An electrolytic cell produces aluminum from \(\mathrm{Al}_{2} \mathrm{O}_{3}\) at the rate of ten kilograms a day. Assuming a yield of \(100 \%\), (a) how many moles of electrons must pass through the cell in one day? (b) how many amperes are passing through the cell? (c) how many moles of oxygen \(\left(\mathrm{O}_{2}\right)\) are being produced simultaneously?

Short Answer

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Question: Calculate the amperes passing through the electrolytic cell and the moles of oxygen gas produced simultaneously when 10 kg of aluminum is produced from aluminum oxide (Al2O3) in one day. Answer: Approximately 1272.74 amperes are passing through the electrolytic cell, and 370.64 moles of oxygen gas are produced simultaneously.

Step by step solution

01

Calculate moles of aluminum produced

To convert the mass of aluminum produced into moles, we will use the molar mass of aluminum. The molar mass of aluminum (\(\mathrm{Al}\)) is approximately 26.98 g/mol. So, we have: \(10\,\text{kg} \cdot \frac{1000\,\text{g}}{1\,\text{kg}} \cdot \frac{1\,\text{mol}}{26.98\,\text{g}} \approx 370.64\,\text{moles}\) of \(\mathrm{Al}\) So, the cell produces approximately 370.64 moles of aluminum per day.
02

Calculate moles of electrons required

Next, we need to recall the balanced redox reaction for aluminum production. In this case, we have: \(\mathrm{Al}^{3+} + 3\,\text{e}^- \rightarrow \mathrm{Al}\) Thus, three moles of electrons are required for each mole of aluminum produced. So, the moles of electrons required for this process are: \(370.64\,\text{moles}\,\mathrm{Al} \cdot \frac{3\,\text{moles\,electrons}}{1\,\text{mole\,Al}} = 1111.93\,\text{moles\,electrons}\) Therefore, 1111.93 moles of electrons must pass through the cell in one day.
03

Calculate the current (amperes) passing through the cell

Now, we can calculate the current passing through the cell. We know that current is measured in amperes (A), and one ampere is equal to one coulomb of charge per second: \(1\,\text{A} = 1\,\frac{\text{C}}{\text{s}}\) We know that the charge of one mole of electrons is equal to Avogadro's number times the elementary charge. So we have: \(1\,\text{mole}\,\text{electrons=}6.022 \times 10^{23}\,\text{electrons} \cdot 1.6 \times 10^{-19}\,\text{C} \approx 96485\,\text{C}\) Thus, to find the current, we need to convert the moles of electrons per day to coulombs per second: \(\frac{1111.93\,\text{moles\,electrons}}{1\,\text{day}} \cdot \frac{96485\,\text{C}}{\text{mole}\,\text{electrons}} \cdot \frac{1\,\text{day}}{86400\,\text{s}} \approx 1272.74\,\text{A}\) So, approximately 1272.74 amperes are passing through the cell.
04

Calculate moles of oxygen produced simultaneously

Lastly, we will find the moles of oxygen (\(\mathrm{O}_{2}\)) produced simultaneously. The balanced redox reaction for oxygen production is: \(2\,\mathrm{O}^{2-} \rightarrow \mathrm{O}_{2} + 4\,e^-\) We can see from this reaction that two moles of oxygen ions (\(\mathrm{O}^{2-}\)) produce one mole of oxygen gas (\(\mathrm{O}_{2}\)). Since aluminum oxide contains two moles of oxygen ions for each mole of aluminum ions, we can use the moles of aluminum produced to find the moles of oxygen produced: \(370.64\,\text{moles}\,\mathrm{Al} \cdot \frac{1\,\text{mole}\,\mathrm{O}_{2}}{1\,\text{mole}\,\mathrm{Al}} = 370.64\,\text{moles}\,\mathrm{O}_{2}\) Thus, 370.64 moles of oxygen gas are produced simultaneously by the electrolytic cell.

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Most popular questions from this chapter

An alloy made up of tin and copper is prepared by simultaneously electroplating the two metals from a solution containing \(\mathrm{Sn}\left(\mathrm{NO}_{3}\right)_{2}\) and \(\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}\). If \(20.0 \%\) of the total current is used to plate tin, while \(80.0 \%\) is used to plate copper, what is the percent composition of the alloy?

Consider a voltaic cell at \(25^{\circ} \mathrm{C}\) in which the following reaction takes place. $$ 3 \mathrm{O}_{2}(g)+4 \mathrm{NO}(g)+2 \mathrm{H}_{2} \mathrm{O} \longrightarrow 4 \mathrm{NO}_{3}^{-}(a q)+4 \mathrm{H}^{+}(a q) $$ (a) Calculate \(E^{\circ}\) (b) Write the Nernst equation for the cell. (c) Calculate \(E\) under the following conditions: \(\left[\mathrm{NO}_{3}{ }^{-}\right]=0.750 M\), \(P_{\mathrm{NO}}=0.993 \mathrm{~atm}, P_{\mathrm{O}_{2}}=0.515 \mathrm{~atm}, \mathrm{pH}=2.85\)

Consider the reaction below at \(25^{\circ} \mathrm{C}\) : $$ 3 \mathrm{SO}_{4}{ }^{2-}(a q)+12 \mathrm{H}^{+}(a q)+2 \mathrm{Cr}(s) \longrightarrow 3 \mathrm{SO}_{2}(g)+2 \mathrm{Cr}^{3+}(a q)+6 \mathrm{H}_{2} \mathrm{O} $$ Use Table \(18.1\) to answer the following questions. Support your answers with calculations. (a) Is the reaction spontaneous at standard conditions? (b) Is the reaction spontaneous at a \(\mathrm{pH}\) of \(3.00\) with all other ionic species at \(0.100 \mathrm{M}\) and gases at \(1.00\) atm? (c) Is the reaction spontaneous at a pH of \(8.00\) with all other ionic species at \(0.100 \mathrm{M}\) and gases at \(1.00 \mathrm{~atm}\) ? (d) At what \(\mathrm{pH}\) is the reaction at equilibrium with all other ionic species at \(0.100 \mathrm{M}\) and gases at \(1.00 \mathrm{~atm}\) ?

For the cell $$ \mathrm{Zn}\left|\mathrm{Zn}^{2+}\right| \mathrm{Cu}^{2+} \mid \mathrm{Cu} $$ \(E^{\circ}\) is \(1.10 \mathrm{~V}\). A student prepared the same cell in the lab at standard conditions. Her experimental \(E^{\circ}\) was \(1.0 \mathrm{~V}\). A possible explanation for the difference is that (a) a larger volume of \(\mathrm{Zn}^{2+}\) than \(\mathrm{Cu}^{2+}\) was used. (b) the zinc electrode had twice the mass of the copper electrode. (c) \(\left[\mathrm{Zn}^{2+}\right]\) was smaller than \(1 M\). (d) \(\left[\mathrm{Cu}^{2+}\right]\) was smaller than \(1 M\). (e) the copper electrode had twice the surface area of the zinc electrode.

Consider a voltaic cell at \(25^{\circ} \mathrm{C}\) in which the following reaction takes place. $$ 3 \mathrm{H}_{2} \mathrm{O}_{2}(a q)+6 \mathrm{H}^{+}(a q)+2 \mathrm{Au}(s) \longrightarrow 2 \mathrm{Au}^{3+}(a q)+6 \mathrm{H}_{2} \mathrm{O} $$ (a) Calculate \(E\). (b) Write the Nernst equation for the cell. (c) Calculate \(E\) when \(\left[\mathrm{Au}^{3+}\right]=0.250 \mathrm{M},\left[\mathrm{H}^{+}\right]=1.25 \mathrm{M},\left[\mathrm{H}_{2} \mathrm{O}_{2}\right]=\) \(1.50 M\)

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