When the brass sample was dissolved in 8 M nitric acid in a flask and then transferred to the 50.0 ml volumetric flask, suppose some of the mixture was spilled onto the table top. Would the percent copper found experimentally be higher, lower, or equal to the actual percent copper in the brass sample?
Brass is an alloy of copper and zinc. I'm assuming that the 8M HNO3 is reacting with the zinc and leaving the copper untouched. You are then diluting the acid/Zn(NO3)2 solutuion to 50ml and determining the amount of zinc present in this sample. If some of this was spilled it would give you an incorrect low level of zinc. This would suggest that, given that the zinc reading is low that copper would be erroneously found to be higher than it actually is. eg, if the actual composition was 45:55, zinc:copper, it may appear that the zinc was actually 42%, suggesting copper was 58%.... higher than the actual value.
