A piece of zinc of mass 5.0 g is dropped into a beaker of dilute hydrochloric ac

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Explanation / Answer

First write the balanced chemical equation:

ZN + 2 HCl = ZNCl2 + H2

Work is: (-Pressure * Change in Volume). Since we will be working with gases, we need to find the number of moles of Hydrogen produced.

(5 g Zn/ 1) * (1 mol Zn / 65.38 g Zn) * (1 mol H2 / 1 mol Zn) = 0.07647mol H2.

PV = nRT
(1 atm)(V) = (0.0764 mol)(0.0821 L*atm/mol*K)(296K)
V = 1.8584L H2.

Work = -Pressure * Change in Volume
Work = -1 * 1.8584
Work = -1.8584 J
The sign in negative, indicating that energy has left the system (work has been done on the surroundings).

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