Can You Pass This Electrolysis Quiz?
In the scientific field of chemistry, the process of electrolysis involves using a direct electric current to garner an otherwise non-spontaneous chemical reaction. What else do you know about the process, how it works and what it’s used for? Answer the following questions and find out for sure!
- 1.
What is the charge of a cathode? What ions do it attract?
- A.
Negatively-charged ; cations
- B.
Negatively-charged ; anions
- C.
Positively-charged ; cations
- D.
Positively-charged ; anions
Correct Answer
A. Negatively-charged ; cationsExplanation
A cathode is negatively charged, which means it has an excess of electrons. Since opposite charges attract, the cathode will attract positively charged ions, also known as cations.Rate this question:
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- 2.
In the case of electrolysis with concentrated sulfuric acid as the electrolyte and with inert electrodes, which ions will be discharged at the electrodes?
- A.
Hydroxide ions and hydrogen ions
- B.
Hydroxide ions and sulfate ions
- C.
Hydrogen ions and sulfate ions
- D.
Sulfur ions and hydrogen ions
Correct Answer
C. Hydrogen ions and sulfate ionsExplanation
When electrolysis is carried out with concentrated sulfuric acid as the electrolyte and inert electrodes, hydrogen ions (H+) and sulfate ions (SO4^2-) will be discharged at the electrodes. This is because sulfuric acid dissociates into hydrogen ions and sulfate ions in solution. At the cathode (negative electrode), hydrogen ions will be reduced to form hydrogen gas (H2), while at the anode (positive electrode), sulfate ions will be oxidized to form oxygen gas (O2) and water (H2O).Rate this question:
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- 3.
Why must the electrolyte be molten or aqueous when undergoing electrolysis
- A.
So that electrostatic forces of attraction are overcome and the ions are mobile
- B.
So that covalent bonds are overcome and the ions are mobile
- C.
So that van de waals forces are overcome and the electrons are mobile
- D.
So that hydrogen bonds are overcome and electrons are mobile
Correct Answer
A. So that electrostatic forces of attraction are overcome and the ions are mobileExplanation
In order for electrolysis to occur, the electrolyte must be molten or aqueous. This is because in a molten or aqueous state, the electrostatic forces of attraction between the ions in the electrolyte are overcome, allowing the ions to become mobile. This mobility of ions is necessary for the flow of electric current during electrolysis.Rate this question:
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- 4.
In the electrolysis of molten lead (II) iodide, give the equation for the reaction at the cathode
Correct Answer
Pb²⁺ (l) + 2e⁻ → Pb (l)
Pb²⁺(l)+2e⁻→Pb(l)
Pb2+(l)+2e-→Pb(l)
Pb2+(l) + 2e- → Pb(l)
Pb2+(l)+2e- → Pb(l)Explanation
The correct answer is Pb²⁺ (l) + 2e⁻ → Pb (l). This equation represents the reduction reaction that occurs at the cathode during the electrolysis of molten lead (II) iodide. In this reaction, lead ions (Pb²⁺) gain two electrons (2e⁻) to form lead atoms (Pb). This reduction reaction is necessary to balance the oxidation reaction that occurs at the anode during the electrolysis process.Rate this question:
- 5.
Graphite can conduct electricity because although it has 4 free electrons, only 3 are used for bonding. Hence, there is 1 free electron for conducting electricity.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Graphite can conduct electricity because it has 4 free electrons, but only 3 are used for bonding. This means that there is 1 free electron available for conducting electricity.Rate this question:
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- 6.
In the electrolysis of molten NaOH using inert electrodes, what observations will there be at the electrodes?
- A.
Effervescence of green-yellow pungent gas
- B.
Deposits of a black solid
- C.
Effervescence of colourless ordourless gas
- D.
Deposits of yellow solid
- E.
Deposits of silvery-gray solid
Correct Answer(s)
C. Effervescence of colourless ordourless gas
E. Deposits of silvery-gray solidExplanation
During the electrolysis of molten NaOH using inert electrodes, the observation at the positive electrode (anode) will be the effervescence of a colorless, odorless gas. This gas is oxygen (O2) which is produced by the oxidation of water molecules at the anode. At the negative electrode (cathode), there will be deposits of a silvery-gray solid. This solid is sodium (Na) which is formed by the reduction of sodium ions (Na+) present in the molten NaOH.Rate this question:
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- 7.
Why isnt pure water a good eletrolyte?
- A.
Water molecules are held by metallic bonds and do not have mobile electrons or ions
- B.
Water molecules are held by ionic bonds and have no mobile electrons or ions
- C.
Water moleculs are held by covalent bonds and have no mobile electrons or ions
Correct Answer
C. Water moleculs are held by covalent bonds and have no mobile electrons or ionsExplanation
Pure water is not a good electrolyte because water molecules are held together by covalent bonds, which means they do not dissociate into ions. In order for a substance to be a good electrolyte, it needs to have mobile ions or electrons that can carry an electric current. Since pure water does not have these mobile ions or electrons, it cannot conduct electricity effectively.Rate this question:
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- 8.
In the purification of copper ore, should the impure copper be used as the cathode or anode
- A.
Anode, so that the impure copper will gain electrons to become copper ion and travel to the pure copper cathode
- B.
Anode, so that the impure copper will lose electrons to become copper ion and travel to the pure copper cathode
- C.
Cathode, so that the impure copper will lose electrons to become copper ion and travel to the pure copper cathode
- D.
Anode, so that the impure copper will gain electrons to become copper ion and travel to the pure copper cathode
Correct Answer
B. Anode, so that the impure copper will lose electrons to become copper ion and travel to the pure copper cathodeExplanation
In the purification of copper ore, the impure copper should be used as the anode. This is because during the electrolysis process, the anode is the electrode where oxidation occurs. By using the impure copper as the anode, it will lose electrons and be oxidized, forming copper ions. These copper ions will then travel to the pure copper cathode, where reduction occurs, allowing the impurities to be removed and leaving behind pure copper.Rate this question:
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- 9.
Why should a DC current be used in electrolysis?
- A.
The charges of the electrodes will be constant, hence the components will stay at the respective electrode
- B.
The electronegativity of the electrodes will be constant, hence the components will stay at the respective electrode
- C.
The temperature of the electrodes will be constant, hence the components will stay at the respective electrode
- D.
The rate of reaction of the electrodes will be constant, hence the components will stay at the respective electrode
Correct Answer
A. The charges of the electrodes will be constant, hence the components will stay at the respective electrodeExplanation
In electrolysis, a DC current should be used because it ensures that the charges of the electrodes remain constant. This is important because it allows the components involved in the electrolysis process to stay at their respective electrodes. If the charges were not constant, the components could migrate and mix, leading to an inaccurate or ineffective electrolysis process. Therefore, using a DC current helps to maintain the stability and integrity of the components during electrolysis.Rate this question:
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- 10.
When the voltage of the battery increases, the current increases, hence the rate of electrolysis decreases.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
When the voltage of the battery increases, the current also increases. According to Ohm's Law, the current is directly proportional to the voltage. Therefore, if the voltage increases, the current will also increase. Electrolysis is a process that requires the flow of electric current, so if the current increases, the rate of electrolysis will also increase, not decrease. Hence, the given statement is false.Rate this question:
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Current Version
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Aug 26, 2024Quiz Edited by
ProProfs Editorial Team -
May 08, 2011Quiz Created by
Lucasjiang
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