C7 Reactivity

C7 Reactivity

Reduction and Oxidation

Oxidation Is Loss Reduction Is Gain

Reduction is : 1. Loss of oxygen (covalent bonds)

2. gain of electron (ionic)

The reduced compound is an oxidizing agent

Oxidation is : 1. Gain of oxygen (covalent bonds)

2. loss of electron (ionic)

The oxidized compound is a reducing agent

 

Reactivity with Oxygen

Oxidation reactions – Cu + O2 → CuO, glow + slice flame

Mg + O2 → MgO white flames

Combustion reactions – CnHn + O2 → water + CO2 flames and stuff

 

Reactivity series

K←Na←Li←Ca←Mg←Al←C←Zn←Fe←H←Cu←Ag←Au

Possibly nicer livers can magnetize almonds cars,

zero-fee hype cures silvery golds

 

Metal extraction

Ore is economically viable containing metal rocks. Rock contains metals but not that worthwhile.

1. If metal ore is less reactive than carbon…
   1. Reduce metal with carbon to extract.
2. If it is more reactive
   1. Use electrolysis to split ions.

Alloys are formed to merge several desirable qualities of the different metals. Since lattice structure is disrupted by impurities, boiling point decreases as bonds are weaker.

 

Electrolysis

Electricity pass through electrodes to extract metals. Cations are at cathode and anions go to anode. Electrolyte is the solution that conducts electricity.

Half equations:

Cations: Pb2+ + 2e– → Pb

AnionsL 2Cl– → Cl2 + 2e–

1. 1. Separating seawater: Aqueous sodium hydroxide, hydrogen at cathode and chlorine at anode, sodium hydroxide is leftover – liquid NaCl won’t have leftovers.
   2. Industrial uses include: chlorine for swimming pool disinfectant and cleaning products, sodium hydroxide for stock chemical (strong alkali) and soap, hydrogen for haber process and margarine.
   3. Separating aluminum oxide: Al2O3, aluminum ore called bauxite, can be used to extract aluminum which is lightweight resistant to corrosion and used in airplane and bikes. Cryolite added to lower melting point. Al sinks to the bottom, produces aluminum and oxygen.

 

• molten lead(II) bromide, lead at cathode and bromine at anode

• aqueous copper chloride – copper at cathode and chlorine at anode

• dilute sulfuric acid – hydrogen at cathode and oxygen at anode

• Generally: metals or hydrogen form at cathode and non-metals form at anode.

 

Electrodes can be active or inert. Inert electrodes like graphite are not involved in the reaction and actibe electrodes are involved in reaction. Such as copper plating. Anode will become thinner and cathode thicker, and hence it is used to plate objects and remove impurity, electrolyte usually contains the same ion as anode.

Hoffman Voltameter is used to collect gas from electrolysis, such as water.

 

Blast furnace

Used to extract iron.

1. Add materials: hematite, coke(impure carbon as reducing agent), limestone to remove impurities
2. Make the reducing agent stronger: Carbon must become carbon monoxide
   1. C + O2 → CO2
   2. CO2 + C → CO
3. Reduce the iron:
   1. Fe2O3 + 3CO → 2Fe + 3CO2,
4. Remove impurities
   1. CaCO3 → CaO + CO2
   2. CaO + SiO2 (sand) → CaSiO3 (slag, used in road building, neutralizsation reaction)
5. 1000C and 2000C degrees

 

Rust

Rust is the specific corrosion of iron by oxidation to iron (3) oxide. Salt speeds up rusting and both oxygen and water are needed to produce hydrated iron oxide in a redox reaction.

Surface protection means covering iron to stop water/oxygen from entering, using oil, paint and wax. Specifically, galvanizing means coating with zinc.

Sacrificial protection puts a metal attachment of metals more reactive than iron like zinc and magnesium so water and air reacts with it first.