C15 - Using Our Resources 2️⃣✅
No description yet. This curated deck is ready for daily study.
Card preview (24)
What is corrosion?
The destruction of materials by chemical reactions with substances in the environment
What is an example of corrosion?
Rusting
What 2 things are requried for iron to rust?
air and water
How can corrosion be prevented?
Applying a coating that acts as a barrier such as greasing, painting or eelectroplating.
What is galvanisation?
Applying a thin layer of zinc to metals such as steel or iron (Zinc more is more reactive so acts as a ‘sacrificial’ coating to prevent corrosion/ rusting)
What is an alloy?
An alloy is a mixture of two or more elements, at least one of which is a metal
What is a carat?
A method to measure the percentage of pure gold in an alloy of gold
What percentage of gold is 24?
100%
What percentage of gold is 18?
75%
What are the properties of the sructure of a pure metal?
• All atoms are the same size • All atoms are in neat layers • Malleable (due to the sliding layers of delocalsied electrons)
What are the properties of the structure of an alloy?
• 2 or more different sized atoms • Layers/ patterns are disrupted • Layers cant slider as easily therefore alloys are stronger and less mallelable than pure metals
What is an example of an alloy of iron?
Steel
What are the propeties of high carbon steel?
Strong but brittle
What are the properties of low carbon steel?
Softer and more easly shaped
What are the properties of steels containing nickel & chromium (stainless steel)?
Hard and resitant to corrosion
What is a thermostetting polymer?
Polymers that covalent bonds require alot of energy to break and therefore not melt when we heat them. This is because they have strong covalent bonds forming ‘cross links’ between their polymer chains
What is a thermosoftening polymer?
Polymers that have weak intomolecular forces that break easily when heated, causing the polymer to melt when they are heated. This is due to their tangled web of unstructred polymer chains and them being held together by weak intomolecular forces
What type of thermo-polymer is this structure?
Thermosetting
What type of thermo-polymer is this structure?
Thermosoftening
How is high density poly(ethene) made?
Low temperatures, low pressure & a catalyst
How is low density poly(ethene) made?
Moderate temperatures, high pressure & catalyst
What is the properties of high density of poly(ethene)?
More ridgid than LDPE but stronger
What is the properties of low density poly(ethene)?
More flexible than HDPE but weaker
How are ceramics made?
By shaping and firing a nonmetallic mateiral e.g. clay at a high temperature