Question

The zinc within a copper-plated penny will dissolve inhydrochloric acid if the copper coating is filed down in severalspots (so that the hydrochloric acid can get to the zinc). Thereaction between the acid and the zinc is as follows: 2H+(aq)+Zn(s)?H2(g)+Zn2+(aq).
When the zinc in a certain penny dissolves, the totalvolume of gas collected over water at 25 ?Cwas 0.957L ata total pressure of 748 mmhg

Whatmass of hydrogen gas was collected

mmHg