Question Video: Identifying Which Substance Is Produced at the Cathode in the Electrolysis of Aqueous Copper(II) Chloride | Nagwa Question Video: Identifying Which Substance Is Produced at the Cathode in the Electrolysis of Aqueous Copper(II) Chloride | Nagwa

Question Video: Identifying Which Substance Is Produced at the Cathode in the Electrolysis of Aqueous Copper(II) Chloride Chemistry • Third Year of Secondary School

Copper metal is deposited at the cathode during the electrolysis of molten copper(II) chloride (CuCl₂ (l)). What substance is produced at the cathode during the electrolysis of aqueous copper(II) chloride?

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Video Transcript

Copper metal is deposited at the cathode during the electrolysis of molten copper(II) chloride, CuCl2, liquid. What substance is produced at the cathode during the electrolysis of aqueous copper(II) chloride? (A) Oxygen gas, (B) hydrogen gas, (C) copper metal, (D) steam, (E) chlorine gas.

Our question asks us to determine the product of an electrolysis reaction involving aqueous copper(II) chloride. We can answer this question using our knowledge of the reactivity series and the electrolysis of salt solutions as opposed to the electrolysis of molten solutions. The reactivity series is a ranking of common metals based upon their reactivity. In a typical reactivity series containing metal elements, we often find hydrogen, a nonmetal, that is used as a reference element to better understand the reactivity of the metals. Typically, metals that are above hydrogen in the series are highly reactive, while metals below hydrogen are quite unreactive.

We can use this information to help determine which products will form at the cathode of an electrolysis reaction of a salt solution. In a reactivity series, any metal that is above hydrogen, meaning it is more reactive, will produce hydrogen gas at the cathode of a reaction when the electrolyte is an aqueous solution. Any element below hydrogen will instead produce the pure elemental form of the metal at the cathode.

Our question tells us that the product that forms at the cathode from electrolysis reaction of a molten salt solution of copper(II) chloride is pure elemental copper. This is unsurprising as in a molten solution we only have positive copper ions and no hydrogen ions supplied by the water molecules as with an aqueous solution. In this case, the fact that we are discussing a solution of copper chloride as opposed to the molten salt means very little for our answer.

The important cation for both the solution and the molten salt is copper two plus, a metal that is less reactive than hydrogen. This cation will migrate to the negatively charged cathode and deposit in the form of elemental copper metal. The product in both cases will be elemental copper.

If we look at our available answer choices, only answer choice (C) mentions copper metal. Copper metal is the correct answer.

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