from H and N atoms
-Ammonia has lower boiling point so we condense it
What is rust and how is it made?
Metal + oxygen + water
How does rust corrode metals?
-Surface layer rusts
-Rust layer flakes off
-This repeats
What is corrsion?
Destruction of metals by chemical reactions
What does oxidation of metals cuase?
Rusting
How can rusting of metals be prevented x3?
-Excluding oxygen
-Exclusion of water
-Sacrificial protection
How can we exclude oxygen + water from metal to prevent rust?
-Paint
-Coat with plastic
-Coat with oil or grease
-Alluminium has an oxide coat so protected from further oxidation + water
How can we exclude water only to prevent metal rust?
-Use a desiccant (absorbs water)
-E.g calcium carbonate
How can we exclude oxygen only to prevent metal rust?
-Place in a vacuum
How can we use sacrificial protection?
-Galvanise/coat metal with another
-Less reactive metal
-Wont rust
e.g zinc galvanises iron
What can electroplating be used for?
-Improve appearence + strength of metal
plate metal with another
How does electroplating strengthen metals?
-Acts as a barrier to prevent rust
How does electroplating improve appearence?
-Plate with less reactive metal to prevent rust
-Cheaper, plate with gold
How is electroplating done?
-Electrolysis
-Cathode is metal to be plated
-Solution + anode is metal to plate
solution + anode ions r attracted to cathode
What is an alloy?
-Mxture of 2 or more elements
-Atleast one is a metal
Why are alloys used to strengthen materials
- Metals such as gold, aluminium and iron are too soft
- In a pure metal all atoms are unifrom meaning they can slide over eachother
- Adding different element disrupts uniform atoms + no longer as maluable
What and why is iron alloyed into?
-Steel
-Mix of carbon + iron + more
-Makes it stronger
