Basic Understanding Of Electrolysis Quiz

1. Bob wants to have a silver coated knife, he knows he can do it using electrolysis. He prepares Silver Nitrate solution as the electrolyte he is going to use. But firstly what should he put at the cathode and anode so that he gets his silver-plated knife?

Cathode : Knife ; Anode: Silver metal

Cathode: Silver metal ; Anode: Knife

It is fine both ways

In electrolysis, the cathode is the electrode where reduction occurs, meaning that the metal ions in the solution gain electrons and are deposited onto the cathode. In this case, Bob wants to deposit silver onto the knife, so the knife should be placed at the cathode. The anode, on the other hand, is where oxidation occurs, meaning that metal from the anode is oxidized and goes into the solution as metal ions. Since Bob wants to use silver metal as the source of silver ions, the silver metal should be placed at the anode. Therefore, the correct arrangement is Cathode: Knife; Anode: Silver metal.

Explanation

In electrolysis, the cathode is the electrode where reduction occurs, meaning that the metal ions in the solution gain electrons and are deposited onto the cathode. In this case, Bob wants to deposit silver onto the knife, so the knife should be placed at the cathode. The anode, on the other hand, is where oxidation occurs, meaning that metal from the anode is oxidized and goes into the solution as metal ions. Since Bob wants to use silver metal as the source of silver ions, the silver metal should be placed at the anode. Therefore, the correct arrangement is Cathode: Knife; Anode: Silver metal.

2. Which of the following is not an inert electrode?

Platinum

Mercury

Graphite

Mercury is not an inert electrode because it can participate in redox reactions. Inert electrodes do not undergo any chemical reactions during an electrochemical process and only serve as a conductor for the flow of electrons. Platinum and graphite are examples of inert electrodes commonly used in electrochemical cells, while mercury can be oxidized or reduced, making it an active electrode.

Explanation

Mercury is not an inert electrode because it can participate in redox reactions. Inert electrodes do not undergo any chemical reactions during an electrochemical process and only serve as a conductor for the flow of electrons. Platinum and graphite are examples of inert electrodes commonly used in electrochemical cells, while mercury can be oxidized or reduced, making it an active electrode.

3. Bob knows why he did not obtain his sodium metal when he electrolysed the sodium chloride solution he prepared. But he is now curious of how come Hydrogen ions can get discharged at the cathode. He came to the conclusion that it is beacause electrons from the current are transferred to the hydrogen ions to make them become hydrogen atoms.

True

False

The explanation for the given answer is that when Bob electrolysed the sodium chloride solution, the positively charged sodium ions migrated towards the cathode. However, instead of being discharged, the hydrogen ions present in the solution were discharged at the cathode. This is because the electrons from the current were transferred to the hydrogen ions, causing them to become hydrogen atoms. Therefore, the statement that hydrogen ions can get discharged at the cathode due to the transfer of electrons is true.

Explanation

The explanation for the given answer is that when Bob electrolysed the sodium chloride solution, the positively charged sodium ions migrated towards the cathode. However, instead of being discharged, the hydrogen ions present in the solution were discharged at the cathode. This is because the electrons from the current were transferred to the hydrogen ions, causing them to become hydrogen atoms. Therefore, the statement that hydrogen ions can get discharged at the cathode due to the transfer of electrons is true.

4. Bob is doing an electrolysis experiment and he wants to obtain sodium metal. He has a typical electrolysis set-up with Graphite electrodes. He has a bottle of Sodium Chloride crystals. What should he do with the Sodium Chloride crystals before he starts the experiment , so that he gets the result he wants?

Put the NaCl crystals into the crucible

Dissolve the NaCl crystals in water

Melt the NaCl crystals

In order to obtain sodium metal through electrolysis, Bob needs to have the sodium ions in a molten state. By melting the NaCl crystals, the sodium and chloride ions will separate, allowing the sodium ions to be attracted to the cathode and be reduced to sodium metal. Dissolving the NaCl crystals in water would not allow the ions to be separated and would not result in the formation of sodium metal. Putting the NaCl crystals into the crucible without melting them would also not allow for the separation of the ions and the formation of sodium metal.

Explanation

In order to obtain sodium metal through electrolysis, Bob needs to have the sodium ions in a molten state. By melting the NaCl crystals, the sodium and chloride ions will separate, allowing the sodium ions to be attracted to the cathode and be reduced to sodium metal. Dissolving the NaCl crystals in water would not allow the ions to be separated and would not result in the formation of sodium metal. Putting the NaCl crystals into the crucible without melting them would also not allow for the separation of the ions and the formation of sodium metal.

5. In the electrolysis of Dilute Sulfuric Acid, the gas produced at the cathode can rekindle a glowing splint.

True

False

In the electrolysis of Dilute Sulfuric Acid, the gas produced at the cathode is hydrogen gas (H2). Hydrogen gas is highly flammable and can burn with a pop sound when ignited. It does not rekindle a glowing splint, but rather extinguishes it. Therefore, the statement is false.

Explanation

In the electrolysis of Dilute Sulfuric Acid, the gas produced at the cathode is hydrogen gas (H2). Hydrogen gas is highly flammable and can burn with a pop sound when ignited. It does not rekindle a glowing splint, but rather extinguishes it. Therefore, the statement is false.

6. In the extraction of aluminium from bauxite, carbon anodes are used. Why must the carbon anodes be constantly changed after a certain period of time?

The carbon anodes reacted with the electrolyte

The carbon from the carbon anodes dissolve into the electrolyte and migrates to the cathode

The oxygen liberated at the anode reacts with the carbon anodes

The oxygen liberated at the anode reacts with the carbon anodes, causing them to gradually deteriorate and reduce in size. As the carbon anodes dissolve into the electrolyte, they migrate to the cathode, resulting in a loss of material from the anodes. Therefore, the carbon anodes need to be constantly changed after a certain period of time to maintain the efficiency of the extraction process.

Explanation

The oxygen liberated at the anode reacts with the carbon anodes, causing them to gradually deteriorate and reduce in size. As the carbon anodes dissolve into the electrolyte, they migrate to the cathode, resulting in a loss of material from the anodes. Therefore, the carbon anodes need to be constantly changed after a certain period of time to maintain the efficiency of the extraction process.

7. In the electrolysis of Copper(II) Sulfate solution, Copper(II) ions are preferentially discharged because of its lower position in the reactivity series as compared to Hydrogen ions.

True

False

In the electrolysis of Copper(II) Sulfate solution, Copper(II) ions are not preferentially discharged because of its lower position in the reactivity series as compared to Hydrogen ions. In fact, during electrolysis, the more reactive species is preferentially discharged at the cathode, while the less reactive species is discharged at the anode. Since Copper(II) ions are less reactive than Hydrogen ions, they will be discharged at the anode, while Hydrogen ions will be discharged at the cathode. Therefore, the given statement is false.

Explanation

In the electrolysis of Copper(II) Sulfate solution, Copper(II) ions are not preferentially discharged because of its lower position in the reactivity series as compared to Hydrogen ions. In fact, during electrolysis, the more reactive species is preferentially discharged at the cathode, while the less reactive species is discharged at the anode. Since Copper(II) ions are less reactive than Hydrogen ions, they will be discharged at the anode, while Hydrogen ions will be discharged at the cathode. Therefore, the given statement is false.