Electrochemistry Flashcards
What is the electrolyte?
The electrolyte is the ionic compound in molten or dissolved solution that conducts the electricity.
What is the anode?
The anode is the positive electrode.
What is the cathode?
The cathode is the negative electrode.
Which way do electrons flow in the circuit during electrolysis?
Electrons flow from the anode to the cathode.
Why are cations attracted to the cathode?
Positive cations are attracted to the negatively charged cathode because opposite charges attract.
Why are anions attracted to the anode?
Negative anions are attracted to the positively charged anode because opposite charges attract.
Define electrolysis
Electrolysis is the process of using an electric current to decompose or break down a molten or aqueous ionic compound.
What is produced at the cathode during electrolysis of molten lead(II) bromide?
Molten lead is produced at the cathode during electrolysis of molten lead(II) bromide.
What is produced at the anode during electrolysis of molten lead(II) bromide?
Brown fumes of bromine gas are produced at the anode during electrolysis of molten lead(II) bromide.
What would be the products of electrolysis of molten zinc chloride?
The products of electrolysis of molten zinc chloride would be zinc at the cathode and chlorine at the anode.
What type of electrodes are typically used in the electrolysis of molten compounds?
Graphite or platinum electrodes are typically used in the electrolysis of molten compounds.
Why do molten ionic compounds conduct electricity?
Molten ionic compounds conduct electricity because their ions can move freely and carry the current.
Explain how a molecule of chlorine forms during the electrolysis of lead(II) chloride.
Two chloride ions are attracted to the anode where they each lose one electron.
They bond to form a molecule of chlorine.
2Cl- ⟶ Cl2 + 2e-
What is brine?
Brine is a concentrated solution of aqueous sodium chloride.
What are the products of the electrolysis of brine?
The products of the electrolysis of brine are chlorine gas, hydrogen gas, and sodium hydroxide solution
What gas is produced at the anode during the electrolysis of brine?
Chlorine gas is produced at the anode during the electrolysis of brine.
In the electrolysis of dilute sulfuric acid, what gas is produced at the cathode?
In the electrolysis of dilute sulfuric acid, hydrogen gas is produced at the cathode.
What is produced at the anode during the electrolysis of dilute sulfuric acid?
Oxygen gas is produced at the anode during the electrolysis of dilute sulfuric acid.
What is the test and result for oxygen gas?
The test for oxygen gas is that a glowing splint will relight when dipped into a sample of the gas.
What is the test and result for hydrogen gas?
Hydrogen gas is tested for by dipping a lit splint into a sample of the gas, which will produce a squeaky pop.
What is the test and result for chlorine gas?
The test for chlorine gas is that damp litmus paper will turn red and then bleach to a white colour when dipped into a sample of the gas.
What ions are always present in aqueous solutions?
Aqueous solutions always have H+ and OH- ions present from the splitting of water molecules.
What determines which ions are discharged at the electrodes during electrolysis of aqueous solutions?
The relative reactivity of the elements involved determines which ions are discharged at the electrodes during electrolysis of aqueous solutions.
In the electrolysis of concentrated copper(II) chloride solution, what is produced at the anode?
In the electrolysis of concentrated copper(II) chloride solution, chlorine is produced at the anode.
What is produced at the anode during the electrolysis of dilute halide solutions?
Oxygen is produced at the anode during the electrolysis of dilute halide solutions.
What is produced at the cathode during the electrolysis of aqueous copper sulfate?
Copper metal is produced at the cathode during the electrolysis of aqueous copper sulfate.
In the electrolysis of aqueous copper sulfate with copper electrodes, what happens to the anode?
In the electrolysis of aqueous copper sulfate with copper electrodes, the anode decreases in mass.
What is produced at the anode during the electrolysis of dilute sulfuric acid?
Oxygen gas is produced at the anode during the electrolysis of dilute sulfuric acid.
What ions are attracted to the positive electrode?
Negatively charged OH- ions and non-metal ions are attracted to the positive electrode.
What ions are attracted to the negative electrode?
H+ ions and metal ions are attracted to the negative electrode.
How is the product at the cathode determined?
The product at the cathode is determined by the position of the metal in the reactivity series relative to hydrogen.
What is produced at the cathode during electrolysis of dilute sodium chloride solution?
Hydrogen gas is produced at the cathode during electrolysis of sodium chloride solution.
What is oxidation in terms of electron transfer?
Oxidation is the loss of electrons.
What is reduction in terms of electron transfer?
Reduction is the gain of electrons.
Write the ionic half-equation for the reduction of copper(II) ions
Cu2+ + 2e- → Cu
Write the ionic half-equation for the oxidation of chloride ions
2Cl- → Cl2 + 2e-
What is the ionic half-equation for the reduction of hydrogen ions?
2H+ + 2e- → H2
Write the ionic half- equation for the reduction of Sn2+ ions at the cathode?
Sn2+ + 2e- → Sn
State the ionic half- equation for the reduction of Pb2+ ions at the cathode.
Pb2+ + 2e- → Pb
What is electroplating?
Electroplating is process of coating the surface of one metal with a layer of a different metal.
Give one use of electroplating.
Uses of electroplating include:
Improving the appearance of objects (e.g. jewellery)
Coating objects to prevent corrosion / damage (e.g. cutlery)
An iron nail is being electroplated with copper.
Which metal is being used as the anode?
The anode is the copper rod as the anode is the metal you are using the coat the other metal with.
What is the ionic half- equation for the reaction at the anode which forms Sn2+ ions when electroplating with tin?
Sn → Sn2+ + 2e-
What is the ionic half- equation for the reaction at the cathode forming Sn atoms when electroplating with tin?
Sn2+ + 2e- → Sn
A substance is electroplated with tin (Sn)
What is the ionic half- equation for the formation of Sn2+ ions at the anode?
Sn → Sn2+ + 2e-
A substance is electroplated with tin.
What is the ionic half- equation for the formation of Sn atoms at the cathode?
Sn2+ + 2e- → Sn
What is a fuel cell?
A fuel cell is an electrochemical cell in which a fuel donates electrons at one electrode and oxygen gains electrons at the other electrode.
What are the products of a hydrogen-oxygen fuel cell?
A hydrogen-oxygen fuel cell produces water and energy.
Which direction do the electrons flow in a fuel cell?
The electrons flow from anode to cathode.
Where is air containing oxygen pumped into a fuel cell?
The air containing oxygen is pumped into the cathode compartment.
What is the symbol equation for the reaction between hydrogen and oxygen to form water?
2H2 + O2 → 2H2O
State two disadvantages of using fuel cells.
Two disadvantages could be from the following:
Materials used in producing fuel cells are expensive
Hydrogen is difficult to store as it is flammable
State two advantages of using fuel cells
Two advantages could be from the following:
The only product is water so less pollution
They produce more energy per kilogram than either petrol or diesel
