Gold

Shaun Lynn

Scientific Skills

J9106574

Gold

Occurrence & Extraction of Gold

Gold has an abundance of 4ppb of the Earth’s crust

Also found alloyed to other metals such as silver

Occurrence & Extraction of Gold

Nuggets Grains Microscopic

2/3 world’s output .

Purification of Gold

Smelting

Cyanidation

4Au + 8NaCN +O2 +H2O 4[NaAu(CN)2] +4H2O

Reaction With Air & Water

• Chemically unreactive• Does not react with air or with water

Electron configuration is [Xe] 4f14 5d10 6s1D orbital is saturated chemical unreactivityCrystal lattice structure is face centred cubic Surface structure with limited freedom for bonding Good for adsorption

Reaction With AcidsAlso unaffected by acids and basesExcept:

Aqua Regia(3:1 mixture of hydrochloric & nitric acid)

Reaction With Acids• Gold + Aqua Regia

• This could be taken one step further to make chloroauric acid (liquid gold)

Au (s) + 3 NO3- (aq) + 6 H+ (aq) → Au3+ (aq) + 3 NO2 (g) + 3 H2O (l)

Au3+ (aq) + 4 Cl- (aq) → AuCl4- (aq)

Oxidation States• Gold has an oxidation state of +1 and +3

• However, it has the ability to reach a maximum oxidation number of +5

Such as Gold(v)pentaflouride!

Oxidation States• In an atmosphere of oxygen and fluorine, at

400°C at 8 atmospheres:

• This will decompose at 180°C :

2 Au + 2 O2 + 6 F2 → 2 O2AuF6

2 gold dioxyflouride salt

O2AuF6 → Au2F10 + 2 O2 + F2

Octahedralwith Bi dentate fluoride bonds

Gold(v) pentafluoride

UsesCatalyst

• Heterogeneous• Catalytic Converter • Adsorbs O2 and CO and allow CO2 to form.

UsesAs a catalyst:• Remove bad smells and toxins from the atmosphere• Glucose to Gluconic acid• Vinyl acetate monomers

In medicine:• Used to treat arthritis since 1929• Prostate cancer treatment

Also:• Fine Jewellery • Currency is dependent upon gold

Interesting Compound!• Gold also has an oxidation state of -1 to form an Au-1 anion

• This enables gold to react with metals with an oxidation state of +1, to form ionic compounds with non metalic properties.

E.g.• CsAu Cesium Auride

has a low melting point of 480°C classified as a semi conductor

References• Chloroauric Acid (Liquid gold) : Molecule of the Day. (2010, March 01). Retrieved march 01, 2010, from

Science Bloggs: http://scienceblogs.com/moleculeoftheday/2007/08/chloroauric_acid_liquid_gold.php• Nobel Foundation. (2010, March 01). The Nobel Prize Medals and the Medal for the Prize in Economics.

Retrieved March 01, 2010, from nobelprize.org: http://nobelprize.org/nobel_prizes/medals/• Unknown. (2010, February 26). Gold element facts. Retrieved February 26, 2019, from Chemicool:

http://www.chemicool.com/elements/gold.html• Unknown. (2010, February 2010). Gold Elements Facts. Retrieved february 28, 2010, from Chemicool:

http://www.chemicool.com/elements/gold.html• Walker, J. (2010, march 08). What Gives Gold that Mellow Glow? Retrieved March 08, 2010, from

Fourmilab Switzerland: http://www.fourmilab.ch/documents/golden_glow/• Winter, M. (2010, February 28). Table of the Elements | Gold | chemical reaction data. Retrieved

February 28, 2010, from WebElements : http://www.webelements.com/gold/chemistry.html• Housecroft, C. E. (2006). Chemistry An introduction to Organic, Inorganic and Physical Chemistry (Third

Edition ed.). harlow, Essex, England: Pearson Education Limited.• World Gold Council. (n.d.). Properties. Retrieved march 07, 2010, from World Gold Council:

http://www.utilisegold.com/uses_applications/properties_of_gold/• World Gold Council. (n.d.). Uses and applications. Retrieved march 07, 2010, from World Gold Council:

http://www.utilisegold.com/uses_applications/properties_of_gold/