Question 206901
A. "97.5 percent zinc and 2.5 percent copper by mass"
___ mass ratio is ... 97.5% : 2.5% ... or ... 39 : 1 ... or ... 39


B. density is the ratio of mass to volume ___ so to find volume; divide mass by density
___ using the result from A ___ volume ratio is ... (39 / 7.13) : (1 / 8.96) ... or ... 49.01 (approx)


C. (mass of copper) / (density of copper) = volume of copper
___ (mass of zinc) / (density of zinc) = volume of zinc
___ (volume of copper) + (volume of zinc) = .35


let x = "mass of copper" ___ (x / 8.96) + ((3.1 - x) / 7.13) = .35


multiplying by (8.96)(7.13) ___ 7.13x + 27.78 - 8.96x = 22.36 (approx)


-1.83x = -5.42 ___ x = 2.96 g (approx)