Answer to Question #70653 in General Chemistry for Bailey

Question

The zinc in a copper-plated penny will dissolve in hydrochloric acid if the copper coating is filed down in several spots (so that the hydrochloric acid can get to the zinc). The reaction between the acid and the zinc is: 2H+(aq)+Zn(s)→H2(g)+Zn2+(aq).
When the zinc in a certain penny dissolves, the total volume of gas collected over water at 25 ∘C was 0.949 L at a total pressure of 758 mmHg .What mass of hydrogen gas was collected?

Answer 1

The amount of collected hydrogen: (0.949 L)/(22.4 L/mol) = 0.0424 mol
Molar mass of hydrogen: 2.016 g/mol
Therefore, mass of hydrogen: 0.0424 mol ∙ 2.016 g/mol = 0.0855 g