Question

The British gold sovereign coin is an alloy of gold and copperhaving a total mass of 7.988 g, and is 22-karat gold. (a) Find the mass of gold in the sovereign in kilograms using thefact that the number of karats = 24 Image for The British gold sovereign coin is an alloy of gold and copperhaving a total mass of 7.988 g, and is 22-karat (massof gold)/(total mass). kg (b) Calculate the volumes of gold and copper, respectively, used tomanufacture the coin. volume of gold m3 volume of copper m3 (c) Calculate the density of the British sovereign coin. kg/m3

Answer 1

Part A:

In 22-karat gold, mass of gold will be:

Total mass of alloy = 7.988 gm = 0.007988 kg

Mass of gold = (22/24)*total mass = (22/24)*0.007988

Mass of gold = 0.007322 kg

Part B:

Volume of gold = Mass/density

density of gold = 19320 kg/m^3

So,

Volume of gold = 0.007322/19320 = 3.790*10^-7 m^3

Volume of copper will be:

Mass of copper = Total mass - mass of gold = 7.988 - 7.322 = 0.666 g = 0.000666 kg

Density of copper = 8960 kg/m^3

Volume of copper = 0.000666/8960 = 7.433*10^-8 m^3

Part C.

Density of coin will be:

Density = Mass/Volume

Mass of coin = 7.988 gm = 0.007988 kg

Total volume of coin = 3.790*10^-7 + 7.433*10^-8 = 4.5333*10^-7 m^3

So,

density = Mass/Volume = 0.007988/(4.5333*10^-7) = 17620.7 kg/m^3

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