DP Chemistry Questionbank

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

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.

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.

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.

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.

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.

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

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).

Identify the missing component of the cell and its function.

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

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

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

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

Identify the missing component of the cell and its function.

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

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

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.

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).

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

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.

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)

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

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

Which reaction takes place at each electrode?

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.

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.