Question

Brass is an alloy of copper and zinc. varying the mass per- centages of the two metals produces brasses with different proper- ties. a brass called yellow zinc has high ductility and strength and is 34–37% zinc by mass. (a) find the mass range (in g) of copper in 185 g of yellow zinc. (b) what is the mass range (in g) of zinc in a sample of yellow zinc that contains 46.5 g of copper?

Answer 1

First step: The mass of zinc in the yellow zinc sample can be calculated with the help of percentage (given) in the sample. After that, mass of copper is determine by the subtracting the mass of zinc from the total mass of zinc in the given sample.

Thus,

Mass of zinc in 34% zinc sample = $185 g yellow zinc \times \frac{34 zinc}{100 yellow zinc}$

= $62.9 g$ zinc

Mass of zinc in 37% zinc sample = $185 g yellow zinc \times \frac{37 zinc}{100 yellow zinc}$

= $68.45 g$ zinc

Now,

mass of copper in 34% zinc sample =$185 g -62.9 g$

= $122.1 g \simeq 122 g$

mass of copper in 37% zinc sample = $185 g -68.45 g$

=$116.55 g \simeq 117 g$

Thus, the range of mass of copper is $117 g$ to  $122 g$

Second step:

34% zinc sample consist of 66% copper (100-34= 66%)

37% zinc sample consist of 63% copper (100-37=63%)

Mass of zinc = $(46.5 g copper) \times \frac{34 percent zinc}{66 percent copper}$

= $23.95 g\simeq 24 g$

Mass of zinc  =$46.5 g copper \times \frac{37 percent zinc}{63 percent copper}$

= $27.30 g\simeq 27g$

Thus, the range of mass of zinc is $24 g$ to  $27 g$