Calculate the quantity of pure gold in 100 g of an alloy of gold and copper The densitites of gold, - Science - Gravitation

Question

Calculate the quantity of pure gold in 100 g of an alloy of gold
and copper The densitites of gold, copper and the alloy are 19 9 g
/ cc ,9 g / cc and 16 g / cc respectively

Pradeep Ch · Accepted Answer

let the quantity of gold be x
therefore, quatity of copper be 100 - x

now,
density = mass/volume
therefore density of gold = 19 9 = x /v1
density of coper = 9 = (100 - x)/v2
density of alloy = 16 = 100/(v1 + v2) {since volume
occupied by both will be equal to the volume occupied by the
alloy}
therefore,
16( x/19 9 + 100/9 - x/9) = 100
therefore,
16(x/19 9 - x/9) = 100 - 1600/9
therefore,
16(19 9x - 9x)/19 9 x 9 =
700/9
therefore, 10 9x = 700 x 19 9 /16
=> x = 700 x 19 9/10 9 x 16
therefore,
x = 79 8 g

therefore,
quantity of gold is approximately 80g

hope it helps!!
cheers!!!
thumbs up plz

Calculate the quantity of pure gold in 100 g of an alloy of gold and copper.The densitites of gold, copper and the alloy are 19.9 g / cc ,9 g / cc and 16 g / cc respectively.