Question

Density of gold is 19.3 gm/cc and that of copper is 8.9 gm/cc. 10gm of gold and 10

gm of copper is mixed to form an alloy. The density of the alloy is

a) 10.4 gm/cc b) 11.4 gm/cc c) 12.4 gm/cc d) 9.4 gm/cc​

Answer 1

Answer:Hi!!!

The density of gold is Dau = 19.3 g/cc and that of copper Dcu = 8.9g/cc.

As mentioned in question,

you make a 20 g sample of this alloy, 10 g will be Au, 10 g will be Cu.

The total volume of the alloy will be 10 g Au/Dau + 10 g Cu/Dcu = 10/19.3 + 10/8.9 = 0.518134715 cc + 1.12359551 cc = 1.64173022 cc

The density of the alloy is its mass (20g) divided by its volume (1.64173022 cc) or 20/1.64173022 g/cc = 12.1822695 g/cc.(answer)

That is 12.4gm/cc (approximate)

Explanation:In general then, the equation to calculate density is 1/Dalloy = Mass Fraction Metal 1/Dmetal 1 + Mass Fraction Metal 2/Dmetal 2.

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