Electrochemistry
Chemistry - Electrochemistry
What process involves the loss of electrons in an electrochemical reaction?
Oxidation
Explanation: Oxidation is a chemical process characterized by the loss of electrons from an atom, ion, or molecule during a reaction, which increases its oxidation state.
What process involves the gain of electrons in an electrochemical cell?
Reduction
Explanation: Reduction is a chemical process characterized by the gain of electrons by an atom, ion, or molecule, which decreases its overall oxidation state.
At which specific electrode does oxidation strictly occur during a reaction?
Anode
Explanation: In any electrochemical cell, the anode is the designated electrode where oxidation strictly takes place, releasing electrons into the external circuit.
At which specific electrode does reduction strictly occur during a reaction?
Cathode
Explanation: The cathode is the electrode where reduction strictly occurs, as chemical species in the cell gain the electrons arriving from the external circuit.
What standard unit is used to measure electric potential difference?
Volt
Explanation: The volt is the standard derived unit used to measure electric potential difference, or electromotive force, between two points in a circuit.
What standard unit is used to measure the flow of electric current?
Ampere
Explanation: The ampere (often shortened to amp) is the standard base unit used to measure the rate of flow of electric current through a conductor.
What standard unit is used to measure total electrical charge?
Coulomb
Explanation: The coulomb is the standard unit of electric charge, defined as the total amount of charge transported by a constant current of one ampere in one second.
What type of cell generates electrical energy from spontaneous chemical reactions?
Galvanic
Explanation: A galvanic (or voltaic) cell derives its electrical energy from spontaneous, thermodynamically favorable redox reactions occurring within the cell.
What type of cell uses electrical energy to drive nonspontaneous reactions?
Electrolytic
Explanation: An electrolytic cell requires an external source of direct electrical energy to force an otherwise nonspontaneous chemical reaction to occur.
What specific component completes the circuit by allowing internal ion flow?
Bridge
Explanation: A salt bridge completes the electrical circuit by allowing the physical flow of ions between half-cells to maintain electrical neutrality.
What substance conducts electricity through the physical movement of dissolved ions?
Electrolyte
Explanation: An electrolyte is a substance that produces an electrically conducting solution when dissolved, allowing current to flow via the movement of its ions.
What type of battery cannot be easily recharged once its reagents are depleted?
Primary
Explanation: Primary batteries are single-use, non-rechargeable cells designed to be discarded once their internal chemical reactants are permanently depleted.
What type of battery is specifically designed to be electrically recharged?
Secondary
Explanation: Secondary batteries are rechargeable cells where the internal chemical reactions can be safely reversed by applying an external electrical current.
What is the common name for the destructive natural oxidation of metals?
Corrosion
Explanation: Corrosion is the natural, destructive oxidation of metals, gradually converting a refined metal into a more chemically stable oxide or salt.
Which metal is commonly used to galvanize iron and prevent it from rusting?
Zinc
Explanation: Zinc is commonly applied over iron or steel in a process called galvanization to act as a sacrificial layer, corroding first to prevent the iron from rusting.
What industrial process uses electric current to coat a metal object?
Electroplating
Explanation: Electroplating is an industrial process that uses electric current to reduce dissolved metal cations, forming a thin, protective or decorative metal coating on an object.
What specific chemical process describes the environmental rusting of elemental iron?
Oxidation
Explanation: The environmental rusting of iron is fundamentally an oxidation process where elemental iron loses electrons to oxygen in the presence of water.
What subatomic particle actually flows through the external wire of a circuit?
Electron
Explanation: Electrons are the negatively charged subatomic particles that actually travel through the external conductive wire connecting the electrodes of a circuit.
What specific type of ion migrates toward the cathode during electrolysis?
Cation
Explanation: Positively charged ions, known as cations, naturally migrate toward the negatively charged cathode during the process of electrolysis to gain electrons.
What specific type of ion migrates toward the anode during electrolysis?
Anion
Explanation: Negatively charged ions, called anions, migrate toward the positively charged anode to undergo oxidation and lose electrons during electrolysis.
What exact voltage value is assigned to the standard hydrogen electrode?
Zero
Explanation: By international convention, the standard hydrogen electrode (SHE) is assigned an exact reference potential value of zero volts at all temperatures.
Which state of matter is the electrolyte typically in a standard dry cell?
Paste
Explanation: In a standard dry cell battery, the electrolyte is formulated as a damp, immobile paste to prevent fluid leakage and allow practical, portable use.
What nonmetal material is widely used as an inexpensive inert electrode?
Graphite
Explanation: Graphite, a stable allotrope of carbon, is widely used as an inexpensive, electrically conductive, and chemically inert electrode material.
What expensive noble metal is frequently used for making durable inert electrodes?
Platinum
Explanation: Platinum is a highly expensive noble metal frequently chosen for inert electrodes due to its excellent conductivity and extreme resistance to chemical attack.
What diagnostic device is used to measure the voltage of an electrochemical cell?
Voltmeter
Explanation: A voltmeter is a diagnostic electrical instrument specifically connected in parallel to measure the electrical potential difference between two points.
What process forces a nonspontaneous chemical reaction using direct electrical current?
Electrolysis
Explanation: Electrolysis is the technique of using an external direct electric current to drive an otherwise nonspontaneous chemical reaction, such as splitting water.
What standard unit measures the resistance to electric current flow?
Ohm
Explanation: The ohm is the standard unit of electrical resistance, measuring the opposition a material presents to the continuous flow of electric current.
What is the generic term for an atom that has lost or gained electrons?
Ion
Explanation: An ion is the generic term for any atom or molecule that bears a net positive or negative electrical charge due to the loss or gain of electrons.
What specific cell type continuously consumes supplied external fuel and oxygen?
Fuel
Explanation: A fuel cell continuously generates electricity as long as it is continuously supplied with an external fuel source (like hydrogen) and an oxidant.
What describes a chemical substance that gets reduced to oxidize another species?
Oxidant
Explanation: An oxidant, or oxidizing agent, is a substance that gains electrons and gets reduced in order to force the oxidation of another chemical species.
What describes a chemical substance that gets oxidized to reduce another species?
Reductant
Explanation: A reductant, or reducing agent, is a substance that readily loses electrons and gets oxidized in order to reduce another chemical species in the reaction.
Whose equation directly relates cell potential to species concentration and temperature?
Nernst
Explanation: The Nernst equation allows chemists to determine the precise cell potential under non-standard conditions by relating it to species concentration and temperature.
Whose established laws quantitatively describe the mass altered during electrolysis?
Faraday
Explanation: Faraday's laws of electrolysis state that the mass of a substance altered at an electrode is directly proportional to the total electric charge passed through the cell.
What physical property describes the ability of a solution to carry current?
Conductivity
Explanation: Conductivity is the specific physical property that quantifies how well a given solution, material, or electrolyte can carry an electric current.
What thermodynamic state is reached when a battery is completely dead?
Equilibrium
Explanation: When a battery reaches chemical equilibrium, the forward and reverse reaction rates are equal, dropping the cell's net potential to zero (dead).
What specific thermodynamic quantity must be negative for a spontaneous cell reaction?
Gibbs
Explanation: The change in Gibbs free energy must have a negative value for a chemical reaction or electrochemical cell to be spontaneous and do useful electrical work.
What is the term for an electrode that strictly conducts without reacting?
Inert
Explanation: An inert electrode simply serves as a physical source or sink for electrons without chemically participating or degrading in the redox reaction itself.
What cell type has identical electrodes but utilizes different electrolyte molarities?
Concentration
Explanation: A concentration cell features chemically identical electrodes but generates a voltage purely due to a difference in the molarity of the two electrolyte solutions.
What extra voltage beyond the theoretical value is needed to drive electrolysis?
Overpotential
Explanation: Overpotential is the extra voltage required beyond the thermodynamically calculated theoretical value to drive an electrolytic reaction at a practical, observable rate.
Which highly reactive element is used in modern lightweight rechargeable batteries?
Lithium
Explanation: Lithium is the lightest solid metal and is highly reactive, making it ideal for providing high energy density in modern rechargeable batteries.
What heavy metal is traditionally used in automotive starting battery systems?
Lead
Explanation: Lead is a dense, heavy metal traditionally used in lead-acid automotive batteries due to its extreme reliability in providing high surge currents for starting engines.
What substance acts as the oxidizing agent in a standard hydrogen fuel cell?
Oxygen
Explanation: In a standard hydrogen fuel cell, oxygen gas acts as the oxidizing agent at the cathode, combining with incoming protons and electrons to form pure water.
What manufacturing process intentionally creates a protective oxide layer on aluminum?
Anodizing
Explanation: Anodizing is a controlled electrolytic process used to artificially increase the thickness of the natural protective oxide layer on the surface of metals like aluminum.
What type of electrode is explicitly consumed to protect another structural metal?
Sacrificial
Explanation: A sacrificial anode is made of a more easily oxidized metal (like zinc) that corrodes away intentionally to protect a primary metal structure (like steel) from corrosion.
What specific electrical parameter decreases significantly as a typical cell discharges?
Voltage
Explanation: As a typical battery discharges and its internal reactants are progressively consumed, its electrical potential or voltage gradually decreases toward zero.
Which reactive element acts as the active anode in a standard alkaline battery?
Zinc
Explanation: In a standard alkaline battery, powdered zinc acts as the active anode material, oxidizing and releasing electrons to power the external circuit.
What toxic halogen gas is produced at the anode during brine electrolysis?
Chlorine
Explanation: During the electrolysis of concentrated sodium chloride brine, chloride ions are oxidized at the anode to produce highly toxic, reactive chlorine gas.
What metal is commercially extracted exclusively via the molten Hall-Héroult process?
Aluminum
Explanation: The Hall-Héroult process is the major industrial electrolytic process utilized to extract pure aluminum metal from molten alumina.
What extremely strong acid is used as the liquid electrolyte in car batteries?
Sulfuric
Explanation: Sulfuric acid is the strong, highly corrosive liquid electrolyte used to facilitate ion exchange in traditional lead-acid automotive batteries.
What term describes the simultaneous oxidation and reduction of a single element?
Disproportionation
Explanation: Disproportionation is a specific type of redox reaction where a single element is simultaneously oxidized and reduced to form two distinct products.
What type of ionic compound is typically dissolved to make a conductive liquid?
Salt
Explanation: Soluble ionic compounds, commonly referred to generally as salts, are typically dissolved in water to separate into ions and create a conductive liquid electrolyte.
What pure gas is the primary product at the cathode during water electrolysis?
Hydrogen
Explanation: During the electrolysis of water, water molecules undergo reduction at the negatively charged cathode, producing pure hydrogen gas as the primary product.
What pure gas is the primary product at the anode during water electrolysis?
Oxygen
Explanation: During the electrolysis of water, water molecules undergo oxidation at the positively charged anode, producing pure oxygen gas as the primary product.
What term describes the directional movement of ions under an applied electric field?
Migration
Explanation: Migration refers to the physical, directed movement of charged ions through a solution or membrane under the direct influence of an applied electric field.
What phenomenon occurs when reaction products accumulate and temporarily hinder current flow?
Polarization
Explanation: Polarization occurs when the rapid accumulation of reaction products at an electrode alters the local potential and physically hinders the optimal flow of current.
Which specific electrode potential is arbitrarily set exactly to zero for reference?
Hydrogen
Explanation: The standard hydrogen electrode (SHE) potential is arbitrarily defined as exactly zero volts to serve as a universal baseline reference for all other elements.
What widely used reference electrode relies on liquid mercury and its solid chloride?
Calomel
Explanation: The saturated calomel electrode (SCE) is a robust, widely used secondary reference electrode based on elemental liquid mercury and solid mercury(I) chloride.
What protective condition occurs when a metal naturally forms a highly resistant oxide layer?
Passivation
Explanation: Passivation is the spontaneous formation of a hard, non-reactive microscopic surface film (usually an oxide) that strongly inhibits further corrosion of the underlying metal.
Which specialized electrode is predominantly utilized to accurately measure solution pH?
Glass
Explanation: The glass electrode is a specialized ion-selective electrode made of a doped glass membrane that is highly sensitive to hydrogen ions, used almost universally to measure pH.
What term describes the impure solid that naturally falls from the anode during copper refining?
Sludge
Explanation: Anode sludge is the collection of insoluble impurities, often containing valuable trace noble metals like gold and silver, that falls to the bottom during the electrolytic refining of copper.
