Metals Flashcards
1
Q
Chemical name for rust
A
hydrated iron (III) oxide
2
Q
2 stages of Iron rusting
A
- Iron is oxidised by oxygen, forming Iron (III) oxide
- Iron (III) oxide is hydrated by water
3
Q
Balanced equation for oxidation of Iron
A
- 4Fe + 3O2 –> 2Fe2O3
4
Q
Balanced equation for hydration of Iron (III) oxide
A
Fe2O3 + H2O –> Fe2O3 x H2O
5
Q
Rusting prevention methods
A
- Barriers
- Sacrificial protection
- Galvanisation
6
Q
What is barrier protection (rust)
A
- Coating iron in paint, oil, grease or plastic to prevent iron coming into contact w/ oxygen or water
- only works when barrier is intact- if broken, rust happens
7
Q
What is sacrificial protection (rust)
A
- Attaching block of more reactive metal (e.g magnesium) to the Iron
- Iron is displaced from rust as soon as it forms
-however Mg has to be replaced often
8
Q
Equation for sacrificial protection
A
- Magnesium + iron(III) oxide –> magnesium oxide + iron
9
Q
what is galvanisation (rust)
A
- Coating iron in zinc
- works initially as barrier protection, but if it cracks then also sacrificial as zinc more reactive than iron
10
Q
What is an alloy?
A
Mixture of metal with one or more other element, usually another metal or carbon
11
Q
Common alloys:
A
- Steel ( Iron + carbon)
- Brass (copper + zinc)
- Bronze ( copper + tin)
12
Q
Positives of alloys
A
- Harder/ less malleable than normal metals
13
Q
Why are alloys harder than normal metals?
A
- made up of different sized atoms/ions
- layers cannot slide over each other as easily
- therefore less malleable
14
Q
Use of Iron
A
- To make steel, as it is more useful
15
Q
Use and contents of low carbon steel
A
- Iron, 0.1% carbon
- used for making Ships, cars as they are strong but can be hammered to dif shapes
16
Q
Use and contents of high carbon steel
A
- Iron, 1% carbon
- used for tools e.g screwdrivers, as they are less malleable than low carbon steel
17
Q
Use and contents of stainless steel
A
- Iron, 1% carbon, 10% Chromium
- used for cutlery, cooking utensils as Chromium forms oxide layer preventing corrosion- stay shiny
18
Q
use of copper + why
A
- wires, pans, pipes
- as good conductor of heat and electricity
- unreactive and malleable
19
Q
use of aluminium + why
A
- aircraft bodies, power cables
- as is low density, but is very strong and conductive
20
Q
What are metal ‘ores’
A
- rocks containing metals as compounds with Sulphur and Oxygen
21
Q
why are metals in ores compounds with Oxygen and Sulphur
A
- Over long periods of time underground metals have reacted with Oxygen and Sulphur
22
Q
reactivity series (from least reactive)
A
- Gold (Au)
- Silver (Ag)
- Copper (Cu)
- [Hydrogen (H)] - not metal
- Lead (Pb)
- Iron (Fe)
- Zinc (Zn)
- [Carbon (C)] - not metal
- Aluminium (Al)
- Magnesium (Mg)
- Calcium (Ca)
- Lithium (Li)
- Sodium ( Na)
- Potassium (K)
23
Q
Why are Gold and Silver native ( not in ores)
A
- not reactive enough to combine with oxygen or sulphur
- therefore found chemically uncombined
24
Q
Methods of metal ore extraction
A
- Using electricity
- Carbon extraction
25
How does carbon extraction work
- metals less reactive than carbon can be displaced from their ore when heated with carbon
26
What is a displacement reaction
- When more reactive metals displace less reactive metals from their compounds
27
example of displacement reaction
- magnesium displaces copper from copper sulphate
28
equation for magnesium/copper sulphate displacement reaction
Magnesium + Copper sulphate --> Magnesium sulphate + copper
29
Main observations to think about for displacement reaction
- Solid colour change
- solution colour change
30
Two components of metal structure
- lattice of positive metal ions
- sea of delocalised electrons
31
What is metallic bonding
The electrostatic attraction between the positive metal ions and negative delocalised electrons
32
Metallic bonding is...
a very strong attraction
33
properties of metals
-High melting points
-conduct electricity
-Malleable
34
Why metals have high melting point
- metallic bonding very strong, lots of energy needed to break bonds
35
why metals conduct electricity
- delocalised electrons free to move through lattice, carrying charge
36
why metals malleable
layers of metal ions can slide over each other
37
metal and water reaction equation
metal + water --> metal hydroxide + hydrogen
38
example of metal and water reaction
magnesium + water --> magnesium hydroxide + hydrogen
39
observations made in metal and water reaction
- effervescence due to hydrogen gas produced
- solid disappearing due to being used up in reaction
40
group 1 (alkali) metals reaction with water
- violent reaction
- as they are highly reactive
41
example of group 1 metal and water reaction
lithium + water --> lithium hydroxide + hydrogen
42
Reactions of Li, Na and K in water similar observations
- solid floats- less dense than water
- effervescence- production of H gas
- solid moves- effervescence propels it around surface
- solid disappears- used up in reaction
43
colour of universal indicator in solution of metal and water after reaction?
- dark blue
- metal hydroxide created- alkali
44
reactivity of group 1 metals down the group
- more reactive
45
why are group 1 metals reactive
- only need to lose 1 outer shell electron to get full outer shell
46
why is it easier for group 1 metal atoms to react further down group?
- 1 outer shell electron must be lost to react
- down group=further away from nucleus
- further away from nucleus- weaker attraction between electron and nucleus
- less energy needed to break attraction
47
metal and steam reaction equation
metal + steam --> metal oxide + hydrogen
48
example of metal and steam reaction
magnesium + steam --> magnesium oxide + hydrogen
49
why do metals react with cold water and hot steam differently?
- steam has more energy
- therefore both hydrogen bonds in water can break
- therefore metal 'oxide' not 'hydroxide'
50
how do conduct metal and steam reaction ( Mg)
- horizontal tube
- wet wool and magnesium placed inside
- tube heated
- Hydrogen gas (product) escapes tube and is ignited to safely destroy it
51
Acid and metal reaction
metal + acid --> salt + hydrogen
52
example of acid and metal reaction
magnesium + sulphuric acid --> magnesium sulphate + hydrogen
53
observations of metal and acid reaction
- metal disappears as it is used in reaction
- effervescence as hydrogen gas is produced
54
why do group 1 all have the same chemical properties
they all have one electron in their outer shell
55
characteristics of group 1 metals
- need to be stored in oil
- soft so can be cut easily
- oxidise quickly so become dull when cut
- low mtp/density
