Topic 3 - Metals

Question 1

Solubility of compounds

Answer 1

Soluble:
K Na NH4
Nitrates
Hdrogencarbonate
Halides - x silver + lead
Sulphates - x silver + lead + Ca + Ba

Insoluble
Carbonate - K Na NH4
Oxide - K Na Ca
Hydroxide - K Na Ca slightly

Question 2

Use of metals + reasons
Iron
Cu
Al
Titanium
Gold
Silver

Answer 2

Iron:
Building materials - cheap amd strong

Copper:
Wires - ductile + good electrical conductor
Pipes - non toxic

Aluminium:
Power cables - low density
Aircraft - strong
Soft drink cans - non toxic
Window frame - corrosion resistance

Titanium:
Metal implants - biocompatible

Gold:
Shield for radiation - high reflective index

Silver:
Electronics - good conductor

Question 3

Extraction of metals from ores

Answer 3

K Na Ca Mg Al
Electrolysis

Zn Fe Pb Cu
Carbon Reduction

Hg Ag
Heating

Au
Physical, eg panning

Question 4

Extracting of metal sulphide

Answer 4

MS + O2 -> MO + SO2

MO + C -> M + CO2

Question 5

Metal + Oxygen

Answer 5

Metal oxides

K- Lilac flame white powder
Na- Golden yellow flame white powder
Ca- Brick red flame white powder
Mg- Bright white flame white powder
Al-  white powder

Zn- yellow hot white cold powder
Fe- sparks + black solid

Pb- orange powder when hot
Cu- Black powder
Hg- Red powder

Question 6

Reaction: Metal + H2O

Answer 6

K Na Ca + Water -> Metal Hydroxide + Hydrogen
Colourless solution

Mg + Hot Water -> Metal Hydroxide + Hydrogen

Mg Al Zn Fe + Steam -> Metal Oxide + Hydrogen
White powder
Fe Black powder

Question 7

Reaction: Metal + Acid

Answer 7

Ca + H2SO4 stops after a while

Pb + HCl/H2SO4 stops after a while

Question 8

Displacement Reaction
Definition
Observation

Answer 8

Metal higher reactivity deplace metal lower reactivity
From solution of lower reactivity

M1 dissolves
Solid deposit of M1
Colour changes of solution

Question 9

Corrosion

Definition

Answer 9

Gradual deterioration of metal

By reaction of air and moisture

Question 10

Rusting
Definition
Equation

Answer 10

Corrosion of metals

4Fe + 3O2 + 2n H2O -> 2Fe2O3▪nH2O
Hydrated iron (III) oxide

Question 11

Factors.of rate of rusting ×5

Answer 11

Acidic
Soluble ionic compound
High temp
Less reactive metals attaching
Bent scratched area

Note: Alkaline slows down rusting

Question 12

Rust indicator
Consist of
Colour
Significance

Answer 12

Gel - easier observation of diffusion
NaCl - increases rate of rusting
Hexacyanoferrate (lll) - blue - Fe ions
Phenolphthalein - pink - OH-

Question 13

Coating of iron for protection ×6

Answer 13

Painting
Greasing
Plastic covering

Tin plating
Galvanization (zinc)
Elcectroplating

Question 14

Ways of protecting Fe ×4

Answer 14

Coating
Cathodic Protection
Sacrificial Protection
Alloys

Question 15

Cathodic Protection

Example

Answer 15

Connect to negative terminal
Positive - graphite
In electrolyte

Gives e- to Fe

Steel piers legs, Car body

Question 16

Sacrificial Protection

Example

Answer 16

More Reactive metal connects to Fe
Lose e- more readily
Corrode instead of Fe

Underground Pipelines

Question 17

Alloys types, composition, usage ×7

Answer 17

Bronze - copper - Statue
Stainless Steel - iron - Thermal cup
Brass - copper zinc - Saxophone
Duralumin - aluminium - airplane
Titanium Alloy - Titanium - badminton racket
Coinage metals - copper - coins
Solder - tin lead - solder - low meltong point

Question 18

Aluminium Anodization

Answer 18

Increase thickness of oxide layer
Al positive
Al sheeg negative