Saved Bookmarks
| 1. |
A piece of brass weighs 12.9 g in air. Brass is an alloy of Zinc and copper. When completely immersed in water it weighs11.3 g. What is the mass of copper contained in the alloy?Specific gravity of zinc and copper are 7.1 and 8.9respectively. |
|
Answer» 7.61 gExplanation:LET : Mass of copper in the alloy = m= > Mass of zinc = ( 12.9 - m ) g= > Volume of copper = m / 8.9 Volume of zinc = ( 12.9 - m ) / 7.1Total volume of the alloy = m / 8.9 + ( 12.9 - m ) / 7.1 .... ( i ) = > Apparent loss of weight of alloy = 12.8 - 11.3 = 1.6 g wtVolume of water DISPLACED by alloy = 1.6 / 1 = 1.6 cm³ ..... ( II ) From ( i ) and ( ii ) we get : m / 8.9 + ( 12.9 - m ) / 7.1 = 1.6= > 7.1 m + 8.9 ( 12.9 - m ) = 1.6 × 8.9 × 7.1= > m = 7.61 gTherefore , mass of copper contained in the alloy is 7.61 g. |
|