How is the standard electrode potential of an electrode system determined?
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By measuring the difference in electrode potential between two half-cells.
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How is the standard electrode potential of an electrode system determined?
By measuring the difference in electrode potential between two half-cells.
What is the reduced substance in the reaction involving H2S and Cl2?
Chlorine, Cl2.
What is the oxidation number of fluorine?
Always -1.
What is the purpose of platinum(IV) oxide (PtO2) in the standard hydrogen electrode?
To increase the surface area of platinum to adsorb hydrogen gas, allowing closer contact with hydrogen ions in the solution.
What is the typical oxidation number of elements in Group 17 in a compound?
Normally -1.
What is the relationship between the reactivity of halogens and their ability to accept electrons?
The more reactive the halogen, the easier it is for the halogen to accept an electron.
What materials are used in the laboratory activity for investigating redox reactions?
Sulphuric acid, iron(II) sulphate, acidified potassium manganate(VII), and sodium hydroxide.
What happens during the reaction involving electropositive metals?
Electrons are transferred from the metal atom to the metal ion.
What characterizes metals at the top of the electrochemical series?
They are stronger reducing agents.
What is the oxidising agent in the reaction involving H2S and Cl2?
Chlorine, Cl2.
What is the standard electrode potential value for magnesium (Mg)?
E0 = -2.38 V.
What happens to the oxidation number of iron(II) ion, Fe²⁺ when it is converted to iron(III) ion, Fe³⁺?
The oxidation number increases from +2 to +3.
What characterizes metal ions at the bottom of the electrochemical series?
They are stronger oxidising agents.
What is the charge of Fe²⁺ and Fe³⁺?
Fe²⁺ has a charge of +2 and Fe³⁺ has a charge of +3.
What is the first step in setting up the experiment with carbon electrodes?
Connect the carbon electrodes to the galvanometer using connecting wires.
What occurs during an oxidation reaction?
A reactant loses electrons.
What solutions are used in the experiment with the carbon electrodes?
Iron(II) sulphate (FeSO4) and acidified potassium manganate(VII) (KMnO4).
What is the reduced substance in the reaction involving carbon dioxide?
Carbon dioxide, CO2.
What is the half equation for the oxidation of iron(II) ions?
Fe²⁺ (aq) → Fe³⁺ (aq) + e⁻
What are the standard conditions for measuring standard electrode potential?
1.0 mol dm−3 ion concentration, 1 atm gas pressure, 25 °C temperature, and using platinum as an inert electrode.
Which halogens are considered stronger oxidising agents?
Halogens located at the top of Group 17.
In the reaction between carbon and oxygen to produce carbon dioxide, what happens to the oxidation number of carbon?
The oxidation number of carbon increases.
What is the role of the zinc plate in the half-cell setup?
It acts as the electrode.
What role does oxygen play in a redox reaction involving magnesium?
Oxygen gains electrons and acts as an oxidising agent.
What can be determined based on the values of standard electrode potentials?
The oxidising agent and reducing agent.
What is the half equation for the oxidation of magnesium?
Mg → Mg²⁺ + 2e⁻.
What is the expected outcome of the laboratory activity?
To construct a table recording observations and inferences from the experiments.
What is the half equation for Chlorine water as an oxidising agent?
Cl₂ + 2e⁻ → 2Cl⁻
What does magnesium gain in the oxidation process?
Oxygen.
What concept do chemists use to explain redox reactions since the discovery of electrons?
The concept of electron transfer.
What is the aim of Laboratory Activity 1A?
To investigate oxidation and reduction reactions in terms of electron transfer at a distance.
How are oxidation and reduction defined in terms of oxidation numbers?
Oxidation occurs when the oxidation number increases; reduction occurs when the oxidation number decreases.
What is electrode potential?
The potential difference produced when an equilibrium is established between a metal and its ions in a half-cell.
What does the standard electrode potential, E0, measure?
The tendency of a substance to accept or donate electrons.
What is the overall ionic equation for the redox reaction in Laboratory Activity 1A?
5Fe²⁺ + MnO₄⁻ + 8H⁺ → 5Fe³⁺ + Mn²⁺ + 4H₂O
What is the reduction half equation for copper in a redox reaction?
Cu2+(aq) + 2e− → Cu(s).
What should be observed after dipping the electrodes into the solutions?
The direction of the deflection of the galvanometer needle.
What is the half equation for the reduction of oxygen?
O₂ + 4e⁻ → 2O²⁻.
How are the standard electrode potential values arranged in Table 1.7?
From the most negative to the most positive.
What happens when zinc, Zn is added to copper(II) nitrate, Cu(NO₃)₂ solution?
Zinc displaces copper, resulting in the formation of solid copper and a decrease in the blue color of the solution.
What is the aim of the laboratory activity described?
To investigate a redox reaction in the displacement of metal from its salt solution.
What does the deflection of the galvanometer needle indicate?
That there is a transfer of electrons from the reducing agent to the oxidising agent.
What does a more negative E0 value indicate about a substance?
It indicates a stronger reducing agent.
What is the reducing agent in the reaction?
Magnesium, Mg.
What is the oxidised substance in the reaction involving H2S and Cl2?
Hydrogen sulphide, H2S.
What is the limitation of the electron transfer concept in redox reactions?
It is limited to reactions associated with ionic compounds.
What color change occurs when iron(II) sulfate solution is oxidized?
The green color of iron(II) sulfate changes to brown.
Under what condition can chlorine, bromine, and iodine have a positive oxidation number?
When they are bound to a more electronegative element, such as oxygen.
What happens to magnesium in a redox reaction?
Magnesium loses electrons and acts as a reducing agent.
What is the standard electrode potential value for copper (Cu)?
E0 = +0.34 V.
What is the half equation for the oxidation of bromide ions?
2Br⁻ (aq) → Br₂ (aq) + 2e⁻.
How does the reactivity of halogens change down Group 17?
The reactivity of halogens decreases down Group 17.
What is the half equation for the reduction of chlorine molecules?
Cl₂ (aq) + 2e⁻ → 2Cl⁻ (aq).
How is Mg(NO3)2 named according to IUPAC nomenclature?
Magnesium nitrate.
How is magnesium oxide, MgO, formed?
When electrons are transferred from a metal to a non-metal.
What is the oxidation number of oxygen in magnesium oxide, MgO?
-2.
What does a more positive E0 value indicate about a substance?
It indicates a stronger oxidising agent.
Will the reaction occur between Mg(s) and Cu2+(aq)?
Yes, the reaction will occur because Mg is a stronger reducing agent than Cu2+.
What is the overall chemical equation for the reaction between potassium bromide and chlorine?
2KBr(aq) + Cl₂(aq) → Br₂(aq) + 2KCl(aq).
What type of reaction occurs when a reactant gains hydrogen?
Reduction reaction.
What is the relationship between the position of metals in the electrochemical series and their electropositivity?
More electropositive metals are located at higher positions in the electrochemical series.
What is the standard reference electrode used to measure standard electrode potential?
The standard hydrogen electrode.
What is the electron transfer process when iron(II) ion, Fe²⁺ is oxidised to iron(III) ion, Fe³⁺?
Iron(II) ion, Fe²⁺ releases an electron to produce iron(III) ion, Fe³⁺.
What is the reducing agent in the reaction involving H2S and Cl2?
Hydrogen sulphide, H2S.
What is the oxidation number of hydrogen in a compound?
Normally +1, except in metal hydrides where it is -1.
What is the oxidation half equation for zinc in a redox reaction?
Zn(s) → Zn2+(aq) + 2e−.
What is the oxidation number of oxygen in a compound?
Normally -2, except in peroxides where it is -1.
What occurs during a reduction reaction?
A reactant gains electrons.
How many electrons are involved in the reduction of MnO₄⁻?
5 electrons are involved.
What is the relationship between the E0 value of magnesium and its strength as a reducing agent?
The more negative E0 value of magnesium indicates it is a stronger reducing agent.
What is the oxidation number of bromine in bromate(V) ion, BrO3−?
+5.
What is an oxidising agent?
A substance that oxidises other substances and is reduced in a redox reaction.
What is the half equation for Potassium iodide as a reducing agent?
2I⁻ → I₂ + 2e⁻
How is the electrochemical series arranged?
According to the standard electrode potential, E0, from most negative to most positive.
What is the total charge balance for the oxidation of Fe²⁺?
Total charge = +2 on both sides.
What is the oxidation number of hydrogen in hydrogen chloride, HCl?
+1.
What does a more negative standard electrode potential value indicate about a substance?
It has a greater tendency to release electrons and is easier to undergo oxidation.
What is the IUPAC name for KMnO4?
Potassium manganate(VII).
What are the oxidised and reduced substances in the experiment?
Oxidised substance: Fe2+; Reduced substance: MnO4−.
What is the direction of electron flow in the experiment?
From the reducing agent (negative terminal) to the oxidising agent (positive terminal).
What are transition elements known for in terms of oxidation numbers?
They normally exhibit more than one oxidation number in their compounds.
What is the oxidation number for Group 1 elements in compounds?
+1.
Why does zinc become the negative terminal in the electrochemical cell?
Because zinc has a greater tendency to release electrons compared to hydrogen.
What does carbon dioxide lose in the reduction process?
Oxygen.
What does a more negative E0 value indicate about a metal?
It indicates that the metal is a stronger reducing agent.
What is the half equation for the reduction of manganate(VII) ions?
MnO₄⁻ (aq) + 8H⁺ (aq) + 5e⁻ → Mn²⁺ (aq) + 4H₂O (l)
Why is freshly prepared iron(II) sulphate, FeSO₄ solution used in the experiment?
It ensures the presence of Fe²⁺ ions for the redox reaction.
Why does copper (Cu) not undergo oxidation?
Because it is a weaker reducing agent than magnesium (Mg).
What reagent can verify the presence of iron(III) ion, Fe³⁺?
Potassium thiocyanate (KSCN) can be used.
What is the trend in the strength of halogens as oxidising agents?
Halogens become less effective as oxidising agents as you move down the group.
What color change occurs when potassium bromide solution is mixed with chlorine water?
The color changes from colorless to brown.
What does the Roman numeral (II) indicate for iron compounds?
The oxidation number of Fe is +2.
What is the overall reaction for the combustion of magnesium?
2Mg(s) + O2(g) → 2MgO(s).
What is the oxidation number of oxygen in hydrogen peroxide, H2O2?
-1.
What are the products of the reaction CuO(s) + H2(g) → Cu(s) + H2O(l)?
Copper (Cu) and water (H2O).
What role does sulphuric acid (H2SO4) play in the experiment?
It acts as an electrolyte separating the two solutions.
What is the half equation for Acidified hydrogen peroxide?
H₂O₂ + 2H⁺ + 2e⁻ → 2H₂O
What does the Roman numeral (III) indicate for chromium compounds?
The oxidation number of chromium is +3.
What is the half equation for Bromine water as an oxidising agent?
Br₂ + 2e⁻ → 2Br⁻
What is the E0 value of Cu2+ + 2e− ⇌ Cu?
+0.34 V.
What occurs in the displacement reaction between copper and silver nitrate?
Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s).
What is the sum of oxidation numbers in a compound?
It is zero.
What is the oxidising agent in the reaction?
Carbon dioxide, CO2.
What is an example of a reaction that does not involve oxygen?
The reaction between hydrogen sulfide, H2S, and chlorine, Cl2.
What is the principle behind the displacement of a halogen?
A more reactive halogen can displace a less reactive halogen from its halide solution.
What happens to halide ions as their position in Group 17 decreases?
They become stronger reducing agents and more easily release electrons.
In the same reaction, what happens to the oxidation number of oxygen?
The oxidation number of oxygen decreases.
What color change occurs when acidified potassium manganate(VII) solution is reduced?
The purple color of acidified potassium manganate(VII) changes to colorless.
How are half-cell equations written in the standard electrode potential series?
All half-cell equations are written as reduction.
What is the oxidation number of chlorine in potassium chlorate(I), KClO?
+1.
What is the reduced substance in the reaction between carbon and oxygen?
Oxygen (O2).
What is the half equation for Acidified potassium dichromate(VI)?
Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O
What does electropositivity refer to?
The tendency of atoms to release electrons to form cations.
What is the role of acidified potassium manganate(VII) in the reaction?
It acts as an oxidizing agent.
What is the negative terminal in a redox reaction?
The electrode where electrons are released.
What is the IUPAC name for Fe(NO3)3?
Iron(III) nitrate.
Will the reaction occur between Cu(s) and Zn2+(aq)?
No, the reaction will not occur because Cu is a weaker reducing agent than Zn2+.
What are the products of the reaction Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)?
Magnesium chloride (MgCl2) and hydrogen gas (H2).
What is the oxidation number of hydrogen in sodium hydride, NaH?
-1.
What is the significance of comparing E0 values of different substances?
It helps determine whether a substance acts as an oxidising agent or a reducing agent.
What is the oxidation number for a monoatomic ion?
It is equal to the charge of the ion.
What does a voltmeter reading of 0.76 V indicate in the context of the zinc electrode?
It shows the electrode potential of zinc, indicating that zinc has a greater tendency to release electrons compared to hydrogen.
What is the oxidation number of carbon in the carbonate ion (CO₃²−)?
+4.
What is the oxidised substance in the reaction involving magnesium?
Magnesium, Mg.
What role does bromine water, Br₂ play in the experiment?
Bromine water acts as an oxidising agent.
What happens when chlorine water is added to potassium bromide?
Chlorine displaces bromine from the potassium bromide solution.
What does IUPAC nomenclature indicate about metals with only one oxidation number?
They do not need Roman numerals in their naming.
What is produced when magnesium combusts in oxygen?
Magnesium oxide, MgO.
What is the role of iron(II) sulfate in the reaction?
It acts as a reducing agent.
Why is Ag+ considered a stronger oxidising agent than Ag?
Ag+ has a more positive E0 value, making it easier to receive electrons.
What is the significance of adding sodium hydroxide (NaOH) to the iron(II) sulphate solution?
To verify the product formed after the reaction.
What is a reducing agent?
A substance that reduces other substances and is oxidised in a redox reaction.
What materials are used in the laboratory activity?
Magnesium ribbon, lead plate, copper plate, and various nitrate solutions.
What must be the same in the half equations for a redox reaction?
The number of electrons in the equations must be the same.
How is the standard electrode potential series arranged?
In ascending order from the most negative to the most positive E0 values.
What is the overall ionic equation for the reaction that takes place?
Electrons move from iron(II) ion (Fe2+) to acidified manganate(VII) ion (MnO4−).
What happens to zinc, Zn during the displacement reaction?
Zinc is oxidised to form zinc ion, Zn²⁺, releasing two electrons.
What is the IUPAC name for K2Cr2O7?
Potassium dichromate(VI).
What is the half equation for Reactive metals like zinc?
Zn → Zn²⁺ + 2e⁻
What is the standard electrode potential, E0, of the hydrogen electrode?
0.00 V.
What is the standard electrode potential, E0, for the zinc half-cell?
E0 = -0.76 V.
What is the balanced chemical equation for the reaction between copper(II) oxide and carbon?
CuO + C → Cu + CO.
What type of reaction occurs when a reactant loses hydrogen?
Oxidation reaction.
What is the oxidised substance in the reaction between carbon and oxygen?
Carbon (C).
What is the half equation for Acidified potassium manganate(VII)?
MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O
What is the overall chemical equation for the reaction between zinc and copper(II) nitrate?
Zn(s) + Cu(NO3)2(aq) → Zn(NO3)2(aq) + Cu(s).
What is the purpose of leaving the apparatus set-up for 30 minutes?
To allow time for the reactions to occur and observe any color changes.
Why must the carbon electrode not touch the layer of sulphuric acid?
To prevent unwanted reactions and ensure accurate measurements.
What is the relationship between the E0 values of Cu and Mg regarding their reducing and oxidising strengths?
Cu has a more positive E0 value than Mg, making it a weaker reducing agent compared to Mg.
What happens to the color of chlorine water when it reacts?
It changes from greenish yellow to colorless.
What is the redox reaction involving ammonia and copper oxide?
2NH3(g) + 3CuO(s) → N2(g) + 3Cu(s) + 3H2O(l).
What is the total charge balance for the reduction of MnO₄⁻?
Total charge = +2 on both sides.
What is the observation when copper(II) ion, Cu²⁺ is reduced?
The blue color of the solution becomes paler and solid copper is deposited.
What is the E0 value of Ag+?
+0.80 V.
What is the E0 value of Mg2+?
-2.38 V.
Which is a stronger reducing agent: Cu or Ag?
Copper (Cu) is a stronger reducing agent compared to silver (Ag).
What is the half equation for the hydrogen half-cell?
2H+(aq) + 2e− ⇌ H2(g)
What does the E0 value of Ag indicate about its ability to act as an oxidising agent?
Silver ion (Ag+) is a stronger oxidising agent than copper(II) ions (Cu2+).
What does the oxidation number represent?
The charge of the elements in a compound based on electron transfer.
What can be concluded about the displacement reaction between copper (Cu) and magnesium ion (Mg2+)?
The displacement reaction does not occur because Cu is a weak reducing agent and Mg2+ is a weak oxidising agent.
What reagent can verify the presence of iron(II) ion, Fe²⁺?
Potassium permanganate (KMnO₄) can be used.
What happens to halide ions as you move down Group 17?
Halide ions become better reducing agents as you move down the group.
What does the color change in potassium bromide solution indicate?
Bromine, Br₂, is formed as bromide ions are oxidized.
What is the IUPAC name for Fe(NO3)2?
Iron(II) nitrate.
What is the half equation for Iron(II) sulphate as a reducing agent?
Fe²⁺ → Fe³⁺ + e⁻
What is the positive terminal in a redox reaction?
The electrode where electrons are accepted.
What is the oxidation number of manganese in MnO2?
+4.
What is the significance of the E0 value in determining whether a reaction will occur?
The E0 value indicates the strength of oxidising and reducing agents, helping to predict reaction feasibility.
How is the standard electrode potential value, E0, of zinc determined?
By using a half-cell with a zinc electrode in a solution of 1.0 mol dm−3 zinc ions, connected to a standard hydrogen electrode.
What is the standard hydrogen electrode composed of?
A platinum electrode dipped in an acid containing 1.0 mol dm−3 hydrogen ions and hydrogen gas at 1 atm pressure.
What is the E0 value of Ag+ + e− ⇌ Ag?
+0.80 V.
What is the half equation for the oxidation reaction at the zinc electrode?
Zn(s) → Zn2+(aq) + 2e−.
What is the oxidation number for elements in Group 13?
+3.
What should be included in the discussion of the laboratory activity?
Oxidation and reduction half equations, overall ionic equation, and identification of oxidised and reduced substances.
What observation indicates a displacement reaction when iodine is added to potassium bromide?
No color change occurs, indicating no displacement reaction takes place.
What does a more positive standard electrode potential value indicate about a substance?
It has a greater tendency to accept electrons and is easier to undergo reduction.
How can the standard electrode potential value, E0, be used?
To determine which substance will undergo oxidation or reduction and the strength of oxidising or reducing agents.
What is the oxidation number for all elements in their elemental form?
Zero.
What is the half equation for Sulphur dioxide as a reducing agent?
SO₂ + 2H₂O → SO₄²⁻ + 4H⁺ + 2e⁻
What is the oxidation number of sulfur in sulfur trioxide (SO₃)?
+6.
What is the oxidation number for elements in Group 2?
+2.
What is the function of a salt bridge in the standard electrode potential setup?
To maintain electrical neutrality by allowing the flow of ions between the two half-cells.
What is the significance of Roman numerals in IUPAC nomenclature?
They indicate the oxidation number of metals in their compounds.
What is the oxidation number of Copper(II) ion (Cu²+)?
+2.
What happens to silver ion (Ag+) during the reduction process?
It has a greater tendency to receive electrons to form silver atom (Ag).
