Note on Gold
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Symbol: Au
Atomic No: 79
Atomic Weight: 197.2
Valency: 1 and 3
Electronic configuration: 1s2,2s2,2p6,3s2,3p6,3d10,4s2,4p6,4d10,4f14,5s2,5p6,5d10,6s1
Position in the periodic table: Gold is a soft, lustrous yellow metal. It is a 'd' block transition element in the periodic table. It belongs to period 6 and group IB.
Physical properties
- Gold possesses a lustrous yellow color.
- It has a melting point 1063°C and boiling point of 2610°C
- It is a heavy metal with specific gravity 19.3.
- It is a good conductor of heat and electricity.
- It is less reactive metal.
Chemical properties of gold
- Reaction with acid:
Gold is a noble metal and has no action with water, air, alkalis and acids. But it dissolves in aqua regia (3:1 ratio of conc. HCl and conc. HNO3) to give gold chloride, nitrosyl chloride and water.
2Au + 3HNO3 + 9HCl → 3NOCl + 6H2O + 2AuCl3
Uses of gold
- It is used for making jewelry, coins and medals.
- It is used for making gold leaf electroscope.
- It is used for making alloys.
- Gold is a soft, lustrous yellow metal. It is a 'd' block transition element in the periodic table. It belongs to period 6 and group IB.
- The physical properties of gold are; it possesses a lustrous yellow color, good conductor of heat and electricity, less reactive metal melting point is 10630C and boiling point is 26100C.
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Very Short Questions
The mixture of conc. Nitric acid and hydrochloric acid in the ratio 1:3 is called aqua-regia. The chemical reaction between conc. Sulphuric acid and silver is: 2Ag + 2H2SO4 → Ag2SO4 + SO2 + 2H2O
Aqua-regia is the mixture of concentrated nitric acid and hydrochloric acid in 1:3 ratio. The chlorine found in aqua-regia can dissolve gold.
When gold is reacted with aqua-regia, gold chloride is formed. 2Au + 3HNO3 + 9HCl → 3NOCl + 6H2O + 2AuCl3
Gold is found in pure state in nature but not the iron because gold is un-reactive metal, so it does not react with other element in normal condition but iron is reactive metal so it reacts with atmospheric oxygen in presence of moist (water) to form oxide.
When gold is heated with chlorine, it gives gold chlorine. 2Au + 3Cl2 → 2AuCl3
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What is the Latin name of Gold?
Aurum
Argentum
Plumbum
Natrium
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Which of the following is not the property of gold?
It is least reactive metal.
It possesses lustrous yellow colour.
It's melting point is 960C and boiling point is 1955C
It is a heavy metal with a specific gravity of 19.3.
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The atomic number of gold is ______.
75
79
47
78
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Gold reacts with halogens to form their corresponding ______.
Alkali cyanide
Aqua regia
Sulphides
Halides
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What is Aqua regia?
2:1 ratio of conc.HCL and NaCL
3:1 ratio of conc. HCL and HNO3
2:1 ratio of conc. HCL and HNO3
3:1 ratio of conc.HCL and NaCL
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Which one of the following is the use of gold?
It is used for manufacturing dyes.
It is used in photography.
It is used for making electric wire.
It is used for electroplating.
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Which one of the following is the ore of gold?
Haematite
Magnesite
Cobaltite
Alluvial
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