Metals

Question 1

general physical properties of metals

Answer 1

Metals​ ​have​ ​giant​ ​structures​ ​of​ ​atoms​ ​with​ ​strong​ ​metallic​ ​bonding, Thus:
-most​ ​metals​ ​have​ ​high​ ​melting​ ​and​ ​boiling​ ​points.
-​can​ ​conduct​ ​heat​ ​and​ ​electricity​ ​because​ ​of​ ​the​ ​delocalised
electrons​ ​in​ ​their​ ​structures.
-Metals are malleable as layers​ ​of​ ​atoms​ ​in​ ​metals​ ​are​ ​able​ ​to​ ​slide​ ​over​ ​each​ ​other,​ ​so​ ​metals can​ ​be​ ​bent​ ​and​ ​shaped, And are also ductile (can be stretched into wires)

Question 2

general chemical properties of metals

Answer 2

-Metals​ ​will​ ​lose​ ​electrons​ ​to​ ​form​ ​+​ ​ions
Metals​ ​+​ ​oxygen​ ​->​ ​metal​ ​oxides, oxidation​ ​reactions​ ​because​ ​the​ ​metals​ ​gain​ ​oxygen (OILRIG)
-Reduction​ ​is ​opposite, ​metals​ ​lose​ ​oxygen
Acid​ ​+​ ​Metal​ ​->​ ​Salt​ ​+​ ​Hydrogen

Question 3

why alloys are used instead of pure metals (in terms of their properties)

Answer 3

• Pure​ ​metals​ ​have​ ​a​ ​regular​ ​arrangement​ ​of​ ​equally​ ​sized​ ​positive​ ​metal ions​ ​surrounded​ ​by​ ​a​ ​sea​ ​of​ ​delocalised​ ​electrons.​ The ​ions​ ​are​ ​arranged regularly​ ​and​ ​are​ ​equal​ ​in​ ​size,​ ​the​ ​layers​ ​are​ ​able​ ​to​ ​slide​ ​over​ ​each​ ​other​ ​easily, Soft and malleable.
• Whereas in alloys, alloys​ ​are​ ​made​ ​from​ ​2​ ​or​ ​more​ ​different​ ​types​ ​of​ ​metals.​ ​The​ ​different​ ​sized atoms​ ​distort​ ​the​ ​layers​ ​in​ ​the​ ​structure,​ ​making​ ​it​ ​harder​ ​for​ ​them​ ​to​ ​slide​ ​over each​ ​other.​ ​​Alloys​ ​are​ ​harder​ ​than​ ​pure​ ​metals.

Question 4

We can put metals in order of their reactivity by investigating how well they react with water or hydrochloric acid. and the reduction of their oxides with carbon

Answer 4

Water/steam:
- Potassium: Reacts very violently with cold water
-Sodium: Reacts violently with cold water
-Calcium: No
-Magnesium: Reacts very slowly with water, but rapidly with steam
-Zinc: Only reacts when powdered and heated strongly in steam
Iron: Does not react with water, slowly with steam
Hydrogen: No reaction
Copper: No reaction

dilute hydrochloric acid

• Potassium: Very violently: very explosive
• Sodium: Very violently: explosive
• Calcium: Very rapid, lots of H+ produced
• Magnesium: Rapid bubbles of hydrogen produced steadily
• Zinc: Slow-bubbles of hydrogen produced slowly
• Iron: Slow reaction- some bubbles produced
• Hydrogen: No reaction
• Copper: No reaction
• Zinc, Iron, Hydrogen, Copper Oxides reduced by carbon
• the more reactive on the top (potassium, sodium, calcium etc) and the least reactive on the bottom (iron, hydrogen, copper). Only metals above hydrogen will react with water/steam and hydrochloric acid.

Question 5

The reactivity series as related to the tendency of a metal to form its positive ion

Answer 5

-When​ ​metals​ ​react​ ​with​ ​other​ ​substances,​ ​metal​ ​atoms​ ​form​ ​positive​ ​ions
-Reactivity​ ​of​ ​a​ ​metal​ ​is​ ​related​ ​to​ ​its​ ​tendency​ ​to​ ​form​ ​positive​ ​ions
-A​ ​more​ ​reactive​ ​metal​ ​can​ ​displace​ ​a​ ​less​ ​reactive​ ​metals​ ​from​ ​a​ ​compound (displacement reaction)​ ​e.g.
oxide​ ​or​ ​aqueous​ ​solution​ ​with​ ​the​ ​aqueous​ ​ions​ ​(think​ ​about​ ​how​ ​this​ ​is​ ​similar as​ ​well​ ​to​ ​halogens)

Question 6

The action of heat on the hydroxides, carbonates and nitrates of the listed metals

Answer 6

-Metal​ ​carbonate​ ​–(heat)->​ ​metal​ ​oxide​ ​+​ ​carbon​ ​dioxide
Calcium,​ ​sodium,​ ​magnesium​ ​and​ ​copper​ ​decompose​ ​in​ ​ this​ ​way
-Metal​ ​hydroxide​ ​–(heat)->​ ​metal​ ​oxide​ ​+​ ​steam
Zinc,​ ​iron,​ ​copper​ ​decomposePotassium,​ ​sodium,​ ​calcium,​ ​magnesium​ ​are​ ​too​ ​stable​ ​and​ ​therefore​ ​do not​ ​decompose​ ​in​ ​this​ ​way
-Metal​ ​nitrate​ ​–(heat)->​ ​metal​ ​oxide​ ​+​ ​nitrogen​ ​dioxide​ ​+​ ​ oxygen o Zinc,​ ​iron,​ ​copper
-Metal​ ​nitrate​ ​–(heat)->​ ​metal​ ​nitrite​ ​+​ ​oxygen
Potassium,​ ​sodium,​ ​calcium,​ ​magnesium

Question 7

unreactivity of aluminium in terms of the oxide layer which adheres to the metal

Answer 7

• Aluminium​ ​metal​ ​reacts​ ​with​ ​oxygen​ ​in​ ​the​ ​air​ ​to​ ​form​ ​Al​2O​ ​3,​ ​ ​aluminium​ ​oxide o This​ ​coats​ ​the​ ​surface​ ​of​ ​the​ ​aluminium​ ​and​ ​is​ ​very​ ​unreactive
• Therefore,​ ​it​ ​can​ ​prevent​ ​the​ ​aluminium​ ​metal​ ​from​ ​further​ ​oxidation

Question 8

order​ ​of​ ​reactivity​ ​from​ ​a​ ​given​ ​set​ ​of​ ​experimental​ ​results

Answer 8

less​ ​reactive​ ​metals​ ​will​ ​remain​ ​unchanged​ ​as​ ​they​ ​will​ ​not​ ​undergo reaction

Question 9

Ease in obtaining metals from their ores by relating the elements to the reactivity series

Answer 9

-gold, ​since​ ​it​ ​is​ ​very unreactive,​ ​it​ ​is​ ​found​ ​in​ ​the​ ​Earth​ ​as​ ​the​ ​metal​ ​itself
-But,​ ​most​ ​metals​ ​are​ ​found​ ​as​ ​compounds​ ​that​ ​require​ ​chemical​ ​reactions​ ​to extract​ ​the​ ​metal
-Metals​ ​less​ ​reactive​ ​than​ ​carbon:
Can​ ​be​ ​extracted​ ​from​ ​their​ ​oxides​ ​by​ ​reduction​ ​with​ ​carbon (​reduction​ ​involves​ ​the​ ​loss​ ​of​ ​oxygen)

Question 10

The extraction of zinc from zinc blende

Answer 10

-Zinc​ ​sulfide​ ​is​ ​turned​ ​into​ ​zinc​ ​oxide​ ​by​ ​heating very strongly (2ZnS + 3O2 → 2ZnO + 2SO2)
-Carbon burns in a blast of very hot air to form carbon dioxide: C + O2 → CO2
The carbon dioxide produced reacts with more coke to form carbon monoxide: CO2 + C → 2CO
The carbon monoxide is the reducing agent and reduces the zinc oxide to zinc: ZnO(s) + CO(g) →Zn(g) + CO2(g)

Question 11

Essential reactions in the extraction of iron from hematite

Answer 11

• Input Charge/ Load : Coke(carbon), Limestone, Fe2o3
• Hot​ ​air​ ​enters​ ​from​ ​bottom​ ​and​ ​goes​ ​to​ ​top​ ​of​ ​furnace
• Oxygen​ ​reacts​ ​with​ ​coke​ ​to​ ​form​ ​CO2​ (C(s) + O2(g) -> CO2(g)
• CO2 Reduced by carbon to Form CO: CO2(g) + C(s) -> 2CO(g)
• Reduction of Ore by CO: Fe2O3(s) + 3CO(g) -> 2 Fe(s) + 3CO2(g)
• Limestone added to remove impurities (Silica, SiO2): CaO(s) + SiO2(s) -> CaSiO3(l), Calcium silicate (CaSiO3) Forms slag

Question 12

The conversion of iron into steel using basic oxides and oxygen

Answer 12

• Carbon​ ​is​ ​removed​ ​from​ ​molten​ ​iron​ ​by​ ​blowing​ ​oxygen​ ​into​ ​it
• Oxygen​ ​reacts​ ​with​ ​carbon​ ​→​ ​carbon​ ​monoxide​ ​+​ ​carbon​ ​dioxide, Both​ ​gases​ ​escape​ ​from​ ​the​ ​iron

Question 13

aluminium is extracted from the ore bauxite by electrolysis

Answer 13

• Metals​ ​that​ ​are​ ​more​ ​reactive​ ​than​ ​carbon​ ​e.g​ ​aluminium​ ​are​ ​extracted by​ ​electrolysis​ ​of​ ​molten​ ​compounds.
• Metals​ ​that​ ​react​ ​with​ ​carbon​ ​can​ ​be​ ​extracted​ ​by​ ​electrolysis​ ​as​ ​well

Question 14

The extraction of aluminium from bauxite

Answer 14

1. Bauxite treated with sodium hydroxide to obtain pure Al2O3
   2.Aluminium oxide is dissolved in molten cryolite to decrease melting point of Al2O3 (means​ ​electrolysis​ ​can happen​ ​at​ ​a​ ​lower​ ​temperature)
   3.Mixture is electrolyzed with graphite electrodes
   Cathode: Aluminium Ions are discharged from solution
   -Al3+ + 3e- -> Al
   Anode: Oxides are discharged
   - C(s) + O2(g) -> CO2(g)
   -electrodes​ ​must​ ​be​ ​replaced​ ​regularly​ as carbon dioxide is formed, so they gradually burn away.

Question 15

Advantages and disadvantages of recycling metals

Answer 15

Advantages​ ​of​ ​recycling:
-Requires​ ​less​ ​energy​ ​to​ ​melt​ ​and​ ​remould​ ​metals​ ​than​ ​it​ ​does​ ​to​ ​extract new​ ​metals​ ​from​ ​their​ ​ores
-Fewer​ ​quarries​ ​and​ ​mines​ ​needed​ ​than​ ​to​ ​extract​ metals,​ ​so​ ​less​ ​noise and​ ​dust​ ​pollution
-Recycling​ ​allows​ ​for​ ​waste​ ​metals​ ​to​ ​be​ ​reused,​ ​saving​ ​money,​ ​helping the​ ​environment​ ​and​ ​the​ ​supply​ ​of​ ​valuable​ ​raw​ ​materials.
Disadvantages​ ​of​ ​recycling:
-Requires​ ​energy​ ​to​ ​transport​ ​metals​ ​to​ ​recycling​ ​centre
-metals​ ​must​ ​be​ ​sorted​ ​into​ ​types
- for​ ​different​ ​metals,​ ​the​ ​amount​ ​of​ ​energy​ ​saved​ ​varies

Question 16

Uses of aluminium

Answer 16

Used in:
– in the manufacture of aircraft because of its strength and low density
– in food containers because of its resistance to corrosion

Question 17

uses of zinc for galvanising and for making brass

Answer 17

Used in

• Galvanising: Zinc​ ​can​ ​be​ ​sacrificed​ ​to​ ​keep​ ​steel​ ​from​ ​rusting​. Galvanising, ​to​ ​coat​ ​iron​ ​or​ ​steel​ ​with​ ​a​ ​protective​ ​layer​ ​of​ ​zinc so Zinc​ ​is​ ​oxidised​ ​instead​ ​of​ ​the​ ​iron/steel
• Brass: Zinc​ ​is​ ​alloyed​ ​with​ ​copper​ ​to​ ​make​ ​brass

Question 18

uses of copper

Answer 18

• Copper​ ​is​ ​soft,​ ​easily​ ​bent,​ ​good​ ​conductor​ ​of​ ​electricity and heat
• Therefore,​ ​it​ ​is​ ​used​ ​in​ ​electrical​ ​wiring​ ​and​ ​in​ ​cooking​ ​utensils​ ​(pans)

Question 19

uses of mild steel and stainless steel

Answer 19

• Mild​ ​steel​ ​is tough,​ ​ductile,​ ​malleable,​ ​good​ ​tensile​ ​strength​ , used in car​ ​bodies​ ​& machinery
• Stainless ​​steel​​​​ (chromium ​​&​​ iron​​ alloy)​​, is resistant ​​to​​ corrosion​​ thus used in chemical​​ plants &​ ​cutlery

Question 20

You can change the properties of iron by the controlled use of additives to form steel alloys

Answer 20

-​chromium​ ​&​ ​nickel​ ​are​ ​mixed​ ​to​ ​make​ ​stainless​ ​steel,​ ​which​ ​is​ ​resistant​ ​to corrosion
-depending​ ​on​ ​the​ ​elements​ ​used​ ​in​ ​addition​ ​to​ ​iron​ ​to​ ​form​ ​steel
alloys,​ ​the​ ​properties​ ​will​ ​be​ ​different​,​ ​different​ ​uses
-Alloys​ ​will​ ​be​ ​harder​ ​than​ ​pure​ ​iron​ ​because​ ​the​ ​different​ ​sized​ ​metal​ ​ions​ ​disrupt​ ​the​ ​regular​ ​arrangement​ ​of​ ​layers​ ​of​ ​ions,​ ​preventing​ ​them sliding​ ​over​ ​each​ ​other​ ​as​ ​easily.​ ​The​ ​more​ ​different​ ​sized​ ​metal​ ​ions​ ​added​ ​to iron,​ ​the​ ​harder​ ​the​ ​alloy​ ​will​ ​be.