Question

Determine the quantity of pure gold in 50 grams of an alloy of pure gold and copper density of gold Copper and alloy are 19 gram centimetre cube 9 gram centimetre cube and 16 gram centimetre cube respectively

Answer 1

Let x be the quantity of gold than 50-x will be the quantity of pure copper

Density = Mass/Volume

Volume of gold in x gm of gold V1 = Mass / Density = x/19

Volume of copper in 50-x gm of copper V2 = Mass / Density =(50-x)/9

V = V1 + V2

Volume of 50 gm alloy V = Mass/Density= 50/16

V = V1 + V2

50/16 = x/19 + (50-x)/9

50*9*19 = 16*(9x+950-19x)

8550 = -160x +15200

160x = 6650

x = 41.56 gm

Answer : 41.56 gm of gold