Batteries used in watches contain mercury(II) oxide. As the current flows, mercury(II) oxide is reduced to mercury according to the following reaction: HgO(s) + H₂O( $\ell$ ) + 2 e^- ? Hg( $\ell$ ) + 2 OH^-(aq)
If 2.3 × 10^-5 amperes flows continuously for 1200 days, calculate the mass of mercury, Hg( $\ell$ ) , produced.

Question

Batteries used in watches contain mercury(II) oxide. As the current flows, mercury(II) oxide is reduced to mercury according to the following reaction: HgO(s) + H₂O(

\ell

) + 2 e^- ? Hg(

\ell

) + 2 OH^-(aq)
If 2.3 × 10^-5 amperes flows continuously for 1200 days, calculate the mass of mercury, Hg(

\ell

) , produced.

Quizplus · Accepted Answer

The correct answer is A.The mass of mercury produced can be calculated using Faraday's law of electrolysis:$$m = \frac{ItM}{nF}$$where:* m is the mass of the substance produced (in grams)* I is the current (in amperes)* t is the time (in seconds)* M is the molar mass of the substance (in grams per mole)* n is the number of electrons transferred per mole of substance* F is the Faraday constant (96,485 coulombs per mole)In this case, we have:* I = 2.3 × 10^-5 amperes* t = 1200 days = 103,680,000 seconds* M = 200.59 g/mol* n = 2* F = 96,485 coulombs per moleSubstituting these values into the equation, we get:$$m = \frac{(2.3 	imes 10^{-5} 	ext{ A})(103,680,000 	ext{ s})(200.59 	ext{ g/mol})}{2(96,485 	ext{ C/mol})}$$$$m = 2.5 	ext{ g}$$Therefore, the mass of mercury produced is 2.5 grams.

Batteries Used in Watches Contain Mercury(II) Oxide ℓ\ellℓ ) + 2 E- ? Hg

Batteries Used in Watches Contain Mercury(II) Oxide $\ell$ ) + 2 E^- ? Hg