Modern pennies are composed of zinc coated with copper. Astudent determines the mass of a penny to be 2.480 g and then makesseveral scratches in the copper coating (to expose the underlyingzinc). The student puts the scratched penny in hydrochloric acid,where the following reaction occurs between the zinc and the HCl(the copper remains undissolved):
Zn(s)+2HCl(aq)→H2(g)+ZnCl2(aq)
The student collects the hydrogen produced over water at 25 ∘C. Thecollected gas occupies a volume of 0.903 L at a total pressure of786 mmHg .
Calculate the percent zinc in the penny. (Assume thatall the Zn in the penny dissolves.)
