Modern pennies are composed of zinc coated with copper. A student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). 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) + 2 HCl(aq) → H2(g) + ZnCl2(aq)
The student collects the hydrogen produced over water at 25 °C. The collected gas occupies a volume of 0.899 L at a total pressure of 791 mmHg. Calculate the percent zinc (by mass) in the penny. (Assume that all the Zn in the penny dissolves.)
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Based on our data, we think this problem is relevant for Professor Morkowchuk's class at UVA.
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Our data indicates that this problem or a close variation was asked in Chemistry: A Molecular Approach - Tro 2nd Edition. You can also practice Chemistry: A Molecular Approach - Tro 2nd Edition practice problems.