Topic 5a- Transition metals, alloys and corrosion (paper 1) Flashcards
What are the melting points of transition metals?
All high except for mercury which is a liquid at room temperature.
What are the densities of transition metals
They all have high densities.
What are the typical properties of transition metals?
- high melting points
- high densities
- tendency to form coloured compounds
- good catalysts
What is brass an alloy of?
Copper and zinc
What is bronze an alloy of?
Copper and tin
What is a key point to note about gold in jewellery?
Not pure gold as it is too soft. Often alloys including zinc, copper and silver.
What does 24 carat mean?
100% gold
What would 18 carat mean?
75% gold
What is magnalium made from?
Magnesium and aluminium
What is the equation for corrosion
metal + oxygen + water → hydrated-metal-oxide
What is corrosion?
The oxidation of metals.
What are the two methods that can be used to prevent corrosion?
- creating a barrier
- sacrificial method
- exclusion of water
- exclusion of oxygen
What is electroplating?
Using electrolysis to coat the surface of one metal with another metal.
What is sacrificial protection?
Placing a more reactive metal witht the other metal to stop elements reacting with the less reactive one.
What are uses of brass?
- Has low friction so is often used in water taps or door fittings
