DP Chemistry Questionbank

Which experimental methods could be used to observe the progress of the following reaction?

Cr₂O₇^2-(aq) + 6I^-(aq) + 14H⁺(aq) → 2Cr³⁺(aq) + 3I₂(aq) + 7H₂O(l) 

I. Change in colour 
II. Change in mass 
III. Change in electrical conductivity 

A.  I and II only 

B.  I and III only 

C.  II and III only 

D.  I, II and III

Which is a correct statement for the reaction below? 

2MnO₄^-(aq) + 6H⁺(aq) + 5NO₂^-(aq) → 2Mn²⁺(aq) + 5NO₃^-(aq) + 3H₂O(l) 

A. MnO₄^- is the reducing agent and the oxidation number of Mn increases.
B. MnO₄^- is the oxidizing agent and the oxidation number of Mn decreases. 
C. NO₂^- is the reducing agent and the oxidation number of N decreases. 
D. NO₂^- is the oxidizing agent and the oxidation number of N increases.

Magnesium chloride can be electrolysed.

Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922 K and 987 K respectively.

Anode (positive electrode):

Cathode (negative electrode):

Magnesium chloride can be electrolysed.

(i) Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922K and 987K respectively.

(ii) Identify the type of reaction occurring at the cathode (negative electrode).

(iii) State the products when a very dilute aqueous solution of magnesium chloride is electrolysed.

What is the order of decreasing reactivity of the metals (most reactive first)?

Zn(s) + Sn²⁺(aq) → Zn²⁺(aq) + Sn(s)
Cu(s) + Zn²⁺(aq) → No Reaction
Sn(s) + Cu²⁺(aq) → Sn²⁺(aq) + Cu(s)
Ag(s) + Cu²⁺(aq) → No Reaction

A.     Zn > Cu > Sn > Ag

B.     Sn > Zn > Ag > Cu

C.     Ag > Cu > Zn > Sn

D.     Zn > Sn > Cu > Ag

What is the oxidation half-equation in the redox reaction?

2S₂O₃^2–(aq) + I₂(aq) → S₄O₆^2–(aq) + 2I^–(aq)

A.     I₂(aq) + 2e^– → 2I^–(aq)

B.     2I^–(aq) → I₂(aq) + 2e^–

C.     2S₂O₃^2–(aq) → S₄O₆^2–(aq) + 2e^–

D.     S₄O₆^2–(aq) + 2e^– → 2S₂O₃^2–(aq)

A reaction takes place when a rechargeable battery is used:

Pb(s) + PbO₂(s) + 4H⁺(aq) + 2SO₄²⁻(aq) → 2PbSO₄(s) + 2H₂O(l)

Which statements are correct?

I.     H⁺ is reduced
II.     The oxidation state of Pb metal changes from 0 to +2
III.     PbO₂ is the oxidising agent

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

Suggest how the change of iodine concentration could be followed.

Determine the oxidation state of vanadium in each of the following species.

Formulate an equation for the reaction between VO²⁺(aq) and V²⁺(aq) in acidic solution to form V³⁺(aq).

Identify, from the table, a non-vanadium species that can reduce VO²⁺(aq) to V³⁺(aq) but no further.

Identify, from the table, a non-vanadium species that could convert ${\text{VO}}_2^{+}\text{(aq)}$ to V²⁺(aq).

Formulate an equation for the reaction between VO²⁺(aq) and V²⁺(aq) in acidic solution to form V³⁺(aq).

Formulate an equation for the oxidation of nickel(II) sulfide to nickel(II) oxide.

The nickel obtained from another ore, nickeliferous limonite, is contaminated with iron. Both nickel and iron react with carbon monoxide gas to form gaseous complexes, tetracarbonylnickel, $\text{Ni(CO}{\text{)}}_{\text{4}}\text{(g)}$, and pentacarbonyliron, $\text{Fe(CO}{\text{)}}_{\text{5}}\text{(g)}$. Suggest why the nickel can be separated from the iron successfully using carbon monoxide.

Suggest why experiments involving tetracarbonylnickel are very hazardous.

Which of the following does not react with dilute HCl(aq)?

A.     Na₂CO₃

B.     Cu

C.     Zn

D.     CuO

Which element is reduced in the following decomposition?

(NH₄)₂Cr₂O₇(s) → N₂(g) + Cr₂O₃(s) + 4H₂O(g)

A.     N

B.     H

C.     Cr

D.     O

Which of the following is not a redox reaction?

A.     CH₄(g) + Cl₂(g) → CH₃Cl(g) + HCl(g)

B.     C(s) + O₂(g) → CO₂(g)

C.     2CO(g) → CO₂(g) + C(s)

D.     CH₃COOH(aq) + NaOH(aq) →  CH₃COONa(aq) + H₂O(l)

Which element is reduced in the following decomposition?

(NH₄)₂Cr₂O₇(s) → N₂(g) + Cr₂O₃(s) + 4H₂O(g)

A.     N

B.     H

C.     Cr

D.     O

State the oxidation half-equation.

Deduce the overall redox equation for the reaction between acidic Sn²⁺(aq) and Cr₂O₇^2–(aq), using section 24 of the data booklet.

Determine the oxidation state of nitrogen in the two reactants.

Deduce, giving a reason, which species is the reducing agent.

Nickel is also used as a catalyst. It is processed from an ore until nickel(II) chloride solution is obtained. Identify one metal, using sections 24 and 25 of the data booklet, which will not react with water and can be used to extract nickel from the solution.

Deduce the redox equation for the reaction of nickel(II) chloride solution with the metal identified in (b)(i).

What are the oxidation states of chromium in (NH₄)₂Cr₂O₇ (s) and Cr₂O₃ (s)?

Which of the following is a redox reaction?

A. 3Mg (s) + 2AlCl₃ (aq) → 2Al (s) + 3MgCl₂ (aq)

B. SiO₂ (s) + 2NaOH (aq) → Na₂SiO₃ (aq) + H₂O (l)

C. KCl (aq) + AgNO₃ (aq) → AgCl (s) + KNO₃ (aq)

D. 2NaHCO₃ (aq) → Na₂CO₃ (aq) + CO₂ (g) + H₂O (l)

Consider the following half-equations:

I₂ (s) + 2e^– $\rightleftharpoons$ 2I^– (aq)                 E^θ = +0.54 V
(brown)          (colourless)

MnO₄^– (aq) + 8H⁺ (aq) + 5e^– $\rightleftharpoons$ Mn²⁺ (aq) + 4H₂O (l)                 E^θ = +1.51 V
(purple)                                      (colourless)                                                         

Which statement is correct for the reaction between KMnO₄ (aq) and KI (aq) in acidic conditions?

A. MnO₄^– reduces I^– to I₂.

B. I^– reduces MnO₄^– to Mn²⁺.

C. The colour changes from brown to purple.

D. MnO₄^– is oxidized to Mn²⁺.

Identify the best reducing agent in the table above.

In acidic solution, bromate ions, BrO₃⁻(aq), oxidize iodide ions, I⁻(aq).

BrO₃⁻(aq) + 6H⁺(aq) + 6e⁻ $\rightleftharpoons$ Br⁻(aq) + 3H₂O(l)

2I⁻(aq) $\rightleftharpoons$ I₂(s) + 2e⁻

Formulate the equation for the redox reaction.

Which equation shows oxygen undergoing reduction?

A.     2F₂ + O₂ → 2F₂O

B.     Na₂O + H₂O → 2NaOH

C.     H₂O₂ + 2HI → 2H₂O + I₂

D.     2CrO₄²⁻ + 2H⁺ $\rightleftharpoons$ Cr₂O₇²⁻ + H₂O

Which coefficients correctly balance this redox equation?

aFe²⁺(aq) + MnO₄⁻(aq) + bH⁺(aq) → cFe³⁺(aq) + Mn²⁺(aq) + dH₂O(l)

Which is correct for the reaction?

P₄ (s) + 3H₂O (l) + 3OH⁻ (aq) → PH₃ (g) + 3H₂PO₂⁻ (aq)

Bromate(V) ions act as oxidizing agents in acidic conditions to form bromide ions.

Deduce the half-equation for this reduction reaction.

Bromate(V) ions oxidize iron(II) ions, Fe²⁺, to iron(III) ions, Fe³⁺.

Deduce the equation for this redox reaction.

Bromate(V) ions act as oxidizing agents in acidic conditions to form bromide ions.

Deduce the half-equation for this reduction reaction.

Bromate(V) ions oxidize iron(II) ions, Fe²⁺, to iron(III) ions, Fe³⁺.

Deduce the equation for this redox reaction.

The combustion reaction in (f)(ii) can also be classed as redox. Identify the atom that is oxidized and the atom that is reduced.

State the oxidation number of carbon in sodium carbonate, Na₂CO₃.

MnO₂ is another possible catalyst for the reaction. State the IUPAC name for MnO₂.

Deduce the average oxidation state of carbon in product B.

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

State the name of this compound, applying IUPAC rules.

Deduce the coefficients required to complete the half-equation.

ReO₄⁻ (aq) + ____H⁺ (aq) + ____e⁻ ⇌ [Re(OH)₂]²⁺ (aq) + ____H₂O (l)        E^θ = +0.36 V

Compare the ease of oxidation of s-block and d-block metals to their melting points and densities. Use section 25 of the data booklet.

State the oxidation number of carbon in sodium carbonate, Na₂CO₃.

MnO₂ is another possible catalyst for the reaction. State the IUPAC name for MnO₂.

Deduce the average oxidation state of carbon in product B.

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

State the name of this compound, applying IUPAC rules.

Compare the ease of oxidation of s-block and d-block metals to their melting points and densities. Use section 25 of the data booklet.

Which is the species oxidized and the oxidizing agent in the reaction?

MnO₂ (s) + 4HCl (aq) → MnCl₂ (aq) + Cl₂ (g) + 2H₂O (l)

Discuss why different methods of reduction are needed to extract metals.

The following occurs when metal X is added to Y sulfate solution and Z sulfate solution. (X, Y and Z represent metal elements but not their symbols.)

X (s) + YSO₄ (aq) → XSO₄ (aq) + Y (s)
X (s) + ZSO₄ (aq): no reaction

What is the order of increasing reactivity?

A.  X < Y < Z

B.  Y < X < Z

C.  Z < Y < X

D.  Z < X < Y

State the oxidation state of manganese in ${\mathrm{MnO}}_2$ and ${\mathrm{MnCl}}_2$.

Deduce, referring to oxidation states, whether ${\mathrm{MnO}}_2$ is an oxidizing or reducing agent.

Suggest a metal that could replace nickel in a new half-cell and reverse the electron flow. Use section 25 of the data booklet.

State the oxidation state of manganese in ${\mathrm{MnO}}_2$ and ${\mathrm{MnCl}}_2$.

Deduce, referring to oxidation states, whether ${\mathrm{MnO}}_2$ is an oxidizing or reducing agent.

Suggest a metal that could replace nickel in a new half-cell and reverse the electron flow. Use section 25 of the data booklet.

What is correct for this redox reaction?

MnO₂(s) + 2$\text{I}$⁻ (aq) + 4H⁺(aq) → Mn²⁺(aq) + $\text{I}$₂(aq) + 2H₂O (l)

Write the half-equation for the reduction of hydrogen peroxide to water in acidic solution.

Deduce a balanced equation for the oxidation of Fe2+ by acidified hydrogen peroxide.

What is the change in the oxidation state of oxygen?

2Fe²⁺(aq) + H₂O₂(aq) + 2H⁺(aq) → 2H₂O (l) + 2Fe³⁺(aq)

A.  +1

B.  0

C.  −1

D.  −2

The three steps of the Winkler Method are redox reactions.

Deduce the reduction half-equation for step II.

The three steps of the Winkler Method are redox reactions.

Deduce the reduction half-equation for step II.

How many electrons are needed when the following half-equation is balanced using the lowest possible whole numbers?

__ NO₃^– (aq) + __ H⁺(aq) + __ e^– → __ NO (g) + __ H₂O (l)

A.  1

B.  2

C.  3

D.  5

What is the name of the compound with formula Ti₃(PO₄)₂?

A. Titanium phosphate

B. Titanium(II) phosphate

C. Titanium(III) phosphate

D. Titanium(IV) phosphate

Which combination best describes what is happening to chloromethane, CH₃Cl, in the equation below?

CH₃Cl (g) + H₂(g) $\rightleftharpoons$ CH₄(g) + HCl (g)

A.  Oxidation and addition

B.  Oxidation and substitution

C.  Reduction and addition

D.  Reduction and substitution

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Suggest an experiment that shows that magnesium is more reactive than zinc, giving the observation that would confirm this.

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Suggest an experiment that shows that magnesium is more reactive than zinc, giving the observation that would confirm this.

Deduce the half-equations for the reaction at each electrode.

Deduce the overall cell reaction including state symbols. Use section 7 of the data booklet.

Molten zinc chloride undergoes electrolysis in an electrolytic cell at 450 °C.

Deduce the half-equations for the reaction at each electrode.

Deduce the overall cell reaction including state symbols. Use section 7 of the data booklet.

Calculate the oxidation state of sulfur in iron(II) disulfide, FeS₂.

A voltaic cell is constructed from zinc and copper half-cells. Zinc is more reactive than copper. Which statement is correct when this cell produces electricity?

A. Electrons flow from the copper half-cell to the zinc half-cell. 

B. The concentration of Cu²⁺ (aq) increases. 

C. Electrons flow through the salt bridge. 

D. Negative ions flow through the salt bridge from the copper half-cell to the zinc half-cell.

Magnesium chloride can be electrolysed.

Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922 K and 987 K respectively.

Anode (positive electrode):

Cathode (negative electrode):

Magnesium chloride can be electrolysed.

(i) Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922K and 987K respectively.

(ii) Identify the type of reaction occurring at the cathode (negative electrode).

(iii) State the products when a very dilute aqueous solution of magnesium chloride is electrolysed.

Which statements are correct for a voltaic cell?

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

What occurs at the anode (positive electrode) during the electrolysis of molten strontium bromide?

A.     Formation of bromine and oxidation

B.     Formation of bromine and reduction

C.     Formation of strontium and oxidation

D.     Formation of strontium and reduction

What is the reaction type and major product at the anode (positive electrode) when molten sodium chloride is electrolysed using platinum electrodes?

A voltaic cell is made up of a Mn²⁺/Mn half-cell and a Ni²⁺/Ni half-cell.

Deduce the equation for the cell reaction.

The voltaic cell stated in part (ii) is partially shown below.

Draw and label the connections needed to show the direction of electron movement and ion flow between the two half-cells.

Deduce a balanced equation for the overall reaction when the standard nickel and iodine half-cells are connected.

Predict, giving a reason, the direction of movement of electrons when the standard nickel and manganese half-cells are connected.

Sketch a graph that would support the student’s hypothesis.

Identify the missing component of the cell and its function.

Deduce the half-equations for the reaction at each electrode when current flows.

Annotate the diagram with the location and direction of electron movement when current flows.

Deduce any change in the colour of the electrolyte during electrolysis.

Identify the missing component of the cell and its function.

Deduce the half-equations for the reaction at each electrode when current flows.

Annotate the diagram with the location and direction of electron movement when current flows.

Impure copper can be purified by electrolysis. In the electrolytic cell, impure copper is the anode (positive electrode), pure copper is the cathode (negative electrode) and the electrolyte is copper(II) sulfate solution.

Formulate the half-equation at each electrode.

Outline where and in which direction the electrons flow during electrolysis.

Which describes the flow of electrons in a voltaic cell?

A.   From the cathode (positive electrode) to the anode (negative electrode) through the external circuit

B.   From the anode (negative electrode) to the cathode (positive electrode) through the external circuit

C.   From the oxidizing agent to the reducing agent through the salt bridge

D.   From the reducing agent to the oxidizing agent through the salt bridge

An iron nail and a copper nail are inserted into a lemon.

Explain why a potential is detected when the nails are connected through a voltmeter.

Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?

A. Na (l)

B. Cl (g)

C. Cl₂ (g)

D. Na (s)

The following reaction occurs in a voltaic (galvanic) cell.

Mg (s) + 2Ag⁺ (aq) → Mg²⁺ (aq) + 2Ag (s)

Which reaction takes place at each electrode?

An iron nail and a copper nail are inserted into a lemon.

Explain why a potential is detected when the nails are connected through a voltmeter.

Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?

A. Na (l)

B. Cl (g)

C. Cl₂ (g)

D. Na (s)

Consider the following electrochemical cell.

What happens to the ions in the salt bridge when a current flows?

A. Na⁺ ions flow to the zinc half-cell and SO₄²⁻ ions flow to the copper half-cell.

B. Na⁺ ions flow to the copper half-cell and SO₄²⁻ ions flow to the zinc half-cell.

C. Na⁺ and SO₄²⁻ ions flow to the copper half-cell.

D. Na⁺ and SO₄²⁻ ions flow to the zinc half-cell.

The following reaction occurs in a voltaic (galvanic) cell.

Mg (s) + 2Ag⁺ (aq) → Mg²⁺ (aq) + 2Ag (s)

Which reaction takes place at each electrode?

Write the half-equation for the formation of gas bubbles at electrode 1.

Write the half-equation for the formation of gas bubbles at electrode 1.

The diagram shows an unlabelled voltaic cell for the reaction

${\mathrm{Pb}}^{2+} \left(\mathrm{aq}\right)+\mathrm{Ni} \left(\mathrm{s}\right)\to {\mathrm{Ni}}^{2+} \left(\mathrm{aq}\right)+\mathrm{Pb} \left(\mathrm{s}\right)$

Label the diagram with the species in the equation.

Suggest a metal that could replace nickel in a new half-cell and reverse the electron flow. Use section 25 of the data booklet.

The diagram shows an unlabelled voltaic cell for the reaction

${\mathrm{Pb}}^{2+}\left(\mathrm{aq}\right)+\mathrm{Ni}\left(\mathrm{s}\right)\to {\mathrm{Ni}}^{2+}\left(\mathrm{aq}\right)+\mathrm{Pb}\left(\mathrm{s}\right)$

Label the diagram with the species in the equation.

Suggest a metal that could replace nickel in a new half-cell and reverse the electron flow. Use section 25 of the data booklet.

Pure magnesium needed for making alloys can be obtained by electrolysis of molten magnesium chloride.

© International Baccalaureate Organization 2020.

Write the half-equations for the reactions occurring in this electrolysis.

Which statements are correct for electrolysis?

I.   An exothermic reaction occurs.
II.  Oxidation occurs at the anode (positive electrode).
III. The reaction is non-spontaneous.

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

What are the products of the electrolysis of molten potassium chloride, $\text{KCl\hspace{0.05em}(l)}$?

A student decides to build a voltaic cell consisting of an aluminium electrode, Al (s), a tin electrode, Sn (s), and solutions of aluminium nitrate, Al(NO₃)₃(aq) and tin(II) nitrate, Sn(NO₃)₂(aq).

Electron flow is represented on the diagram.

Label each line in the diagram using section 25 of the data booklet.

Write the equation for the expected overall chemical reaction in (a).

A student decides to build a voltaic cell consisting of an aluminium electrode, Al (s), a tin electrode, Sn (s), and solutions of aluminium nitrate, Al(NO₃)₃(aq) and tin(II) nitrate, Sn(NO₃)₂(aq).

Electron flow is represented on the diagram.

Label each line in the diagram using section 25 of the data booklet.

Write the equation for the expected overall chemical reaction in (a).

Which statement is correct about the electrolysis of molten lead(II) bromide, PbBr₂?

A.  Br⁻ ions accept electrons at the cathode (negative electrode).

B.  Pb²⁺ ions accept electrons at the anode (positive electrode).

C.  Br⁻ ions lose electrons at the anode (positive electrode).

D.  Pb²⁺ ions lose electrons at the cathode (negative electrode).

Deduce the half-equations for the reaction at each electrode.

Deduce the overall cell reaction including state symbols. Use section 7 of the data booklet.

Molten zinc chloride undergoes electrolysis in an electrolytic cell at 450 °C.

Deduce the half-equations for the reaction at each electrode.

Deduce the overall cell reaction including state symbols. Use section 7 of the data booklet.