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Topic 11: Redox and electrochemistry

15. Redox equation: Describing changes in redox reactions

1. In the reaction, Mg + O2 -------- MgO
The O2 is the

1) Oxidizing agent, and is reduced 3) Reducing agent, and is reduced
2) Oxidizing agent, and is oxidized 4) Reducing agent, and is oxidized

2. In the reaction,
Mg + ZnCl2 ------ MgCl2 + Zn
Which is true of the magnesium ?
1) It is oxidized by losing electrons 3) It is reduced by losing electrons
2) It is oxidized by gaining electrons 4) It is reduced by gaining electrons
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3. Given the reaction: + 2+
Pb + 2 Ag -------- Pb + 2Ag
The lead atom is
1) Reduced, and its oxidation number changes from +o to +2
2) Reduced, and its oxidation number changes from +2 to 0
3) Oxidized, and its oxidation number changes from 0 to +2

4) Oxidized, and its oxidation number changes from +1 to 0

4. In the redox reaction: 4HCl + MnO2 --------- MnCl2 + 2H2O + Cl2

The manganese is
1) Oxidized, and its oxidation number changes from +2 to +4
2) Oxidized, and its oxidation number changes from +4 to +2
3) Reduced, and its oxidation number changes from +2 to +4
4) Reduced, and its oxidation number changes from +4 to +2

5. Given the reaction: 2I (aq) + Br2(l) --------- 2Br (aq) + I2(s)
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As the reaction takes place
1) The I ion is oxidized, and its oxidation number decreases
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2) The I ion is reduced, and its oxidation number decreases
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3) The I ion is oxidized, and its oxidation number increases
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4) The I ion is reduced, and its oxidation number increases

6. Given the reaction:
Zn(s) + 2HCl(aq) ------- ZnCl2(aq) + H2(g)
Which is true of hydrogen in this reaction?
1) Hydrogen is reduced, and its oxidation number increases
2) Hydrogen is reduced, and its oxidation number decreases
3) Hydrogen is oxidized, and its oxidation number increases
4) Hydrogen is oxidized , and its oxidation number decreases

7. Given the oxidation-reduction reaction:
Co(s) + PbCl2(aq) ------ CoCl2(aq) + Pb(s)
Which statement correctly describes the oxidation and reduction that occur?
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1) Co(s) is oxidized and Cl (aq) is reduced
2+
2) Co(s) is oxidized and Pb (aq) is reduced
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3) Co(s) is reduced and Cl (aq) is oxidized
4) Co(s) is reduced and Pb aq) is oxidized
2+(

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