Intermediate Topic 682 of 1102 Inorganic Chemistry
Gold and Platinum
Noble metals resistant to corrosion, used in jewelry and catalysis.
In-depth explanation of Gold and Platinum
Gold and platinum are noble metals that resist oxidation and corrosion, because their standard electrode potentials are high and they do not readily form oxides. Gold dissolves only in aqua regia, a mixture of concentrated hydrochloric and nitric acids in about a 3 to 1 ratio, and in alkaline cyanide solution in the presence of oxygen. Cyanide leaching of gold ore is based on this second reaction. Platinum is also resistant to acids but dissolves in aqua regia. Gold is used in jewellery and electronics because it is malleable and does not tarnish. Platinum is an important catalyst, used in catalytic converters and in the Ostwald process.
Going deeper: Gold and Platinum
Key ideas: Both are noble metals with high positive reduction potentials (Au3+ +1.5 V) and resist oxidation by acids; dissolve only in aqua regia, forming AuCl4- or PtCl6 2- because chloride complexation lowers the potential and nitric acid oxidizes. Gold is the most malleable, purity in carats: 24 carat is pure and 18 carat is 75 percent. Pt is used in catalytic converters, catalysts and electrodes, and cisplatin. Gold dissolves in cyanide with air: the cyanide process.
Common mistakes and connections: Students think aqua regia is simply a stronger acid; it is a combination of oxidation and complexation. Gold is not unreactive toward halogens or cyanide. Platinum group metals absorb hydrogen. Links to reduction potentials, complex formation, cisplatin and catalysts.
Visualization of Gold and Platinum
Standard reduction potentials: gold and platinum have very high values, so they resist oxidation and need aqua regia or cyanide with O2 to dissolve. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Gold is extracted from crushed ore by leaching with dilute sodium cyanide solution in the presence of air.
Frequently asked questions about Gold and Platinum
What is Gold and Platinum?
Noble metals resistant to corrosion, used in jewelry and catalysis.
Is Gold and Platinum a beginner, intermediate or advanced topic?
Gold and Platinum is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Gold and Platinum?
Study these earlier topics in Inorganic Chemistry first: Chromium Compounds, Potassium Permanganate, Silver Chemistry.
What comes after Gold and Platinum?
The next topics in Inorganic Chemistry are Mercury and Lanthanides.
Can I practise Gold and Platinum with quizzes?
Yes. The interactive lesson includes a self-check question on Gold and Platinum, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Gold and Platinum fits in Inorganic Chemistry
Gold and Platinum is topic 67 of 113 in Inorganic Chemistry.