Question

brass weighs 12.9 grams in air.when completely immersed in water it weighs 11.3 gram.what is the mass of copper in the alloy. relative densities of copper is 8.9 and of zinc is 7.1

Answer 1

Weight of alloy in air = 12.9 g

Weight of alloy in water = 11.3 g

Weight of water displaced = 12.9-11.3 = 1.6g

Volume of alloy = 1.6cc

If alloy contains x g Cu and (12.9-x) g zinc then

(x / 8.9)+[(12.9-x) / 7.1] = 1.6

After solving it, we get the value of x

x = 7.61g