IB Chem Topic 9

Which are examples of reduction?

I. Fe³⁺ becomes Fe²⁺

II. Cl^– becomes Cl₂

III. CrO₃ becomes Cr^3+

• I and II only

• I and III only

• II and III only

• I, II and III

Which statement is correct for the electrolysis of a molten salt?

• Positive ions move toward the positive electrode.

• A gas is produced at the negative electrode.

• Only electrons move in the electrolyte.

• Both positive and negative ions move toward electrodes.

Which statement about the following reaction is correct?

2Br^–(aq) + Cl₂(aq) -> Br₂(aq) + 2Cl^–(aq)

• Br^–(aq) is reduced and gains electrons.

• Cl₂(aq) is reduced and loses electrons.

• Br^–(aq) is oxidized and loses electrons.

• Cl₂(aq) is oxidized and gains electrons.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

In which change does nitrogen undergo oxidation?

• NO₂ -> N₂O₄

• NO₃^– -> NO₂

• N₂O₅-> NO₃^–

• NH₃ -> N₂

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which statement is correct?

• Spontaneous redox reactions produce electricity in an electrolytic cell.

• Electricity is used to carry out a non-spontaneous redox reaction in a voltaic cell.

• Oxidation takes place at the negative electrode in a voltaic cell and the positive electrode in an electrolytic cell.

• Oxidation takes place at the negative electrode in a voltaic cell and reduction takes place at the positive electrode in an electrolytic cell.

The compound [Co(NH₃)₅Br]SO₄ is isomeric with the compound [Co(NH₃)₅SO₄]Br. What is the oxidation state of cobalt in these compounds?

• [Co(NH₃)₅Br]SO₄ : +3 [Co(NH₃)₅SO₄]Br: +3

• [Co(NH₃)₅Br]SO₄ : +1 [Co(NH₃)₅SO₄]Br: +2

• [Co(NH₃)₅Br]SO₄ : +2 [Co(NH₃)₅SO₄]Br: +3

• [Co(NH₃)₅Br]SO₄ : +3 [Co(NH₃)₅SO₄]Br: +2

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

What happens to vanadium during the reaction

VO²⁺(aq) ->VO₃^–(aq)?

• It undergoes oxidation and its oxidation number changes from +4 to +5.

• It undergoes oxidation and its oxidation number changes from +2 to +4.

• It undergoes reduction and its oxidation number changes from +2 to –1.

• It undergoes reduction and its oxidation number changes from +4 to +2.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which statement is correct about an oxidizing agent in a chemical reaction?

• It reacts with oxygen.

• It reacts with H+ ions.

• It loses electrons.

• It undergoes reduction.

What is the reducing agent in this reaction?

Cu(s) + 2NO₃^-(aq) + 4H⁺(aq) → Cu²⁺(aq) + 2NO₂(g) + 2H₂O(l)

• Cu(s)

• NO₃^-(aq)

• Cu²⁺(aq)

• H⁺(aq)

What process occurs at the cathode in a voltaic cell and at the anode in an electrolytic cell?

• Anode in voltaic cell: Reduction, Anode in electrolytic cell: Oxidation

• Anode in voltaic cell: Oxidation, Anode in electrolytic cell: Oxidation

• Anode in voltaic cell: Oxidation, Anode in electrolytic cell: Reduction

• Anode in voltaic cell: Reduction, Anode in electrolytic cell: Reduction