A piece of brass weighs 12.9 g in air. When completely immersed in wat

1.	A piece of brass weighs 12.9 g in air. When completely immersed in water it weighs 11.3 g. What is mass of copper contained in the alloy?Relative density of copper and zinc are 8.9 and 7.1 respectively.
Answer» Mass of brass in air = 12.9 g Mass of brass in water = 11.3 g Mass of water displaced = 13.9 - 11.3 = 1.6 g relative density of copper = 8.9 Relative density of zinc = 7.1 Relative density = density of substance/ density of water Density of copper = 8.1 g/cc Which can be written as Mass/ Volume = 8.1 g/cc Similarly Density of zinc = 7.9 g/cc and volume of alloy = 1.6 cc Let x be the mass of copper is alloy Hence, alloy contains the substances Volume of alloy = Volume of copper + Volume of zinc 1.6 = x/8.9 + (12.9 - x)/7.1 1.6 = 7.1x + 8.9(12.9 - x) x = 7.614 g Mass of copper is 7.614 g.

A piece of brass weighs 12.9 g in air. When completely immersed in water it weighs 11.3 g. What is mass of copper contained in the alloy?Relative density of copper and zinc are 8.9 and 7.1 respectively.

Answer»

Mass of brass in air = 12.9 g

Mass of brass in water = 11.3 g

Mass of water displaced = 13.9 - 11.3 = 1.6 g

relative density of copper = 8.9

Relative density of zinc = 7.1

Relative density = density of substance/ density of water

Density of copper = 8.1 g/cc

Which can be written as Mass/ Volume = 8.1 g/cc

Similarly Density of zinc = 7.9 g/cc

and volume of alloy = 1.6 cc

Let x be the mass of copper is alloy

Hence, alloy contains the substances

Volume of alloy = Volume of copper + Volume of zinc

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

1.6 = 7.1x + 8.9(12.9 - x)

x = 7.614 g

Mass of copper is 7.614 g.

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